Routing

Quart allows for multiple and complex routes to be defined, allowing a client to trigger specific code depending on the method and path requested.

The simplest routing is simple static rules, such as the following,

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

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

which is often sufficient for mostly static websites.

Dynamic routing

Dynamic routing can be achieved by using <variable> markers which specify that part of the route can be matched rather than pre-defined. For example,

@app.route('/page/<page_no>')
async def page(page_no):
    ...

will match paths /page/1, /page/2, and /page/jeff with the page_no argument set to '1', '2', and 'jeff' respectively.

Converters

It is often necessary and useful to specify how the variable should convert and by implication match paths. This works by adding the converter name before the variable name separated by a colon, <converter:variable>. Adapting the example above to,

@app.route('/page/<int:page_no>')
async def page(page_no):
    ...

will match paths /page/1, and /page/2 with the page_no argument set to 1, and 2 (note types) but will no longer match /page/jeff as jeff cannot be converted to an int.

The available converters are,

float	positive floating point numbers
int	positive integers
path	like string with slashes
string	(default) any text without a slash
uuid	UUID strings

note that additional converters can be added to the url_map converters dictionary.

Default values

Variable usage can sometimes prove annoying to users, for example /page/<int:page_no> will not match /page forcing the user to specify /page/1. This can be solved by specifying a default value,

@app.route('/page', defaults={'page_no': 1})
@app.route('/page/<int:page_no>')
async def page(page_no):
    ...

which allows /page to match with page_no set to 1.

Host matching, host and subdomain

Routes can be added to the app with an explicit host or subdomain to match if the app has host matching enabled. This results in the routes only matching if the host header matches, for example host='quart.com' will allow the route to match any request with a host header of quart.com and otherwise 404.

The subdomain option can only be used if the app config SERVER_NAME is set, as the host will be built up as {subdomain}.{SERVER_NAME}.

Note that the variable converters can be used in the host or subdomain options.