Sie schreiben Standard-Python mit Typen:

```Python
from typing import List, Dict
from datetime import date

from pydantic import BaseModel

# Deklarieren Sie eine Variable als ein `str`
# und bekommen Sie Editor-Unterstütung innerhalb der Funktion
def main(user_id: str):

from datetime import datetime, timedelta, timezone
from typing import Annotated

from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from jose import JWTError, jwt
from passlib.context import CryptContext
from pydantic import BaseModel

# to get a string like this run:
# openssl rand -hex 32
SECRET_KEY = "09d25e094faa6ca2556c818166b7a9563b93f7099f6f0f4caa6cf63b88e8d3e7"

Чтобы достичь этого, первым делом нам нужно импортировать:

* `Query` из пакета `fastapi`:
* `Annotated` из пакета `typing` (или из `typing_extensions` для Python ниже 3.9)

=== "Python 3.10+"

    В Python 3.9 или выше, `Annotated` является частью стандартной библиотеки, таким образом вы можете импортировать его из `typing`.

    ```Python hl_lines="1  3"
    {!> ../../../docs_src/query_params_str_validations/tutorial002_an_py310.py!}

```console
$ pip install "uvicorn[standard]"

---> 100%
```

</div>

## Példa

### Hozd létre

* Hozz létre a `main.py` fájlt a következő tartalommal:

```Python
from typing import Union

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")

```console
$ pip install "uvicorn[standard]"

---> 100%
```

</div>

## Ejemplo

### Créalo

* Crea un archivo `main.py` con:

```Python
from fastapi import FastAPI
from typing import Union

app = FastAPI()


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: Union[str, None] = None):

### `Query` und `Annotated` importieren

Importieren Sie zuerst:

* `Query` von `fastapi`
* `Annotated` von `typing` (oder von `typing_extensions` in Python unter 3.9)

=== "Python 3.10+"

    In Python 3.9 oder darüber, ist `Annotated` Teil der Standardbibliothek, also können Sie es von `typing` importieren.

    ```Python hl_lines="1  3"
    {!> ../../../docs_src/query_params_str_validations/tutorial002_an_py310.py!}

from typing import Optional

from dirty_equals import IsDict
from fastapi import Depends, FastAPI, Security
from fastapi.security import OAuth2, OAuth2PasswordRequestFormStrict
from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()

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

<div class="termy">

```console
$ pip install "uvicorn[standard]"

---> 100%
```

</div>

## উদাহরণ

### তৈরি

- `main.py` নামে একটি ফাইল তৈরি করুন:

```Python
from typing import Union

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")

* Path `prefix`: `/items`.
* `tags`: (just one tag: `items`).
* Extra `responses`.
* `dependencies`: they all need that `X-Token` dependency we created.

So, instead of adding all that to each *path operation*, we can add it to the `APIRouter`.

```Python hl_lines="5-10  16  21" title="app/routers/items.py"
{!../../../docs_src/bigger_applications/app/routers/items.py!}
```

        * Processing a response after being generated by *path operation functions* but before returning it. E.g. adding custom headers, logging, adding extra metadata.
    * New docs section: [Custom Request and APIRoute class](https://fastapi.tiangolo.com/advanced/custom-request-and-route/).