from fastapi import FastAPI
from pydantic import BaseModel


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


app = FastAPI(separate_input_output_schemas=False)


@app.post("/items/")
def create_item(item: Item):
    return item


@app.get("/items/")
def read_items() -> list[Item]:
    return [
        Item(
            name="Portal Gun",

from fastapi import FastAPI

app = FastAPI()


@app.get("/users/{user_id}/items/{item_id}")
async def read_user_item(
    user_id: int, item_id: str, q: str | None = None, short: bool = False
):
    item = {"item_id": item_id, "owner_id": user_id}
    if q:
        item.update({"q": q})
    if not short:
        item.update(
            {"description": "This is an amazing item that has a long description"}
        )

from typing import Annotated, Union

from fastapi import Body, FastAPI
from pydantic import BaseModel

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)]):
    results = {"item_id": item_id, "item": item}

from typing import Union

from fastapi import Cookie, Depends, FastAPI

app = FastAPI()


def query_extractor(q: Union[str, None] = None):
    return q


def query_or_cookie_extractor(
    q: str = Depends(query_extractor),
    last_query: Union[str, None] = Cookie(default=None),
):
    if not q:
        return last_query
    return q


@app.get("/items/")

from typing import Annotated, Optional

from fastapi import FastAPI
from fastapi.testclient import TestClient
from pydantic import BaseModel, WithJsonSchema

app = FastAPI()


class Item(BaseModel):
    name: str

    description: Annotated[
        Optional[str], WithJsonSchema({"type": ["string", "null"]})
    ] = None

    model_config = {
        "json_schema_extra": {
            "x-something-internal": {"level": 4},

from fastapi import FastAPI, Path, Query

app = FastAPI()


@app.get("/items/{item_id}")
async def read_items(
    *,
    item_id: int = Path(title="The ID of the item to get", ge=0, le=1000),
    q: str,
    size: float = Query(gt=0, lt=10.5),
):
    results = {"item_id": item_id}
    if q:
        results.update({"q": q})
    if size:
        results.update({"size": size})

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 Annotated, Union

from fastapi import Depends, FastAPI

app = FastAPI()


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


@app.get("/items/")
async def read_items(commons: Annotated[dict, Depends(common_parameters)]):
    return commons


@app.get("/users/")

/// warning | 注意

你大概率不需要了解这些技术细节，可以跳过这一章节继续阅读后续的内容。

如果你使用的FastAPI的版本早于0.106.0，并且在使用后台任务中使用了包含 `yield` 的依赖项中的资源，那么这些细节会对你有一些用处。

///

### 包含 `yield` 和 `except` 的依赖项的技术细节

在FastAPI 0.110.0版本之前，如果使用了一个包含 `yield` 的依赖项，你在依赖项中使用 `except` 捕获了一个异常，但是你没有再次抛出该异常，这个异常会被自动抛出/转发到异常处理器或者内部服务错误处理器。

### 后台任务和使用 `yield` 的依赖项的技术细节

在FastAPI 0.106.0版本之前，在 `yield` 后面抛出异常是不可行的，因为 `yield` 之后的退出代码是在响应被发送之后再执行，这个时候异常处理器已经执行过了。

/// tip | Dica

Existe um gerador de projetos oficial com **FastAPI** e **PostgreSQL** incluindo um frontend e mais ferramentas: <a href="https://github.com/fastapi/full-stack-fastapi-template" class="external-link" target="_blank">https://github.com/fastapi/full-stack-fastapi-template</a>

///