# Middleware

You can add middleware to **FastAPI** applications.

A "middleware" is a function that works with every **request** before it is processed by any specific *path operation*. And also with every **response** before returning it.

* It takes each **request** that comes to your application.
* It can then do something to that **request** or run any needed code.

                                    "normal": {
                                        "summary": "A normal example",
                                        "description": "A **normal** item works correctly.",
                                        "value": {
                                            "name": "Foo",
                                            "description": "A very nice Item",

Um **die Grundlagen von HTTPS** aus Sicht des Benutzers zu erlernen, schauen Sie sich <a href="https://howhttps.works/" class="external-link" target="_blank">https://howhttps.works/</a> an.

Aus **Sicht des Entwicklers** sollten Sie beim Nachdenken über HTTPS Folgendes beachten:

* Für HTTPS muss **der Server** über von einem **Dritten** generierte **„Zertifikate“** verfügen.

And of course, it supports the same:

* data validation
* data serialization
* data documentation, etc.

This works the same way as with Pydantic models. And it is actually achieved in the same way underneath, using Pydantic.

!!! info
    Keep in mind that dataclasses can't do everything Pydantic models can do.

In this scenario, each one of the cleaners (including you) would be a processor, doing their part of the job.

### Preprocess the OpenAPI Specification for the Client Generator

The generated code still has some **duplicated information**.

We already know that this method is related to the **items** because that word is in the `ItemsService` (taken from the tag), but we still have the tag name prefixed in the method name too. 😕

We will probably still want to keep it for OpenAPI in general, as that will ensure that the operation IDs are **unique**.

    response = client.get("/cookie_example_examples/")
    assert response.status_code == 200, response.text


def test_openapi_schema():
    """
    Test that example overrides work:

    * pydantic model schema_extra is included
    * Body(example={}) overrides schema_extra in pydantic model
    * Body(examples{}) overrides Body(example={}) and schema_extra in pydantic model
    """

* In lines starting with `===` or `!!!`, translate only the ` "... Text ..."` part. Leave the rest unchanged.

* You can translate info boxes like `!!! warning` with for example `!!! warning "Achtung"`. But do not change the word immediately after the `!!!`, it determines the color of the info box.

* Do not change the paths in links to images, code files, Markdown documents.

    But keep in mind that, as everything is handled in memory, in a single list, it will only work while the process is running, and will only work with a single process.

      - uses: actions/checkout@v4
      # Ref: https://github.com/actions/runner/issues/2033
      - name: Fix git safe.directory in container
        run: mkdir -p /home/runner/work/_temp/_github_home && printf "[safe]\n\tdirectory = /github/workspace" > /home/runner/work/_temp/_github_home/.gitconfig
      # Allow debugging with tmate
      - name: Setup tmate session
        uses: mxschmitt/action-tmate@v3