from typing import Optional

from fastapi import Depends, FastAPI
from pydantic import BaseModel, validator

app = FastAPI()


class ModelB(BaseModel):
    username: str


class ModelC(ModelB):
    password: str


class ModelA(BaseModel):
    name: str
    description: Optional[str] = None
    model_b: ModelB

    @validator("name")
    def lower_username(cls, name: str, values):

from datetime import datetime, timedelta, timezone

import jwt
from fastapi import Depends, FastAPI, HTTPException, Security, status
from fastapi.security import (
    OAuth2PasswordBearer,
    OAuth2PasswordRequestForm,
    SecurityScopes,
)
from jwt.exceptions import InvalidTokenError
from passlib.context import CryptContext
from pydantic import BaseModel, ValidationError

# to get a string like this run:
# openssl rand -hex 32

    ```python
    from typing import Annotated

    from fastapi import Depends, FastAPI
    from fastapi.security import HTTPBasic, HTTPBasicCredentials

    app = FastAPI()

    security = HTTPBasic()


    @app.get("/users/me")
    def read_current_user(credentials: Annotated[HTTPBasicCredentials, Depends(security)]):
        return {"username": credentials.username, "password": credentials.password}

🎏 🌌 👆 ⚙️ `Body`, `Query`, ♒️. ⏮️ 👆 *➡ 🛠️ 🔢* 🔢, ⚙️ `Depends` ⏮️ 🆕 🔢:

//// tab | 🐍 3️⃣.6️⃣ & 🔛

```Python hl_lines="15  20"
{!> ../../docs_src/dependencies/tutorial001.py!}
```

////

//// tab | 🐍 3️⃣.1️⃣0️⃣ & 🔛

```Python hl_lines="11  16"
{!> ../../docs_src/dependencies/tutorial001_py310.py!}
```

////

👐 👆 ⚙️ `Depends` 🔢 👆 🔢 🎏 🌌 👆 ⚙️ `Body`, `Query`, ♒️, `Depends` 👷 👄 🎏.

from fastapi import APIRouter, Depends, HTTPException

from ..dependencies import get_token_header

router = APIRouter(
    prefix="/items",
    tags=["items"],
    dependencies=[Depends(get_token_header)],
    responses={404: {"description": "Not found"}},
)


fake_items_db = {"plumbus": {"name": "Plumbus"}, "gun": {"name": "Portal Gun"}}


@router.get("/")
async def read_items():
    return fake_items_db

//// tab | Python 3.8+

```Python hl_lines="1"
async def needy_dependency(fresh_value: Annotated[str, Depends(get_value, use_cache=False)]):
    return {"fresh_value": fresh_value}
```

////

//// tab | Python 3.8+ non-Annotated

/// tip | "Dica"

from fastapi import Depends, FastAPI
from fastapi.testclient import TestClient

app = FastAPI()


async def common_parameters(q: str | None = None, skip: int = 0, limit: int = 100):
    return {"q": q, "skip": skip, "limit": limit}


@app.get("/items/")
async def read_items(commons: dict = Depends(common_parameters)):
    return {"message": "Hello Items!", "params": commons}


@app.get("/users/")

from fastapi import Depends, FastAPI, Security
from fastapi.security import APIKeyHeader
from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()

api_key = APIKeyHeader(name="key")


class User(BaseModel):
    username: str


def get_current_user(oauth_header: str = Security(api_key)):
    user = User(username=oauth_header)
    return user


@app.get("/users/me")

from fastapi import Depends, FastAPI
from fastapi.testclient import TestClient

app = FastAPI()


async def user_exists(user_id: int):
    return True


@app.get("/users/{user_id}", dependencies=[Depends(user_exists)])
async def read_users(user_id: int):
    pass


client = TestClient(app)


def test_read_users():
    response = client.get("/users/42")
    assert response.status_code == 200, response.text

from fastapi import Depends, FastAPI, Security
from fastapi.security import APIKeyHeader
from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()

api_key = APIKeyHeader(name="key", description="An API Key Header")


class User(BaseModel):
    username: str


def get_current_user(oauth_header: str = Security(api_key)):
    user = User(username=oauth_header)
    return user