You declare the "shape" of the data as classes with attributes.

And each attribute has a type.

Then you create an instance of that class with some values and it will validate the values, convert them to the appropriate type (if that's the case) and give you an object with all the data.

from dirty_equals import IsDict
from fastapi import Body, Cookie, FastAPI, Header, Path, Query
from fastapi._compat import PYDANTIC_V2
from fastapi.testclient import TestClient
from pydantic import BaseModel, ConfigDict


def create_app():
    app = FastAPI()

    class Item(BaseModel):
        data: str

        if PYDANTIC_V2:
            model_config = ConfigDict(

### Deklarieren Sie einen *Pfad-Parameter*

Dann erstellen Sie einen *Pfad-Parameter*, der als Typ die gerade erstellte Enum-Klasse hat (`ModelName`):

```Python hl_lines="16"
{!../../../docs_src/path_params/tutorial005.py!}
```

### Testen Sie es in der API-Dokumentation

Weil die erlaubten Werte für den *Pfad-Parameter* nun vordefiniert sind, kann die interaktive Dokumentation sie als Auswahl-Drop-Down anzeigen:

    result = subprocess.run(["git", "commit", "-m", message], check=True)
    logging.info("Pushing branch")
    subprocess.run(["git", "push", "origin", branch_name], check=True)
    logging.info("Creating PR")
    pr = repo.create_pull(title=message, body=message, base="master", head=branch_name)
    logging.info(f"Created PR: {pr.number}")

---

Now that we know the difference between the terms **process** and **program**, let's continue talking about deployments.

## Running on Startup

                    },
                    "summary": "Create File",
                    "operationId": "create_file_files__post",
                    "requestBody": {
                        "content": {
                            "multipart/form-data": {
                                "schema": {
                                    "$ref": "#/components/schemas/Body_create_file_files__post"
                                }

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from pydantic import BaseModel

app = FastAPI()

reusable_oauth2 = OAuth2(
    flows={
        "password": {
            "tokenUrl": "token",
            "scopes": {"read:users": "Read the users", "write:users": "Create users"},
        }
    }
)


class User(BaseModel):
    username: str


# Here we use string annotations to test them
def get_current_user(oauth_header: "str" = Security(reusable_oauth2)):

## First Steps

Let's see a very simple example. It will be so simple that it is not very useful, for now.

But this way we can focus on how the **Dependency Injection** system works.

### Create a dependency, or "dependable"

Let's first focus on the dependency.

It is just a function that can take all the same parameters that a *path operation function* can take:

=== "Python 3.10+"

    !!! tip
        Prefer to use the `Annotated` version if possible.

    ```Python hl_lines="1"
    {!> ../../../docs_src/request_files/tutorial001.py!}
    ```

## Define `File` Parameters

Create file parameters the same way you would for `Body` or `Form`:

=== "Python 3.9+"

    ```Python hl_lines="9"
    {!> ../../../docs_src/request_files/tutorial001_an_py39.py!}
    ```

=== "Python 3.8+"