.. _raw_url_path_recipe:

Decoding Raw URL Path

This recipe demonstrates how to access the "raw" request path using non-standard (WSGI) or optional (ASGI) application server extensions. This is useful when, for instance, a URI field has been percent-encoded in order to distinguish between forward slashes inside the field's value, and slashes used to separate fields. See also: :ref:routing_encoded_slashes

WSGI

In the WSGI flavor of the framework, :attr:req.path <falcon.Request.path> is based on the PATH_INFO CGI variable, which is already presented percent-decoded. Some application servers expose the raw URL under another, non-standard, CGI variable name. Let us implement a middleware component that understands two such extensions, RAW_URI (Gunicorn, Werkzeug's dev server) and REQUEST_URI (uWSGI, Waitress, Werkzeug's dev server), and replaces req.path with a value extracted from the raw URL:

.. literalinclude:: ../../../examples/recipes/raw_url_path_wsgi.py :language: python

Running the above app with a supported server such as Gunicorn or uWSGI, the following response is rendered to a GET /cache/http%3A%2F%2Ffalconframework.org request:

.. code:: json

{
    "url": "http://falconframework.org"
}

We can also check the status of this URI in our imaginary web caching system by accessing /cache/http%3A%2F%2Ffalconframework.org/status:

.. code:: json

{
    "cached": true
}

If we removed RawPathComponent() from the app's middleware list, the request would be routed as /cache/http://falconframework.org, and no matching resource would be found:

.. code:: json

{
    "title": "404 Not Found"
}

What is more, even if we could implement a flexible router that was capable of matching these complex URI patterns, the app would still not be able to distinguish between /cache/http%3A%2F%2Ffalconframework.org%2Fstatus and /cache/http%3A%2F%2Ffalconframework.org/status if both were presented only in the percent-decoded form.

ASGI

The ASGI version of :attr:req.path <falcon.asgi.Request.path> uses the path key from the ASGI scope, where percent-encoded sequences are already decoded into characters just like in WSGI's PATH_INFO. Similar to the WSGI snippet from the previous chapter, let us create a middleware component that replaces req.path with the value of raw_path (provided the latter is present in the ASGI HTTP scope):

.. literalinclude:: ../../../examples/recipes/raw_url_path_asgi.py :language: python

Running the above snippet with uvicorn (that supports raw_path), the percent-encoded url field is now correctly handled for a GET /cache/http%3A%2F%2Ffalconframework.org%2Fstatus request:

.. code:: json

{
    "url": "http://falconframework.org/status"
}

Again, as in the WSGI version, removing RawPathComponent() no longer lets the app route the above request as intended:

.. code:: json

{
    "title": "404 Not Found"
}