uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3 # v6.0.0

      - name: Check whether the citation metadata from CITATION.cff is valid
        uses: citation-file-format/cffconvert-github-action@4cf11baa70a673bfdf9dad0acc7ee33b3f4b6084 # v2.0.0
        with:

# Handling Errors { #handling-errors }

There are many situations in which you need to notify an error to a client that is using your API.

This client could be a browser with a frontend, a code from someone else, an IoT device, etc.

You could need to tell the client that:

* The client doesn't have enough privileges for that operation.
* The client doesn't have access to that resource.
* The item the client was trying to access doesn't exist.
* etc.

Taking data from:

* The path as parameters.
* Headers.
* Cookies.
* etc.

And by doing so, **FastAPI** is validating that data, converting it and generating documentation for your API automatically.

But there are situations where you might need to access the `Request` object directly.

## Details about the `Request` object { #details-about-the-request-object }

* Dem Pfad als Parameter.
* Headern.
* Cookies.
* usw.

Und indem Sie das tun, validiert **FastAPI** diese Daten, konvertiert sie und generiert automatisch Dokumentation für Ihre API.

Es gibt jedoch Situationen, in denen Sie möglicherweise direkt auf das `Request`-Objekt zugreifen müssen.

## Details zum `Request`-Objekt { #details-about-the-request-object }

        env:
            COVERAGE_FILE: coverage/.coverage.${{ runner.os }}-py${{ matrix.python-version }}
            CONTEXT: ${{ runner.os }}-py${{ matrix.python-version }}
        with:
          mode: simulation
          run: coverage run -m pytest tests/ --codspeed
      # Do not store coverage for all possible combinations to avoid file size max errors in Smokeshow
      - name: Store coverage files

<a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS" class="external-link" target="_blank">CORS or "Cross-Origin Resource Sharing"</a> refers to the situations when a frontend running in a browser has JavaScript code that communicates with a backend, and the backend is in a different "origin" than the frontend.

## Origin { #origin }

# Fehler behandeln { #handling-errors }

Es gibt viele Situationen, in denen Sie einem Client, der Ihre API nutzt, einen Fehler mitteilen müssen.

Dieser Client könnte ein Browser mit einem Frontend sein, ein Code von jemand anderem, ein IoT-Gerät usw.

Sie könnten dem Client mitteilen müssen, dass:

* Der Client nicht genügend Berechtigungen für diese Operation hat.
* Der Client keinen Zugriff auf diese Ressource hat.

Several of these are explored in the next chapters of the tutorial.

## Order matters { #order-matters }

When creating *path operations*, you can find situations where you have a fixed path.

Like `/users/me`, let's say that it's to get data about the current user.

And then you can also have a path `/users/{user_id}` to get data about a specific user by some user ID.

<a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS" class="external-link" target="_blank">CORS oder <abbr title="Ressourcenfreigabe zwischen Ursprüngen">„Cross-Origin Resource Sharing“</abbr></a> bezieht sich auf Situationen, in denen ein Frontend, das in einem Browser läuft, JavaScript-Code enthält, der mit einem Backend kommuniziert, und das Backend sich in einem anderen „Origin“ als das Frontend befindet.

## Origin { #origin }

# Behind a Proxy { #behind-a-proxy }

In many situations, you would use a **proxy** like Traefik or Nginx in front of your FastAPI app.

These proxies could handle HTTPS certificates and other things.

## Proxy Forwarded Headers { #proxy-forwarded-headers }