quart package

Module contents

quart.abort(status_or_response: Union[int, quart.wrappers.response.Response], description: Optional[str] = None, name: Optional[str] = None) → NoReturn

Raises a HTTPException with the status code or response given.

This can be used either with a status code (with optional description and name) or with a Response object. The latter allows for an abort (after response functions etc aren’t called) with a custom response.

abort(403)
abort(Response("Message"))
quart.after_this_request(func: Callable) → Callable

Schedule the func to be called after the current request.

This is useful in situations whereby you want an after request function for a specific route or circumstance only, for example,

def index():
    @after_this_request
    def set_cookie(response):
        response.set_cookie('special', 'value')
        return response

    ...
class quart.Blueprint(name: str, import_name: str, static_folder: Optional[str] = None, static_url_path: Optional[str] = None, template_folder: Optional[str] = None, url_prefix: Optional[str] = None, subdomain: Optional[str] = None, root_path: Optional[str] = None)

Bases: quart.static.PackageStatic

A blueprint is a collection of application properties.

The application properties include routes, error handlers, and before and after request functions. It is useful to produce modular code as it allows the properties to be defined in a blueprint thereby defering the addition of these properties to the app.

json_decoder

The decoder to use for routes in this blueprint, the default, None, indicates that the app encoder should be used.

json_encoder

The encoder to use for routes in this blueprint, the default, None, indicates that the app encoder should be used.

url_prefix

An additional prefix to every route rule in the blueprint.

add_app_template_filter(func: Callable, name: Optional[str] = None) → None

Add an application wide template filter.

This is designed to be used on the blueprint directly, and has the same arguments as add_template_filter(). An example usage,

def filter():
    ...

blueprint = Blueprint(__name__)
blueprint.add_app_template_filter(filter)
add_app_template_global(func: Callable, name: Optional[str] = None) → None

Add an application wide template global.

This is designed to be used on the blueprint directly, and has the same arguments as add_template_global(). An example usage,

def global():
    ...

blueprint = Blueprint(__name__)
blueprint.add_app_template_global(global)
add_app_template_test(func: Callable, name: Optional[str] = None) → None

Add an application wide template test.

This is designed to be used on the blueprint directly, and has the same arguments as add_template_test(). An example usage,

def test():
    ...

blueprint = Blueprint(__name__)
blueprint.add_app_template_test(test)
add_url_rule(path: str, endpoint: Optional[str] = None, view_func: Optional[Callable] = None, methods: Optional[Iterable[str]] = None, defaults: Optional[dict] = None, host: Optional[str] = None, subdomain: Optional[str] = None, *, provide_automatic_options: Optional[bool] = None, is_websocket: bool = False, strict_slashes: bool = True) → None

Add a route/url rule to the blueprint.

This is designed to be used on the blueprint directly, and has the same arguments as add_url_rule(). An example usage,

def route():
    ...

blueprint = Blueprint(__name__)
blueprint.add_url_rule('/', route)
add_websocket(path: str, endpoint: Optional[str] = None, view_func: Optional[Callable] = None, defaults: Optional[dict] = None, host: Optional[str] = None, subdomain: Optional[str] = None, *, strict_slashes: bool = True) → None

Add a websocket rule to the blueprint.

This is designed to be used on the blueprint directly, and has the same arguments as add_websocket(). An example usage,

def route():
    ...

blueprint = Blueprint(__name__)
blueprint.add_websocket('/', route)
after_app_request(func: Callable) → Callable

Add a after request function to the app.

This is designed to be used as a decorator, and has the same arguments as after_request(). It applies to all requests to the app this blueprint is registered on. An example usage,

blueprint = Blueprint(__name__)
@blueprint.after_app_request
def after():
    ...
after_app_websocket(func: Callable) → Callable

Add an after websocket function to the App.

This is designed to be used as a decorator, and has the same arguments as after_websocket(). It applies to all requests to the ppe this blueprint is registerd on. An example usage,

blueprint = Blueprint(__name__)
@blueprint.after_app_websocket
def after():
    ...
after_request(func: Callable) → Callable

Add an after request function to the Blueprint.

This is designed to be used as a decorator, and has the same arguments as after_request(). It applies only to requests that are routed to an endpoint in this blueprint. An example usage,

blueprint = Blueprint(__name__)
@blueprint.after_request
def after():
    ...
after_websocket(func: Callable) → Callable

Add an after websocket function to the Blueprint.

This is designed to be used as a decorator, and has the same arguments as after_websocket(). It applies only to requests that are routed to an endpoint in this blueprint. An example usage,

blueprint = Blueprint(__name__)
@blueprint.after_websocket
def after():
    ...
app_context_processor(func: Callable) → Callable

Add a context processor function to the app.

This is designed to be used as a decorator, and has the same arguments as context_processor(). This will add context to all templates rendered. An example usage,

blueprint = Blueprint(__name__)
@blueprint.app_context_processor
def processor():
    ...
app_errorhandler(error: Union[Type[Exception], int]) → Callable

Add an error handler function to the App.

This is designed to be used as a decorator, and has the same arguments as errorhandler(). It applies only to all errors. An example usage,

blueprint = Blueprint(__name__)
@blueprint.app_errorhandler(404)
def not_found():
    ...
app_template_filter(name: Optional[str] = None) → Callable

Add an application wide template filter.

This is designed to be used as a decorator, and has the same arguments as template_filter(). An example usage,

blueprint = Blueprint(__name__)
@blueprint.app_template_filter()
def filter(value):
    ...
app_template_global(name: Optional[str] = None) → Callable

Add an application wide template global.

This is designed to be used as a decorator, and has the same arguments as template_global(). An example usage,

blueprint = Blueprint(__name__)
@blueprint.app_template_global()
def global(value):
    ...
app_template_test(name: Optional[str] = None) → Callable

Add an application wide template test.

This is designed to be used as a decorator, and has the same arguments as template_test(). An example usage,

blueprint = Blueprint(__name__)
@blueprint.app_template_test()
def test(value):
    ...
app_url_defaults(func: Callable) → Callable

Add a url default preprocessor.

This is designed to be used as a decorator, and has the same arguments as url_defaults(). This will apply to all urls. An example usage,

blueprint = Blueprint(__name__)
@blueprint.app_url_defaults
def default(endpoint, values):
    ...
app_url_value_preprocessor(func: Callable) → Callable

Add a url value preprocessor.

This is designed to be used as a decorator, and has the same arguments as app_url_value_preprocessor(). This will apply to all URLs. An example usage,

blueprint = Blueprint(__name__)
@blueprint.app_url_value_preprocessor
def processor(endpoint, view_args):
    ...
before_app_first_request(func: Callable) → Callable

Add a before request first function to the app.

This is designed to be used as a decorator, and has the same arguments as before_first_request(). It is triggered before the first request to the app this blueprint is registered on. An example usage,

blueprint = Blueprint(__name__)
@blueprint.before_app_first_request
def before_first():
    ...
before_app_request(func: Callable) → Callable

Add a before request function to the app.

This is designed to be used as a decorator, and has the same arguments as before_request(). It applies to all requests to the app this blueprint is registered on. An example usage,

blueprint = Blueprint(__name__)
@blueprint.before_app_request
def before():
    ...
before_app_websocket(func: Callable) → Callable

Add a before request websocket to the App.

This is designed to be used as a decorator, and has the same arguments as before_websocket(). It applies to all requests to the app this blueprint is registered on. An example usage,

blueprint = Blueprint(__name__)
@blueprint.before_app_websocket
def before():
    ...
before_request(func: Callable) → Callable

Add a before request function to the Blueprint.

This is designed to be used as a decorator, and has the same arguments as before_request(). It applies only to requests that are routed to an endpoint in this blueprint. An example usage,

blueprint = Blueprint(__name__)
@blueprint.before_request
def before():
    ...
before_websocket(func: Callable) → Callable

Add a before request websocket to the Blueprint.

This is designed to be used as a decorator, and has the same arguments as before_websocket(). It applies only to requests that are routed to an endpoint in this blueprint. An example usage,

blueprint = Blueprint(__name__)
@blueprint.before_websocket
def before():
    ...
context_processor(func: Callable) → Callable

Add a context processor function to this blueprint.

This is designed to be used as a decorator, and has the same arguments as context_processor(). This will add context to all templates rendered in this blueprint’s routes. An example usage,

blueprint = Blueprint(__name__)
@blueprint.context_processor
def processor():
    ...
endpoint(endpoint: str) → Callable

Add an endpoint to the blueprint.

This is designed to be used as a decorator, and has the same arguments as endpoint(). An example usage,

blueprint = Blueprint(__name__)
@blueprint.endpoint('index')
def index():
    ...
errorhandler(error: Union[Type[Exception], int]) → Callable

Add an error handler function to the Blueprint.

This is designed to be used as a decorator, and has the same arguments as errorhandler(). It applies only to errors that originate in routes in this blueprint. An example usage,

blueprint = Blueprint(__name__)
@blueprint.errorhandler(404)
def not_found():
    ...
json_decoder: Optional[Type[JSONDecoder]] = None
json_encoder: Optional[Type[JSONEncoder]] = None
make_setup_state(app: Quart, first_registration: bool, *, url_prefix: Optional[str] = None) → BlueprintSetupState

Return a blueprint setup state instance.

Parameters

  • first_registration – True if this is the first registration of this blueprint on the app.

  • url_prefix – An optional prefix to all rules

record(func: Callable[[BlueprintSetupState], Callable]) → None

Used to register a deferred action.

record_once(func: Callable[[BlueprintSetupState], Callable]) → None

Used to register a deferred action that happens only once.

register(app: Quart, first_registration: bool, *, url_prefix: Optional[str] = None) → None

Register this blueprint on the app given.

register_error_handler(error: Union[Type[Exception], int], func: Callable) → None

Add an error handler function to the blueprint.

This is designed to be used on the blueprint directly, and has the same arguments as register_error_handler(). An example usage,

def not_found():
    ...

blueprint = Blueprint(__name__)
blueprint.register_error_handler(404, not_found)
route(path: str, methods: Optional[List[str]] = None, endpoint: Optional[str] = None, defaults: Optional[dict] = None, host: Optional[str] = None, subdomain: Optional[str] = None, *, provide_automatic_options: Optional[bool] = None, strict_slashes: bool = True) → Callable

Add a route to the blueprint.

This is designed to be used as a decorator, and has the same arguments as route(). An example usage,

blueprint = Blueprint(__name__)
@blueprint.route('/')
def route():
    ...
teardown_app_request(func: Callable) → Callable

Add a teardown request function to the app.

This is designed to be used as a decorator, and has the same arguments as teardown_request(). It applies to all requests to the app this blueprint is registered on. An example usage,

blueprint = Blueprint(__name__)
@blueprint.teardown_app_request
def teardown():
    ...
teardown_request(func: Callable) → Callable

Add a teardown request function to the Blueprint.

This is designed to be used as a decorator, and has the same arguments as teardown_request(). It applies only to requests that are routed to an endpoint in this blueprint. An example usage,

blueprint = Blueprint(__name__)
@blueprint.teardown_request
def teardown():
    ...
teardown_websocket(func: Callable) → Callable

Add a teardown websocket function to the Blueprint.

This is designed to be used as a decorator, and has the same arguments as teardown_websocket(). It applies only to requests that are routed to an endpoint in this blueprint. An example usage,

blueprint = Blueprint(__name__)
@blueprint.teardown_websocket
def teardown():
    ...
url_defaults(func: Callable) → Callable

Add a url default preprocessor.

This is designed to be used as a decorator, and has the same arguments as url_defaults(). This will apply to urls in this blueprint. An example usage,

blueprint = Blueprint(__name__)
@blueprint.url_defaults
def default(endpoint, values):
    ...
url_value_preprocessor(func: Callable) → Callable

Add a url value preprocessor.

This is designed to be used as a decorator, and has the same arguments as url_value_preprocessor(). This will apply to urls in this blueprint. An example usage,

blueprint = Blueprint(__name__)
@blueprint.url_value_preprocessor
def processor(endpoint, view_args):
    ...
websocket(path: str, endpoint: Optional[str] = None, defaults: Optional[dict] = None, host: Optional[str] = None, subdomain: Optional[str] = None, *, strict_slashes: bool = True) → Callable

Add a websocket to the blueprint.

This is designed to be used as a decorator, and has the same arguments as websocket(). An example usage,

blueprint = Blueprint(__name__)
@blueprint.websocket('/')
async def route():
    ...
class quart.Config(root_path: Union[bytes, str, os.PathLike], defaults: Optional[dict] = None)

Bases: dict

Extends a standard Python dictionary with additional load (from) methods.

Note that the convention (as enforced when loading) is that configuration keys are upper case. Whilst you can set lower case keys it is not recommended.

from_envvar(variable_name: str, silent: bool = False) → None

Load the configuration from a location specified in the environment.

This will load a cfg file using from_pyfile() from the location specified in the environment, for example the two blocks below are equivalent.

app.config.from_envvar('CONFIG')

filename = os.environ['CONFIG']
app.config.from_pyfile(filename)
from_file(filename: str, load: Callable[[IO[Any]], Mapping], silent: bool = False) → None

Load the configuration from a data file.

This allows configuration to be loaded as so

app.config.from_file('config.toml', toml.load)
app.config.from_file('config.json', json.load)
Parameters

  • filename – The filename which when appended to root_path gives the path to the file.

  • load – Callable that takes a file descriptor and returns a mapping loaded from the file.

  • silent – If True any errors will fail silently.

from_json(filename: str, silent: bool = False) → None

Load the configuration values from a JSON formatted file.

This allows configuration to be loaded as so

app.config.from_json('config.json')
Parameters

  • filename – The filename which when appended to root_path gives the path to the file.

  • silent – If True any errors will fail silently.

from_mapping(mapping: Optional[Mapping[str, Any]] = None, **kwargs: Any) → None

Load the configuration values from a mapping.

This allows either a mapping to be directly passed or as keyword arguments, for example,

config = {'FOO': 'bar'}
app.config.from_mapping(config)
app.config.form_mapping(FOO='bar')
Parameters

  • mapping – Optionally a mapping object.

  • kwargs – Optionally a collection of keyword arguments to form a mapping.

from_object(instance: Union[object, str]) → None

Load the configuration from a Python object.

This can be used to reference modules or objects within modules for example,

app.config.from_object('module')
app.config.from_object('module.instance')
from module import instance
app.config.from_object(instance)

are valid.

Parameters

instance – Either a str referencing a python object or the object itself.

from_pyfile(filename: str, silent: bool = False) → None

Load the configuration from a Python cfg or py file.

See Python’s ConfigParser docs for details on the cfg format. It is a common practice to load the defaults from the source using the from_object() and then override with a cfg or py file, for example

app.config.from_object('config_module')
app.config.from_pyfile('production.cfg')
Parameters

filename – The filename which when appended to root_path gives the path to the file

get_namespace(namespace: str, lowercase: bool = True, trim_namespace: bool = True) → Dict[str, Any]

Return a dictionary of keys within a namespace.

A namespace is considered to be a key prefix, for example the keys FOO_A, FOO_BAR, FOO_B are all within the FOO namespace. This method would return a dictionary with these keys and values present.

config = {'FOO_A': 'a', 'FOO_BAR': 'bar', 'BAR': False}
app.config.from_mapping(config)
assert app.config.get_namespace('FOO_') == {'a': 'a', 'bar': 'bar'}
Parameters

  • namespace – The namespace itself (should be uppercase).

  • lowercase – Lowercase the keys in the returned dictionary.

  • trim_namespace – Remove the namespace from the returned keys.

quart.copy_current_app_context(func: Callable) → Callable

Share the current app context with the function decorated.

The app context is local per task and hence will not be available in any other task. This decorator can be used to make the context available,

@copy_current_app_context
async def within_context() -> None:
    name = current_app.name
    ...
quart.copy_current_request_context(func: Callable) → Callable

Share the current request context with the function decorated.

The request context is local per task and hence will not be available in any other task. This decorator can be used to make the context available,

@copy_current_request_context
async def within_context() -> None:
    method = request.method
    ...
quart.copy_current_websocket_context(func: Callable) → Callable

Share the current websocket context with the function decorated.

The websocket context is local per task and hence will not be available in any other task. This decorator can be used to make the context available,

@copy_current_websocket_context
async def within_context() -> None:
    method = websocket.method
    ...
quart.escape(s) → markup

Convert the characters &, <, >, ‘, and ” in string s to HTML-safe sequences. Use this if you need to display text that might contain such characters in HTML. Marks return value as markup string.

async quart.flash(message: str, category: str = 'message') → None

Add a message (with optional category) to the session store.

This is typically used to flash a message to a user that will be stored in the session and shown during some other request. For example,

@app.route('/login', methods=['POST'])
async def login():
    ...
    await flash('Login successful')
    return redirect(url_for('index'))

allows the index route to show the flashed messsages, without having to accept the message as an argument or otherwise. See get_flashed_messages() for message retrieval.

quart.get_flashed_messages(with_categories: bool = False, category_filter: List[str] = []) → Union[List[str], List[Tuple[str, str]]]

Retrieve the flashed messages stored in the session.

This is mostly useful in templates where it is exposed as a global function, for example

<ul>
{% for message in get_flashed_messages() %}
  <li>{{ message }}</li>
{% endfor %}
</ul>

Note that caution is required for usage of category_filter as all messages will be popped, but only those matching the filter returned. See flash() for message creation.

quart.get_template_attribute(template_name: str, attribute: str) → Any

Load a attribute from a template.

This is useful in Python code in order to use attributes in templates.

Parameters

  • template_name – To load the attribute from.

  • attribute – The attribute name to load

quart.has_app_context() → bool

Check if execution is within an app context.

This allows a controlled way to act if there is an app context available, or silently not act if not. For example,

if has_app_context():
    log.info("Executing in %s context", current_app.name)

See also has_request_context()

quart.has_request_context() → bool

Check if execution is within a request context.

This allows a controlled way to act if there is a request context available, or silently not act if not. For example,

if has_request_context():
    log.info("Request endpoint %s", request.endpoint)

See also has_app_context().

quart.has_websocket_context() → bool

Check if execution is within a websocket context.

This allows a controlled way to act if there is a websocket context available, or silently not act if not. For example,

if has_websocket_context():
    log.info("Websocket endpoint %s", websocket.endpoint)

See also has_app_context().

quart.jsonify(*args: Any, **kwargs: Any) → Response
async quart.make_push_promise(path: str) → None

Create a push promise, a simple wrapper function.

This takes a path that should be pushed to the client if the protocol is HTTP/2.

async quart.make_response(*args: Any) → quart.wrappers.response.Response

Create a response, a simple wrapper function.

This is most useful when you want to alter a Response before returning it, for example

response = make_response(render_template('index.html'))
response.headers['X-Header'] = 'Something'
class quart.Markup

Bases: str

A string that is ready to be safely inserted into an HTML or XML document, either because it was escaped or because it was marked safe.

Passing an object to the constructor converts it to text and wraps it to mark it safe without escaping. To escape the text, use the escape() class method instead.

>>> Markup('Hello, <em>World</em>!')
Markup('Hello, <em>World</em>!')
>>> Markup(42)
Markup('42')
>>> Markup.escape('Hello, <em>World</em>!')
Markup('Hello &lt;em&gt;World&lt;/em&gt;!')

This implements the __html__() interface that some frameworks use. Passing an object that implements __html__() will wrap the output of that method, marking it safe.

>>> class Foo:
...     def __html__(self):
...         return '<a href="/foo">foo</a>'
...
>>> Markup(Foo())
Markup('<a href="/foo">foo</a>')

This is a subclass of the text type (str in Python 3, unicode in Python 2). It has the same methods as that type, but all methods escape their arguments and return a Markup instance.

>>> Markup('<em>%s</em>') % 'foo & bar'
Markup('<em>foo &amp; bar</em>')
>>> Markup('<em>Hello</em> ') + '<foo>'
Markup('<em>Hello</em> &lt;foo&gt;')
capitalize(*args, **kwargs)

Return a capitalized version of the string.

More specifically, make the first character have upper case and the rest lower case.

center(*args, **kwargs)

Return a centered string of length width.

Padding is done using the specified fill character (default is a space).

classmethod escape(s)

Escape a string. Calls escape() and ensures that for subclasses the correct type is returned.

expandtabs(*args, **kwargs)

Return a copy where all tab characters are expanded using spaces.

If tabsize is not given, a tab size of 8 characters is assumed.

format(*args, **kwargs) → str

Return a formatted version of S, using substitutions from args and kwargs. The substitutions are identified by braces (‘{‘ and ‘}’).

join(seq)

Concatenate any number of strings.

The string whose method is called is inserted in between each given string. The result is returned as a new string.

Example: ‘.’.join([‘ab’, ‘pq’, ‘rs’]) -> ‘ab.pq.rs’

ljust(*args, **kwargs)

Return a left-justified string of length width.

Padding is done using the specified fill character (default is a space).

lower(*args, **kwargs)

Return a copy of the string converted to lowercase.

lstrip(*args, **kwargs)

Return a copy of the string with leading whitespace removed.

If chars is given and not None, remove characters in chars instead.

partition(sep)

Partition the string into three parts using the given separator.

This will search for the separator in the string. If the separator is found, returns a 3-tuple containing the part before the separator, the separator itself, and the part after it.

If the separator is not found, returns a 3-tuple containing the original string and two empty strings.

replace(*args, **kwargs)

Return a copy with all occurrences of substring old replaced by new.

count

Maximum number of occurrences to replace. -1 (the default value) means replace all occurrences.

If the optional argument count is given, only the first count occurrences are replaced.

rjust(*args, **kwargs)

Return a right-justified string of length width.

Padding is done using the specified fill character (default is a space).

rpartition(sep)

Partition the string into three parts using the given separator.

This will search for the separator in the string, starting at the end. If the separator is found, returns a 3-tuple containing the part before the separator, the separator itself, and the part after it.

If the separator is not found, returns a 3-tuple containing two empty strings and the original string.

rsplit(*args, **kwargs)

Return a list of the words in the string, using sep as the delimiter string.

sep

The delimiter according which to split the string. None (the default value) means split according to any whitespace, and discard empty strings from the result.

maxsplit

Maximum number of splits to do. -1 (the default value) means no limit.

Splits are done starting at the end of the string and working to the front.

rstrip(*args, **kwargs)

Return a copy of the string with trailing whitespace removed.

If chars is given and not None, remove characters in chars instead.

split(*args, **kwargs)

Return a list of the words in the string, using sep as the delimiter string.

sep

The delimiter according which to split the string. None (the default value) means split according to any whitespace, and discard empty strings from the result.

maxsplit

Maximum number of splits to do. -1 (the default value) means no limit.

splitlines(*args, **kwargs)

Return a list of the lines in the string, breaking at line boundaries.

Line breaks are not included in the resulting list unless keepends is given and true.

strip(*args, **kwargs)

Return a copy of the string with leading and trailing whitespace removed.

If chars is given and not None, remove characters in chars instead.

striptags()

unescape() the markup, remove tags, and normalize whitespace to single spaces.

>>> Markup('Main &raquo;        <em>About</em>').striptags()
'Main » About'
swapcase(*args, **kwargs)

Convert uppercase characters to lowercase and lowercase characters to uppercase.

title(*args, **kwargs)

Return a version of the string where each word is titlecased.

More specifically, words start with uppercased characters and all remaining cased characters have lower case.

translate(*args, **kwargs)

Replace each character in the string using the given translation table.

table

Translation table, which must be a mapping of Unicode ordinals to Unicode ordinals, strings, or None.

The table must implement lookup/indexing via __getitem__, for instance a dictionary or list. If this operation raises LookupError, the character is left untouched. Characters mapped to None are deleted.

unescape()

Convert escaped markup back into a text string. This replaces HTML entities with the characters they represent.

>>> Markup('Main &raquo; <em>About</em>').unescape()
'Main » <em>About</em>'
upper(*args, **kwargs)

Return a copy of the string converted to uppercase.

zfill(*args, **kwargs)

Pad a numeric string with zeros on the left, to fill a field of the given width.

The string is never truncated.

class quart.Quart(import_name: str, static_url_path: Optional[str] = None, static_folder: Optional[str] = 'static', static_host: Optional[str] = None, host_matching: bool = False, subdomain_matching: bool = False, template_folder: Optional[str] = 'templates', root_path: Optional[str] = None, instance_path: Optional[str] = None, instance_relative_config: bool = False)

Bases: quart.static.PackageStatic

The web framework class, handles requests and returns responses.

The primary method from a serving viewpoint is handle_request(), from an application viewpoint all the other methods are vital.

This can be extended in many ways, with most methods designed with this in mind. Additionally any of the classes listed as attributes can be replaced.

app_ctx_globals_class

The class to use for the g object

asgi_http_class

The class to use to handle the ASGI HTTP protocol.

asgi_lifespan_class

The class to use to handle the ASGI lifespan protocol.

asgi_websocket_class

The class to use to handle the ASGI websocket protocol.

config_class

The class to use for the configuration.

env

The name of the environment the app is running on.

debug

Wrapper around configuration DEBUG value, in many places this will result in more output if True. If unset, debug mode will be activated if environ is set to ‘development’.

jinja_environment

The class to use for the jinja environment.

jinja_options

The default options to set when creating the jinja environment.

json_decoder

The decoder for JSON data.

json_encoder

The encoder for JSON data.

permanent_session_lifetime

Wrapper around configuration PERMANENT_SESSION_LIFETIME value. Specifies how long the session data should survive.

request_class

The class to use for requests.

response_class

The class to user for responses.

secret_key

Warpper around configuration SECRET_KEY value. The app secret for signing sessions.

Wrapper around configuration SESSION_COOKIE_NAME, use to specify the cookie name for session data.

session_interface

The class to use as the session interface.

url_map_class

The class to map rules to endpoints.

url_rule_class

The class to use for URL rules.

websocket_class

The class to use for websockets.

add_template_filter(func: Callable, name: Optional[str] = None) → None

Add a template filter.

This is designed to be used on the application directly. An example usage,

def to_upper(value):
    return value.upper()

app.add_template_filter(to_upper)
Parameters

  • func – The function that is the filter.

  • name – The filter name (defaults to function name).

add_template_global(func: Callable, name: Optional[str] = None) → None

Add a template global.

This is designed to be used on the application directly. An example usage,

def five():
    return 5

app.add_template_global(five)
Parameters

  • func – The function that is the global.

  • name – The global name (defaults to function name).

add_template_test(func: Callable, name: Optional[str] = None) → None

Add a template test.

This is designed to be used on the application directly. An example usage,

def is_upper(value):
    return value.isupper()

app.add_template_test(is_upper)
Parameters

  • func – The function that is the test.

  • name – The test name (defaults to function name).

add_url_rule(path: str, endpoint: Optional[str] = None, view_func: Optional[Callable] = None, methods: Optional[Iterable[str]] = None, defaults: Optional[dict] = None, host: Optional[str] = None, subdomain: Optional[str] = None, *, provide_automatic_options: Optional[bool] = None, is_websocket: bool = False, strict_slashes: bool = True, merge_slashes: Optional[bool] = None) → None

Add a route/url rule to the application.

This is designed to be used on the application directly. An example usage,

def route():
    ...

app.add_url_rule('/', route)
Parameters

  • path – The path to route on, should start with a /.

  • func – Callable that returns a response.

  • methods – List of HTTP verbs the function routes.

  • endpoint – Optional endpoint name, if not present the function name is used.

  • defaults –

    A dictionary of variables to provide automatically, use to provide a simpler default path for a route, e.g. to allow for /book rather than /book/0,

    @app.route('/book', defaults={'page': 0})
@app.route('/book/<int:page>')
def book(page):
    ...

  • host – The full host name for this route (should include subdomain if needed) - cannot be used with subdomain.

  • subdomain – A subdomain for this specific route.

  • provide_automatic_options – Optionally False to prevent OPTION handling.

  • strict_slashes – Strictly match the trailing slash present in the path. Will redirect a leaf (no slash) to a branch (with slash).

  • merge_slashes – Merge consecutive slashes to a single slash (unless as part of the path variable).

add_websocket(path: str, endpoint: Optional[str] = None, view_func: Optional[Callable] = None, defaults: Optional[dict] = None, host: Optional[str] = None, subdomain: Optional[str] = None, *, strict_slashes: bool = True) → None

Add a websocket url rule to the application.

This is designed to be used on the application directly. An example usage,

def websocket_route():
    ...

app.add_websocket('/', websocket_route)
Parameters

  • path – The path to route on, should start with a /.

  • func – Callable that returns a response.

  • endpoint – Optional endpoint name, if not present the function name is used.

  • defaults –

    A dictionary of variables to provide automatically, use to provide a simpler default path for a route, e.g. to allow for /book rather than /book/0,

    @app.websocket('/book', defaults={'page': 0})
@app.websocket('/book/<int:page>')
def book(page):
    ...

  • host – The full host name for this route (should include subdomain if needed) - cannot be used with subdomain.

  • subdomain – A subdomain for this specific route.

  • strict_slashes – Strictly match the trailing slash present in the path. Will redirect a leaf (no slash) to a branch (with slash).

after_request(func: Union[Callable[[quart.wrappers.response.Response], quart.wrappers.response.Response], Callable[[quart.wrappers.response.Response], Awaitable[quart.wrappers.response.Response]]], name: Optional[str] = None) → Callable[[quart.wrappers.response.Response], Awaitable[None]]

Add an after request function.

This is designed to be used as a decorator, if used to decorate a synchronous function, the function will be wrapped in run_sync() and run in a thread executor (with the wrapped function returned). An example usage,

@app.after_request
async def func(response):
    return response
Parameters

  • func – The after request function itself.

  • name – Optional blueprint key name.

after_serving(func: Union[Callable[[], None], Callable[[], Awaitable[None]]]) → Callable[[], Awaitable[None]]

Add a after serving function.

This will allow the function provided to be called once after anything is served (after last byte is sent).

This is designed to be used as a decorator, if used to decorate a synchronous function, the function will be wrapped in run_sync() and run in a thread executor (with the wrapped function returned). An example usage,

@app.after_serving
async def func():
    ...
Parameters

func – The function itself.

after_websocket(func: Union[Callable[[quart.wrappers.response.Response], Optional[quart.wrappers.response.Response]], Callable[[quart.wrappers.response.Response], Awaitable[Optional[quart.wrappers.response.Response]]]], name: Optional[str] = None) → Callable[[quart.wrappers.response.Response], Awaitable[None]]

Add an after websocket function.

This is designed to be used as a decorator, if used to decorate a synchronous function, the function will be wrapped in run_sync() and run in a thread executor (with the wrapped function returned). An example usage,

@app.after_websocket
async def func(response):
    return response
Parameters

  • func – The after websocket function itself.

  • name – Optional blueprint key name.

app_context() → quart.ctx.AppContext

Create and return an app context.

This is best used within a context, i.e.

async with app.app_context():
    ...
app_ctx_globals_class

alias of quart.ctx._AppCtxGlobals

async asgi_app(scope: dict, receive: Callable, send: Callable) → None

This handles ASGI calls, it can be wrapped in middleware.

When using middleware with Quart it is preferable to wrap this method rather than the app itself. This is to ensure that the app is an instance of this class - which allows the quart cli to work correctly. To use this feature simply do,

app.asgi_app = middleware(app.asgi_app)
asgi_http_class

alias of quart.asgi.ASGIHTTPConnection

asgi_lifespan_class

alias of quart.asgi.ASGILifespan

asgi_websocket_class

alias of quart.asgi.ASGIWebsocketConnection

auto_find_instance_path() → pathlib.Path

Locates the instace_path if it was not provided

before_first_request(func: Union[Callable[[], None], Callable[[], Awaitable[None]]], name: Optional[str] = None) → Callable[[], Awaitable[None]]

Add a before first request function.

This is designed to be used as a decorator, if used to decorate a synchronous function, the function will be wrapped in run_sync() and run in a thread executor (with the wrapped function returned). An example usage,

@app.before_first_request
async def func():
    ...
Parameters

  • func – The before first request function itself.

  • name – Optional blueprint key name.

before_request(func: Union[Callable[[], None], Callable[[], Awaitable[None]]], name: Optional[str] = None) → Callable[[], Awaitable[None]]

Add a before request function.

This is designed to be used as a decorator, if used to decorate a synchronous function, the function will be wrapped in run_sync() and run in a thread executor (with the wrapped function returned). An example usage,

@app.before_request
async def func():
    ...
Parameters

  • func – The before request function itself.

  • name – Optional blueprint key name.

before_serving(func: Union[Callable[[], None], Callable[[], Awaitable[None]]]) → Callable[[], Awaitable[None]]

Add a before serving function.

This will allow the function provided to be called once before anything is served (before any byte is received).

This is designed to be used as a decorator, if used to decorate a synchronous function, the function will be wrapped in run_sync() and run in a thread executor (with the wrapped function returned). An example usage,

@app.before_serving
async def func():
    ...
Parameters

func – The function itself.

before_websocket(func: Union[Callable[[], None], Callable[[], Awaitable[None]]], name: Optional[str] = None) → Callable[[], Awaitable[None]]

Add a before websocket function.

This is designed to be used as a decorator, if used to decorate a synchronous function, the function will be wrapped in run_sync() and run in a thread executor (with the wrapped function returned). An example usage,

@app.before_websocket
async def func():
    ...
Parameters

  • func – The before websocket function itself.

  • name – Optional blueprint key name.

config_class

alias of quart.config.Config

context_processor(func: Union[Callable[[], Dict[str, Any]], Callable[[], Awaitable[Dict[str, Any]]]], name: Optional[str] = None) → Callable[[], Awaitable[Dict[str, Any]]]

Add a template context processor.

This is designed to be used as a decorator, if used to decorate a synchronous function, the function will be wrapped in run_sync() and run in a thread executor (with the wrapped function returned). An example usage,

@app.context_processor
async def update_context(context):
    return context
create_global_jinja_loader() → quart.templating.DispatchingJinjaLoader

Create and return a global (not blueprint specific) Jinja loader.

create_jinja_environment() → quart.templating.Environment

Create and return the jinja environment.

This will create the environment based on the jinja_options and configuration settings. The environment will include the Quart globals by default.

create_url_adapter(request: Optional[quart.wrappers.base.BaseRequestWebsocket]) → Optional[werkzeug.routing.MapAdapter]

Create and return a URL adapter.

This will create the adapter based on the request if present otherwise the app configuration.

debug

Implements a property descriptor for objects with a config attribute.

When used as a class instance it will look up the key on the class config object, for example:

class Object:
    config = {}
    foo = ConfigAttribute('foo')

obj = Object()
obj.foo = 'bob'
assert obj.foo == obj.config['foo']
async dispatch_request(request_context: Optional[quart.ctx.RequestContext] = None) → Union[Response, str, Dict[str, Any], AsyncGenerator[bytes, None], Generator[bytes, None, None], Tuple[Union[Response, str, Dict[str, Any], AsyncGenerator[bytes, None], Generator[bytes, None, None]], dict], Tuple[Union[Response, str, Dict[str, Any], AsyncGenerator[bytes, None], Generator[bytes, None, None]], int], Tuple[Union[Response, str, Dict[str, Any], AsyncGenerator[bytes, None], Generator[bytes, None, None]], int, dict]]

Dispatch the request to the view function.

Parameters

request_context – The request context, optional as Flask omits this argument.

async dispatch_websocket(websocket_context: Optional[quart.ctx.WebsocketContext] = None) → None

Dispatch the websocket to the view function.

Parameters

websocket_context – The websocket context, optional to match the Flask convention.

async do_teardown_appcontext(exc: Optional[BaseException]) → None

Teardown the app (context), calling the teardown functions.

async do_teardown_request(exc: Optional[BaseException], request_context: Optional[quart.ctx.RequestContext] = None) → None

Teardown the request, calling the teardown functions.

Parameters

  • exc – Any exception not handled that has caused the request to teardown.

  • request_context – The request context, optional as Flask omits this argument.

async do_teardown_websocket(exc: Optional[BaseException], websocket_context: Optional[quart.ctx.WebsocketContext] = None) → None

Teardown the websocket, calling the teardown functions.

Parameters

  • exc – Any exception not handled that has caused the websocket to teardown.

  • websocket_context – The websocket context, optional as Flask omits this argument.

endpoint(endpoint: str) → Callable

Register a function as an endpoint.

This is designed to be used as a decorator, if used to decorate a synchronous function, the function will be wrapped in run_sync() and run in a thread executor (with the wrapped function returned). An example usage,

@app.endpoint('name')
async def endpoint():
    ...
Parameters

endpoint – The endpoint name to use.

ensure_async(func: Callable[[...], Any]) → Callable[[...], Awaitable[Any]]

Ensure that the returned func is async and calls the func.

New in version 0.11.

Override if you wish to change how synchronous functions are run. Before Quart 0.11 this did not run the synchronous code in an executor.

env

Implements a property descriptor for objects with a config attribute.

When used as a class instance it will look up the key on the class config object, for example:

class Object:
    config = {}
    foo = ConfigAttribute('foo')

obj = Object()
obj.foo = 'bob'
assert obj.foo == obj.config['foo']
errorhandler(error: Union[Type[Exception], int]) → Callable

Register a function as an error handler.

This is designed to be used as a decorator. An example usage,

@app.errorhandler(500)
def error_handler():
    return "Error", 500
Parameters

error – The error code or Exception to handle.

async finalize_request(result: Union[Response, str, Dict[str, Any], AsyncGenerator[bytes, None], Generator[bytes, None, None], Tuple[Union[Response, str, Dict[str, Any], AsyncGenerator[bytes, None], Generator[bytes, None, None]], dict], Tuple[Union[Response, str, Dict[str, Any], AsyncGenerator[bytes, None], Generator[bytes, None, None]], int], Tuple[Union[Response, str, Dict[str, Any], AsyncGenerator[bytes, None], Generator[bytes, None, None]], int, dict]], request_context: Optional[quart.ctx.RequestContext] = None, from_error_handler: bool = False) → quart.wrappers.response.Response

Turns the view response return value into a response.

Parameters

  • result – The result of the request to finalize into a response.

  • request_context – The request context, optional as Flask omits this argument.

async finalize_websocket(result: Union[Response, str, Dict[str, Any], AsyncGenerator[bytes, None], Generator[bytes, None, None], Tuple[Union[Response, str, Dict[str, Any], AsyncGenerator[bytes, None], Generator[bytes, None, None]], dict], Tuple[Union[Response, str, Dict[str, Any], AsyncGenerator[bytes, None], Generator[bytes, None, None]], int], Tuple[Union[Response, str, Dict[str, Any], AsyncGenerator[bytes, None], Generator[bytes, None, None]], int, dict]], websocket_context: Optional[quart.ctx.WebsocketContext] = None, from_error_handler: bool = False) → Optional[quart.wrappers.response.Response]

Turns the view response return value into a response.

Parameters

  • result – The result of the websocket to finalize into a response.

  • websocket_context – The websocket context, optional as Flask omits this argument.

async full_dispatch_request(request_context: Optional[quart.ctx.RequestContext] = None) → quart.wrappers.response.Response

Adds pre and post processing to the request dispatching.

Parameters

request_context – The request context, optional as Flask omits this argument.

async full_dispatch_websocket(websocket_context: Optional[quart.ctx.WebsocketContext] = None) → Optional[quart.wrappers.response.Response]

Adds pre and post processing to the websocket dispatching.

Parameters

websocket_context – The websocket context, optional to match the Flask convention.

property got_first_request

Return if the app has received a request.

async handle_exception(error: Exception) → quart.wrappers.response.Response

Handle an uncaught exception.

By default this switches the error response to a 500 internal server error.

async handle_http_exception(error: Exception) → quart.wrappers.response.Response

Handle a HTTPException subclass error.

This will attempt to find a handler for the error and if fails will fall back to the error response.

async handle_request(request: quart.wrappers.request.Request) → quart.wrappers.response.Response
handle_url_build_error(error: Exception, endpoint: str, values: dict) → str

Handle a build error.

Ideally this will return a valid url given the error endpoint and values.

async handle_user_exception(error: Exception) → quart.wrappers.response.Response

Handle an exception that has been raised.

This should forward HTTPException to handle_http_exception(), then attempt to handle the error. If it cannot it should reraise the error.

async handle_websocket(websocket: quart.wrappers.request.Websocket) → Optional[quart.wrappers.response.Response]
async handle_websocket_exception(error: Exception) → Optional[quart.wrappers.response.Response]

Handle an uncaught exception.

By default this logs the exception and then re-raises it.

inject_url_defaults(endpoint: str, values: dict) → None

Injects default URL values into the passed values dict.

This is used to assist when building urls, see url_for().

iter_blueprints() → ValuesView[quart.blueprints.Blueprint]

Return a iterator over the blueprints.

property jinja_env

The jinja environment used to load templates.

jinja_environment

alias of quart.templating.Environment

jinja_options = {'autoescape': True, 'extensions': ['jinja2.ext.autoescape', 'jinja2.ext.with_']}
json_decoder

alias of quart.json.JSONDecoder

json_encoder

alias of quart.json.JSONEncoder

lock_class

alias of asyncio.locks.Lock

log_exception(exception_info: Tuple[type, BaseException, traceback]) → None

Log a exception to the logger.

By default this is only invoked for unhandled exceptions.

property logger

A logging.Logger logger for the app.

This can be used to log messages in a format as defined in the app configuration, for example,

app.logger.debug("Request method %s", request.method)
app.logger.error("Error, of some kind")
make_config(instance_relative: bool = False) → quart.config.Config

Create and return the configuration with appropriate defaults.

async make_default_options_response() → quart.wrappers.response.Response

This is the default route function for OPTIONS requests.

async make_null_session() → quart.sessions.Session

Create and return a null session.

async make_response(result: Union[Response, str, Dict[str, Any], AsyncGenerator[bytes, None], Generator[bytes, None, None], Tuple[Union[Response, str, Dict[str, Any], AsyncGenerator[bytes, None], Generator[bytes, None, None]], dict], Tuple[Union[Response, str, Dict[str, Any], AsyncGenerator[bytes, None], Generator[bytes, None, None]], int], Tuple[Union[Response, str, Dict[str, Any], AsyncGenerator[bytes, None], Generator[bytes, None, None]], int, dict]]) → quart.wrappers.response.Response

Make a Response from the result of the route handler.

The result itself can either be:

  • A Response object (or subclass).

  • A tuple of a ResponseValue and a header dictionary.

  • A tuple of a ResponseValue, status code and a header dictionary.

A ResponseValue is either a Response object (or subclass) or a str.

make_shell_context() → dict

Create a context for interactive shell usage.

The shell_context_processors can be used to add additional context.

property name

The name of this application.

This is taken from the import_name and is used for debugging purposes.

open_instance_resource(path: Union[bytes, str, os.PathLike], mode: str = 'rb') → IO[AnyStr]

Open a file for reading.

Use as

with app.open_instance_resouce(path) as file_:
    file_.read()
async open_session(request: quart.wrappers.base.BaseRequestWebsocket) → quart.sessions.Session

Open and return a Session using the request.

permanent_session_lifetime

Implements a property descriptor for objects with a config attribute.

When used as a class instance it will look up the key on the class config object, for example:

class Object:
    config = {}
    foo = ConfigAttribute('foo')

obj = Object()
obj.foo = 'bob'
assert obj.foo == obj.config['foo']
async postprocess_websocket(response: Optional[quart.wrappers.response.Response], websocket_context: Optional[quart.ctx.WebsocketContext] = None) → quart.wrappers.response.Response

Postprocess the websocket acting on the response.

Parameters

  • response – The response after the websocket is finalized.

  • webcoket_context – The websocket context, optional as Flask omits this argument.

async preprocess_request(request_context: Optional[quart.ctx.RequestContext] = None) → Union[Response, str, Dict[str, Any], AsyncGenerator[bytes, None], Generator[bytes, None, None], Tuple[Union[Response, str, Dict[str, Any], AsyncGenerator[bytes, None], Generator[bytes, None, None]], dict], Tuple[Union[Response, str, Dict[str, Any], AsyncGenerator[bytes, None], Generator[bytes, None, None]], int], Tuple[Union[Response, str, Dict[str, Any], AsyncGenerator[bytes, None], Generator[bytes, None, None]], int, dict], None]

Preprocess the request i.e. call before_request functions.

Parameters

request_context – The request context, optional as Flask omits this argument.

async preprocess_websocket(websocket_context: Optional[quart.ctx.WebsocketContext] = None) → Union[Response, str, Dict[str, Any], AsyncGenerator[bytes, None], Generator[bytes, None, None], Tuple[Union[Response, str, Dict[str, Any], AsyncGenerator[bytes, None], Generator[bytes, None, None]], dict], Tuple[Union[Response, str, Dict[str, Any], AsyncGenerator[bytes, None], Generator[bytes, None, None]], int], Tuple[Union[Response, str, Dict[str, Any], AsyncGenerator[bytes, None], Generator[bytes, None, None]], int, dict], None]

Preprocess the websocket i.e. call before_websocket functions.

Parameters

websocket_context – The websocket context, optional as Flask omits this argument.

async process_response(response: quart.wrappers.response.Response, request_context: Optional[quart.ctx.RequestContext] = None) → quart.wrappers.response.Response

Postprocess the request acting on the response.

Parameters

  • response – The response after the request is finalized.

  • request_context – The request context, optional as Flask omits this argument.

property propagate_exceptions

Return true if exceptions should be propagated into debug pages.

If false the exception will be handled. See the PROPAGATE_EXCEPTIONS config settin.

register_blueprint(blueprint: quart.blueprints.Blueprint, url_prefix: Optional[str] = None) → None

Register a blueprint on the app.

This results in the blueprint’s routes, error handlers etc… being added to the app.

Parameters

  • blueprint – The blueprint to register.

  • url_prefix – Optional prefix to apply to all paths.

register_error_handler(error: Union[Type[Exception], int], func: Union[Callable[[Exception], None], Callable[[Exception], Awaitable[None]]], name: Optional[str] = None) → None

Register a function as an error handler.

This is designed to be used on the application directly. An example usage,

def error_handler():
    return "Error", 500

app.register_error_handler(500, error_handler)
Parameters

  • error – The error code or Exception to handle.

  • func – The function to handle the error.

  • name – Optional blueprint key name.

request_class

alias of quart.wrappers.request.Request

request_context(request: quart.wrappers.request.Request) → quart.ctx.RequestContext

Create and return a request context.

Use the test_request_context() whilst testing. This is best used within a context, i.e.

async with app.request_context(request):
    ...
Parameters

request – A request to build a context around.

response_class

alias of quart.wrappers.response.Response

route(path: str, methods: Optional[List[str]] = None, endpoint: Optional[str] = None, defaults: Optional[dict] = None, host: Optional[str] = None, subdomain: Optional[str] = None, *, provide_automatic_options: Optional[bool] = None, strict_slashes: bool = True) → Callable

Add a route to the application.

This is designed to be used as a decorator, if used to decorate a synchronous function, the function will be wrapped in run_sync() and run in a thread executor (with the wrapped function returned). An example usage,

@app.route('/')
async def route():
    ...
Parameters

  • path – The path to route on, should start with a /.

  • methods – List of HTTP verbs the function routes.

  • defaults –

    A dictionary of variables to provide automatically, use to provide a simpler default path for a route, e.g. to allow for /book rather than /book/0,

    @app.route('/book', defaults={'page': 0})
@app.route('/book/<int:page>')
def book(page):
    ...

  • host – The full host name for this route (should include subdomain if needed) - cannot be used with subdomain.

  • subdomain – A subdomain for this specific route.

  • provide_automatic_options – Optionally False to prevent OPTION handling.

  • strict_slashes – Strictly match the trailing slash present in the path. Will redirect a leaf (no slash) to a branch (with slash).

run(host: str = '127.0.0.1', port: int = 5000, debug: Optional[bool] = None, use_reloader: bool = True, loop: Optional[asyncio.events.AbstractEventLoop] = None, ca_certs: Optional[str] = None, certfile: Optional[str] = None, keyfile: Optional[str] = None, **kwargs: Any) → None

Run this application.

This is best used for development only, see Hypercorn for production servers.

Parameters

  • host – Hostname to listen on. By default this is loopback only, use 0.0.0.0 to have the server listen externally.

  • port – Port number to listen on.

  • debug – If set enable (or disable) debug mode and debug output.

  • use_reloader – Automatically reload on code changes.

  • loop – Asyncio loop to create the server in, if None, take default one. If specified it is the caller’s responsibility to close and cleanup the loop.

  • ca_certs – Path to the SSL CA certificate file.

  • certfile – Path to the SSL certificate file.

  • keyfile – Path to the SSL key file.

run_task(host: str = '127.0.0.1', port: int = 5000, debug: Optional[bool] = None, use_reloader: bool = True, ca_certs: Optional[str] = None, certfile: Optional[str] = None, keyfile: Optional[str] = None, shutdown_trigger: Optional[Callable[[...], Awaitable[None]]] = None) → Coroutine[None, None, None]

Return a task that when awaited runs this application.

This is best used for development only, see Hypercorn for production servers.

Parameters

  • host – Hostname to listen on. By default this is loopback only, use 0.0.0.0 to have the server listen externally.

  • port – Port number to listen on.

  • debug – If set enable (or disable) debug mode and debug output.

  • use_reloader – Automatically reload on code changes.

  • loop – Asyncio loop to create the server in, if None, take default one. If specified it is the caller’s responsibility to close and cleanup the loop.

  • ca_certs – Path to the SSL CA certificate file.

  • certfile – Path to the SSL certificate file.

  • keyfile – Path to the SSL key file.

async save_session(session: quart.sessions.Session, response: quart.wrappers.response.Response) → None

Saves the session to the response.

secret_key

Implements a property descriptor for objects with a config attribute.

When used as a class instance it will look up the key on the class config object, for example:

class Object:
    config = {}
    foo = ConfigAttribute('foo')

obj = Object()
obj.foo = 'bob'
assert obj.foo == obj.config['foo']
select_jinja_autoescape(filename: str) → bool

Returns True if the filename indicates that it should be escaped.

send_file_max_age_default

Implements a property descriptor for objects with a config attribute.

When used as a class instance it will look up the key on the class config object, for example:

class Object:
    config = {}
    foo = ConfigAttribute('foo')

obj = Object()
obj.foo = 'bob'
assert obj.foo == obj.config['foo']
session_cookie_name

Implements a property descriptor for objects with a config attribute.

When used as a class instance it will look up the key on the class config object, for example:

class Object:
    config = {}
    foo = ConfigAttribute('foo')

obj = Object()
obj.foo = 'bob'
assert obj.foo == obj.config['foo']
session_interface = <quart.sessions.SecureCookieSessionInterface object>
shell_context_processor(func: Callable[[], None]) → Callable

Add a shell context processor.

This is designed to be used as a decorator. An example usage,

@app.shell_context_processor
def additional_context():
    return context
async shutdown() → None
async startup() → None
teardown_appcontext(func: Union[Callable[[Optional[BaseException]], None], Callable[[Optional[BaseException]], Awaitable[None]]]) → Callable[[Optional[BaseException]], Awaitable[None]]

Add a teardown app (context) function.

This is designed to be used as a decorator, if used to decorate a synchronous function, the function will be wrapped in run_sync() and run in a thread executor (with the wrapped function returned). An example usage,

@app.teardown_appcontext
async def func():
    ...
Parameters

  • func – The teardown function itself.

  • name – Optional blueprint key name.

teardown_request(func: Union[Callable[[Optional[BaseException]], None], Callable[[Optional[BaseException]], Awaitable[None]]], name: Optional[str] = None) → Callable[[Optional[BaseException]], Awaitable[None]]

Add a teardown request function.

This is designed to be used as a decorator, if used to decorate a synchronous function, the function will be wrapped in run_sync() and run in a thread executor (with the wrapped function returned). An example usage,

@app.teardown_request
async def func():
    ...
Parameters

  • func – The teardown request function itself.

  • name – Optional blueprint key name.

teardown_websocket(func: Union[Callable[[Optional[BaseException]], None], Callable[[Optional[BaseException]], Awaitable[None]]], name: Optional[str] = None) → Callable[[Optional[BaseException]], Awaitable[None]]

Add a teardown websocket function.

This is designed to be used as a decorator, if used to decorate a synchronous function, the function will be wrapped in run_sync() and run in a thread executor (with the wrapped function returned). An example usage,

@app.teardown_websocket
async def func():
    ...
Parameters

  • func – The teardown websocket function itself.

  • name – Optional blueprint key name.

template_filter(name: Optional[str] = None) → Callable

Add a template filter.

This is designed to be used as a decorator. An example usage,

@app.template_filter('name')
def to_upper(value):
    return value.upper()
Parameters

name – The filter name (defaults to function name).

template_global(name: Optional[str] = None) → Callable

Add a template global.

This is designed to be used as a decorator. An example usage,

@app.template_global('name')
def five():
    return 5
Parameters

name – The global name (defaults to function name).

template_test(name: Optional[str] = None) → Callable

Add a template test.

This is designed to be used as a decorator. An example usage,

@app.template_test('name')
def is_upper(value):
    return value.isupper()
Parameters

name – The test name (defaults to function name).

test_client() → quart.testing.QuartClient

Creates and returns a test client.

test_client_class

alias of quart.testing.QuartClient

test_request_context(path: str, *, method: str = 'GET', headers: Union[dict, werkzeug.datastructures.Headers, None] = None, query_string: Optional[dict] = None, scheme: str = 'http', send_push_promise: Callable[[str, werkzeug.datastructures.Headers], Awaitable[None]] = <function no_op_push>, data: Optional[AnyStr] = None, form: Optional[dict] = None, json: Any = <object object>, root_path: str = '', http_version: str = '1.1') → quart.ctx.RequestContext

Create a request context for testing purposes.

This is best used for testing code within request contexts. It is a simplified wrapper of request_context(). It is best used in a with block, i.e.

async with app.test_request_context("/", method="GET"):
    ...
Parameters

  • path – Request path.

  • method – HTTP verb

  • headers – Headers to include in the request.

  • query_string – To send as a dictionary, alternatively the query_string can be determined from the path.

  • scheme – Scheme for the request, default http.

testing

Implements a property descriptor for objects with a config attribute.

When used as a class instance it will look up the key on the class config object, for example:

class Object:
    config = {}
    foo = ConfigAttribute('foo')

obj = Object()
obj.foo = 'bob'
assert obj.foo == obj.config['foo']
trap_http_exception(error: Exception) → bool

Check it error is http and should be trapped.

Trapped errors are not handled by the handle_http_exception(), but instead trapped by the outer most (or user handlers). This can be useful when debuging to allow tracebacks to be viewed by the debug page.

async try_trigger_before_first_request_functions() → None

Trigger the before first request methods.

async update_template_context(context: dict) → None

Update the provided template context.

This adds additional context from the various template context processors.

Parameters

context – The context to update (mutate).

url_defaults(func: Callable, name: Optional[str] = None) → Callable

Add a url default preprocessor.

This is designed to be used as a decorator. An example usage,

@app.url_defaults
def default(endpoint, values):
    ...
url_map_class

alias of quart.routing.QuartMap

url_rule_class

alias of quart.routing.QuartRule

url_value_preprocessor(func: Callable[[str, dict], None], name: Optional[str] = None) → Callable

Add a url value preprocessor.

This is designed to be used as a decorator. An example usage,

@app.url_value_preprocessor
def value_preprocessor(endpoint, view_args):
    ...
websocket(path: str, endpoint: Optional[str] = None, defaults: Optional[dict] = None, host: Optional[str] = None, subdomain: Optional[str] = None, *, strict_slashes: bool = True) → Callable

Add a websocket to the application.

This is designed to be used as a decorator, if used to decorate a synchronous function, the function will be wrapped in run_sync() and run in a thread executor (with the wrapped function returned). An example usage,

@app.websocket('/')
async def websocket_route():
    ...
Parameters

  • path – The path to route on, should start with a /.

  • defaults –

    A dictionary of variables to provide automatically, use to provide a simpler default path for a route, e.g. to allow for /book rather than /book/0,

    @app.websocket('/book', defaults={'page': 0})
@app.websocket('/book/<int:page>')
def book(page):
    ...

  • host – The full host name for this route (should include subdomain if needed) - cannot be used with subdomain.

  • subdomain – A subdomain for this specific route.

  • strict_slashes – Strictly match the trailing slash present in the path. Will redirect a leaf (no slash) to a branch (with slash).

websocket_class

alias of quart.wrappers.request.Websocket

websocket_context(websocket: quart.wrappers.request.Websocket) → quart.ctx.WebsocketContext

Create and return a websocket context.

Use the test_websocket_context() whilst testing. This is best used within a context, i.e.

async with app.websocket_context(websocket):
    ...
Parameters

websocket – A websocket to build a context around.

quart.redirect(location: str, code: int = 302) → Response
async quart.render_template(template_name_or_list: Union[str, List[str]], **context: Any) → str

Render the template with the context given.

Parameters

  • template_name_or_list – Template name to render of a list of possible template names.

  • context – The variables to pass to the template.

async quart.render_template_string(source: str, **context: Any) → str

Render the template source with the context given.

Parameters

  • source – The template source code.

  • context – The variables to pass to the template.

class quart.Request(method: str, scheme: str, path: str, query_string: bytes, headers: werkzeug.datastructures.Headers, root_path: str, http_version: str, *, max_content_length: Optional[int] = None, body_timeout: Optional[int] = None, send_push_promise: Callable[[str, werkzeug.datastructures.Headers], Awaitable[None]])

Bases: quart.wrappers.base.BaseRequestWebsocket, quart.wrappers.base.JSONMixin

This class represents a request.

It can be subclassed and the subclassed used in preference by replacing the request_class with your subclass.

body_class

The class to store the body data within.

body_class

alias of Body

property content_encoding
property content_length
property content_md5
property content_type
property data
property files

The parsed files.

This will return an empty multidict unless the request mimetype was enctype="multipart/form-data" and the method POST, PUT, or PATCH.

property form

The parsed form encoded data.

Note file data is present in the files.

async get_data(raw: bool = True) → AnyStr

The request body data.

async send_push_promise(path: str) → None
property values
class quart.Response(response: Union[quart.wrappers.response.ResponseBody, AnyStr, Iterable], status: Optional[int] = None, headers: Union[dict, werkzeug.datastructures.Headers, None] = None, mimetype: Optional[str] = None, content_type: Optional[str] = None)

Bases: quart.wrappers.base._BaseRequestResponse, quart.wrappers.base.JSONMixin

This class represents a response.

It can be subclassed and the subclassed used in preference by replacing the response_class with your subclass.

automatically_set_content_length

If False the content length header must be provided.

default_status

The status code to use if not provided.

default_mimetype

The mimetype to use if not provided.

implicit_sequence_conversion

Implicitly convert the response to a iterable in the get_data method, to allow multiple iterations.

property accept_ranges
property access_control_allow_credentials

Whether credentials can be shared by the browser to JavaScript code. As part of the preflight request it indicates whether credentials can be used on the cross origin request.

property access_control_allow_headers
property access_control_allow_methods
property access_control_allow_origin
property access_control_expose_headers
property access_control_max_age
async add_etag(overwrite: bool = False, weak: bool = False) → None
property age
property allow
automatically_set_content_length = True
property cache_control
property content_encoding
property content_language
property content_length
property content_location
property content_md5
property content_range
property content_security_policy
property content_security_policy_report_only
property content_type
data_body_class

alias of DataBody

property date
default_mimetype = 'text/html'
default_status = 200

Delete a cookie (set to expire immediately).

property expires
file_body_class

alias of FileBody

async freeze() → None

Freeze this object ready for pickling.

async get_data(raw: bool = True) → AnyStr

Return the body data.

get_etag() → Tuple[Optional[str], Optional[bool]]
implicit_sequence_conversion = True
io_body_class

alias of IOBody

iterable_body_class

alias of IterableBody

property last_modified
property location
async make_conditional(request_range: Optional[werkzeug.datastructures.Range], max_partial_size: Optional[int] = None) → None

Make the response conditional to the

Parameters

  • request_range – The range as requested by the request.

  • max_partial_size – The maximum length the server is willing to serve in a single response. Defaults to unlimited.

property referrer
property retry_after

Set a cookie in the response headers.

The arguments are the standard cookie morsels and this is a wrapper around the stdlib SimpleCookie code.

set_data(data: AnyStr) → None

Set the response data.

This will encode using the charset.

set_etag(etag: str, weak: bool = False) → None
property vary
quart.safe_join(directory: Union[bytes, str, os.PathLike], *paths: Union[bytes, str, os.PathLike]) → pathlib.Path

Safely join the paths to the known directory to return a full path.

Raises

  • NotFound – if the full path does not share a commonprefix with

  • the directory. –

async quart.send_file(filename_or_io: Union[bytes, str, os.PathLike, _io.BytesIO], mimetype: Optional[str] = None, as_attachment: bool = False, attachment_filename: Optional[str] = None, add_etags: bool = True, cache_timeout: Optional[int] = None, conditional: bool = False, last_modified: Optional[datetime.datetime] = None) → quart.wrappers.response.Response

Return a Response to send the filename given.

Parameters

  • filename_or_io – The filename (path) to send, remember to use safe_join().

  • mimetype – Mimetype to use, by default it will be guessed or revert to the DEFAULT_MIMETYPE.

  • as_attachment – If true use the attachment filename in a Content-Disposition attachment header.

  • attachment_filename – Name for the filename, if it differs

  • add_etags – Set etags based on the filename, size and modification time.

  • last_modified – Used to override the last modified value.

  • cache_timeout – Time in seconds for the response to be cached.

async quart.send_from_directory(directory: Union[bytes, str, os.PathLike], file_name: str, *, mimetype: Optional[str] = None, as_attachment: bool = False, attachment_filename: Optional[str] = None, add_etags: bool = True, cache_timeout: Optional[int] = None, conditional: bool = True, last_modified: Optional[datetime.datetime] = None) → quart.wrappers.response.Response

Send a file from a given directory.

Parameters

  • directory – Directory that when combined with file_name gives the file path.

  • file_name – File name that when combined with directory gives the file path.

See send_file() for the other arguments.

quart.stream_with_context(func: Callable) → Callable

Share the current request context with a generator.

This allows the request context to be accessed within a streaming generator, for example,

@app.route('/')
def index() -> AsyncGenerator[bytes, None]:
    @stream_with_context
    async def generator() -> bytes:
        yield request.method.encode()
        yield b' '
        yield request.path.encode()

    return generator()
quart.url_for(endpoint: str, *, _anchor: Optional[str] = None, _external: Optional[bool] = None, _method: Optional[str] = None, _scheme: Optional[str] = None, **values: Any) → str

Return the url for a specific endpoint.

This is most useful in templates and redirects to create a URL that can be used in the browser.

Parameters

  • endpoint – The endpoint to build a url for, if prefixed with . it targets endpoint’s in the current blueprint.

  • _anchor – Additional anchor text to append (i.e. #text).

  • _external – Return an absolute url for external (to app) usage.

  • _method – The method to consider alongside the endpoint.

  • _scheme – A specific scheme to use.

  • values – The values to build into the URL, as specified in the endpoint rule.