from fastapi import FastAPI
from pydantic import BaseSettings


class Settings(BaseSettings):
    app_name: str = "Awesome API"
    admin_email: str
    items_per_user: int = 50


settings = Settings()
app = FastAPI()


@app.get("/info")
async def info():
    return {
        "app_name": settings.app_name,
        "admin_email": settings.admin_email,
        "items_per_user": settings.items_per_user,

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: CommonHeaders = Header()):

from datetime import datetime
from typing import Union

from fastapi import FastAPI
from fastapi.encoders import jsonable_encoder
from fastapi.responses import JSONResponse
from pydantic import BaseModel


class Item(BaseModel):
    title: str
    timestamp: datetime
    description: Union[str, None] = None


app = FastAPI()


@app.put("/items/{id}")
def update_item(id: str, item: Item):

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None

    class Config:
        schema_extra = {
            "examples": [
                {
                    "name": "Foo",
                    "description": "A very nice Item",
                    "price": 35.4,

from typing import Annotated, Literal

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

app = FastAPI()


class FilterParams(BaseModel):
    model_config = {"extra": "forbid"}

    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/")

from typing import Union

from fastapi import Body, FastAPI
from pydantic import BaseModel
from typing_extensions import Annotated

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None


@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Annotated[Item, Body(embed=True)]):

///

### 使用Pydantic中的`Required`代替省略号(`...`)

如果你觉得使用 `...` 不舒服，你也可以从 Pydantic 导入并使用 `Required`：

```Python hl_lines="2  8"
{!../../docs_src/query_params_str_validations/tutorial006d.py!}
```

/// tip

////

/// info

💡 🌖 🔃 <a href="https://docs.pydantic.dev/" class="external-link" target="_blank">Pydantic, ✅ 🚮 🩺</a>.

///

**FastAPI** 🌐 ⚓️ 🔛 Pydantic.

👆 🔜 👀 📚 🌅 🌐 👉 💡 [🔰 - 👩‍💻 🦮](tutorial/index.md){.internal-link target=_blank}.

/// tip

Se você quiser proteger sua API, há várias coisas melhores que você pode fazer, por exemplo:

* Certifique-se de ter modelos Pydantic bem definidos para seus corpos de solicitação e respostas.
* Configure quaisquer permissões e funções necessárias usando dependências.
* Nunca armazene senhas em texto simples, apenas hashes de senha.

                    "input": "b",
                },
            ]
        }
    ) | IsDict(
        # TODO: remove when deprecating Pydantic v1
        {
            "detail": [
                {
                    "loc": ["query", "needy"],
                    "msg": "field required",
                    "type": "value_error.missing",
                },