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


class Item(BaseModel):
    name: str


app = FastAPI()


@app.get("/items/stream-bare-async")
async def stream_bare_async() -> AsyncIterable:
    yield {"name": "foo"}


@app.get("/items/stream-bare-sync")
def stream_bare_sync() -> Iterable:
    yield {"name": "bar"}


client = TestClient(app)

class Session:
    def __init__(self) -> None:
        self.data = ["foo", "bar", "baz"]
        self.open = True

    def __iter__(self) -> Generator[str, None, None]:
        for item in self.data:
            if self.open:
                yield item
            else:
                raise ValueError("Session closed")


@contextmanager
def acquire_session() -> Generator[Session, None, None]:
    session = Session()
    try:

from fastapi import FastAPI, Path

app = FastAPI()


@app.get("/items/{item_id}")
async def read_items(q: str, item_id: int = Path(title="The ID of the item to get")):
    results = {"item_id": item_id}
    if q:
        results.update({"q": q})

            json.append("[");
            boolean first = true;
            for (final Object item : (Collection<?>) value) {
                if (!first) {
                    json.append(", ");
                }
                first = false;
                appendJsonValue(json, item);
            }
            json.append("]");
        } else if (value instanceof Map) {
            json.append("{");

                        <ol class="breadcrumb float-sm-right">
                            <li class="breadcrumb-item active"><la:link href="/admin/badword">
                                <la:message key="labels.bad_word_link_list"/>
                            </la:link></li>
                            <li class="breadcrumb-item active"><la:message
                                    key="labels.bad_word_link_upload"/></li>

Just standard **Python**.

For example, for an `int`:

```Python
item_id: int
```

or for a more complex `Item` model:

```Python
item: Item
```

...and with that single declaration you get:

* Editor support, including:
    * Completion.
    * Type checks.
* Validation of data:

使用与声明路径和查询参数相同的方式，把它添加至*路径操作*：

{* ../../docs_src/body/tutorial001_py310.py hl[16] *}

...并把其类型声明为你创建的模型 `Item`。

## 结果 { #results }

仅使用这些 Python 类型声明，**FastAPI** 就可以：

* 以 JSON 形式读取请求体。
* （在必要时）把请求体转换为对应的类型。
* 校验数据。
    * 数据无效时返回清晰的错误信息，并指出错误数据的确切位置和内容。
* 把接收的数据赋值给参数 `item`。
    * 因为你把函数中的参数类型声明为 `Item`，所以还能获得所有属性及其类型的编辑器支持（补全等）。
* 为你的模型生成 [JSON Schema](https://json-schema.org) 定义，如果对你的项目有意义，还可以在其他地方使用它们。

from typing import Annotated

from fastapi import FastAPI, Path

app = FastAPI()


@app.get("/items/{item_id}")
async def read_items(
    item_id: Annotated[int, Path(title="The ID of the item to get", ge=1)], q: str
):
    results = {"item_id": item_id}
    if q:
        results.update({"q": q})

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(
    q: str | None = Query(
        default=None,
        alias="item-query",
        title="Query string",
        description="Query string for the items to search in the database that have a good match",
        min_length=3,
        max_length=50,
        pattern="^fixedquery$",
        deprecated=True,
    ),
):

            final List<StorageItem> items = client.listObjects(prefix, fessConfig.getStorageMaxItemsInPageAsInteger());

            for (final StorageItem item : items) {
                final Map<String, Object> map = new HashMap<>();
                map.put("id", item.getEncodedId());
                map.put("path", item.getPath());
                map.put("name", item.getName());