from typing import Annotated

from fastapi import FastAPI, Header
from pydantic import BaseModel

app = FastAPI()


class CommonHeaders(BaseModel):
    host: str
    save_data: bool
    if_modified_since: str | None = None
    traceparent: str | None = None
    x_tag: list[str] = []


@app.get("/items/")
async def read_items(
    headers: Annotated[CommonHeaders, Header(convert_underscores=False)],
):

from typing import Annotated

import pytest
from fastapi import FastAPI, File, UploadFile
from fastapi.testclient import TestClient

from .utils import get_body_model_name

app = FastAPI()

# =====================================================================================
# Without aliases


@app.post("/optional-bytes", operation_id="optional_bytes")
async def read_optional_bytes(p: Annotated[bytes | None, File()] = None):

from typing import Annotated

import pytest
from fastapi import FastAPI, Query
from fastapi.testclient import TestClient
from inline_snapshot import snapshot
from pydantic import BaseModel, Field

app = FastAPI()

# =====================================================================================
# Without aliases


@app.get("/optional-list-str")
async def read_optional_list_str(
    p: Annotated[list[str] | None, Query()] = None,

from typing import Annotated, Literal

from fastapi import FastAPI, Query
from pydantic import BaseModel, Field

app = FastAPI()


class FilterParams(BaseModel):
    limit: int = Field(100, gt=0, le=100)
    offset: int = Field(0, ge=0)
    order_by: Literal["created_at", "updated_at"] = "created_at"
    tags: list[str] = []


@app.get("/items/")
async def read_items(filter_query: Annotated[FilterParams, Query()]):

from typing import Annotated, Any

from fastapi import FastAPI, Security
from fastapi.security import SecurityScopes
from fastapi.testclient import TestClient


async def security1(scopes: SecurityScopes):
    return scopes.scopes


async def security2(scopes: SecurityScopes):
    return scopes.scopes


async def dep3(
    dep1: Annotated[list[str], Security(security1, scopes=["scope1"])],

我们打算添加约束：即使 `q` 是可选的，但只要提供了该参数，**其长度不能超过 50 个字符**。

### 导入 `Query` 和 `Annotated` { #import-query-and-annotated }

为此，先导入：

- 从 `fastapi` 导入 `Query`
- 从 `typing` 导入 `Annotated`

{* ../../docs_src/query_params_str_validations/tutorial002_an_py310.py hl[1,3] *}

/// info | 信息

FastAPI 在 0.95.0 版本中添加了对 `Annotated` 的支持（并开始推荐使用）。

如果你的版本更旧，使用 `Annotated` 会报错。

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


@pytest.fixture(name="call_counter")
def call_counter_fixture():
    return {"count": 0}


@pytest.fixture(name="app")
def app_fixture(call_counter: dict[str, int]):
    def get_db():
        call_counter["count"] += 1
        return f"db_{call_counter['count']}"

        )
    return user


async def get_current_active_user(
    current_user: Annotated[User, Depends(get_current_user)],
):
    if current_user.disabled:
        raise HTTPException(status_code=400, detail="Inactive user")
    return current_user


@app.post("/token")
async def login(form_data: Annotated[OAuth2PasswordRequestForm, Depends()]):
    user_dict = fake_users_db.get(form_data.username)

from typing import Annotated

from fastapi import Depends, FastAPI

app = FastAPI()


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


CommonsDep = Annotated[dict, Depends(common_parameters)]


@app.get("/items/")
async def read_items(commons: CommonsDep):
    return commons


@app.get("/users/")

from typing import Annotated

from fastapi import FastAPI, File, UploadFile

app = FastAPI()


@app.post("/files/")
async def create_file(file: Annotated[bytes | None, File()] = None):
    if not file:
        return {"message": "No file sent"}
    else:
        return {"file_size": len(file)}


@app.post("/uploadfile/")
async def create_upload_file(file: UploadFile | None = None):
    if not file: