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: Annotated[int, Path(title="The ID of the item to get", ge=0, le=1000)],
    q: Union[str, None] = None,
    item: Union[Item, None] = None,
):

---

回到前面的代码示例，**FastAPI** 将会：

* 校验 `GET` 和 `PUT` 请求的路径中是否含有 `item_id`。
* 校验 `GET` 和 `PUT` 请求中的 `item_id` 是否为 `int` 类型。
    * 如果不是，客户端将会收到清晰有用的错误信息。
* 检查 `GET` 请求中是否有命名为 `q` 的可选查询参数（比如 `http://127.0.0.1:8000/items/foo?q=somequery`）。
    * 因为 `q` 被声明为 `= None`，所以它是可选的。
    * 如果没有 `None` 它将会是必需的 (如 `PUT` 例子中的请求体)。
* 对于访问 `/items/{item_id}` 的 `PUT` 请求，将请求体读取为 JSON 并：
    * 检查是否有必需属性 `name` 并且值为 `str` 类型 。

import inspect

from fastapi import APIRouter, FastAPI

method_names = ["get", "put", "post", "delete", "options", "head", "patch", "trace"]


def test_signatures_consistency():
    base_sig = inspect.signature(APIRouter.get)
    for method_name in method_names:
        router_method = getattr(APIRouter, method_name)
        app_method = getattr(FastAPI, method_name)
        router_sig = inspect.signature(router_method)

              Object value = new Object();
              result.put(key, value);
            }
            result.put(extraKey, extraValue);
            result.put(extraValue, null);
            return result;
          }
        };
    LoadingCache<Object, Object> cache = CacheBuilder.newBuilder().build(loader);
    cache.asMap().put(extraKey, extraKey);

            Metadata metadata = it.next();
            if (metadata instanceof PluginsMetadata pluginsMetadata) {
                it.remove();
                processedPlugins.put(pluginsMetadata.getGroupId(), pluginsMetadata);
            }
        }
    }

    @Override
    public Collection<? extends Metadata> prepare(Collection<? extends Artifact> artifacts) {

#### List { #list }

For example, let's define a variable to be a `list` of `str`.

Declare the variable, with the same colon (`:`) syntax.

As the type, put `list`.

As the list is a type that contains some internal types, you put them in square brackets:

{* ../../docs_src/python_types/tutorial006_py39.py hl[1] *}

/// info

Those internal types in the square brackets are called "type parameters".

  @Override
  public boolean containsValue(@Nullable Object value) {
    return inverse.containsKey(value);
  }

  // Modification Operations

  @CanIgnoreReturnValue
  @Override
  public @Nullable V put(@ParametricNullness K key, @ParametricNullness V value) {
    return putInBothMaps(key, value, false);
  }

  @CanIgnoreReturnValue
  @Override

                    descriptors.putIfAbsent(key, clone(desc));
                }
            }
        }
        return clone(desc);
    }

    @Override
    public void put(Key cacheKey, PluginDescriptor pluginDescriptor) {
        descriptors.put(cacheKey, clone(pluginDescriptor));
    }

    protected static PluginDescriptor clone(PluginDescriptor original) {
        return new PluginDescriptor(original);
    }

   * @throws UnsupportedOperationException always
   */
  @CanIgnoreReturnValue
  @Deprecated
  @Override
  @DoNotCall("Always throws UnsupportedOperationException")
  public @Nullable B put(TypeToken<? extends @NonNull B> key, @ParametricNullness B value) {
    throw new UnsupportedOperationException("Please use putInstance() instead.");
  }

  /**
   * Not supported. Use {@link #putInstance} instead.
   *

                            {
                                String key = getSnapshotVersionKey( sv );
                                versions.put( key, sv );
                            }
                            // never convert from legacy format
                            if ( !versions.isEmpty() )
                            {