from typing import Union

from fastapi import FastAPI, Query
from typing_extensions import Annotated

app = FastAPI()


@app.get("/items/")
async def read_items(
    q: Annotated[Union[str, None], Query(title="Query string", min_length=3)] = None,
):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(
    q: Annotated[
        Union[str, None],
        Query(
            title="Query string",
            description="Query string for the items to search in the database that have a good match",
            min_length=3,
        ),
    ] = None,
):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:

constraints.Future.message      = {item} doit être dans le futur.
constraints.Max.message         = {item} doit être plus petit ou égal à {value}.
constraints.Min.message         = {item} doit être plus grand ou égal à {value}.
constraints.NotNull.message     = {item} ne peut pas être null.
constraints.Null.message        = {item} doit être null.
constraints.Past.message        = {item} doit être dans le passé.

例えば、４つのAPIエンドポイント（*path operations*）があるとします:

* `/items/public/`
* `/items/private/`
* `/users/{user_id}/activate`
* `/items/pro/`

そして、依存関係とサブ依存関係だけで、それぞれに異なるパーミッション要件を追加することができます:

```mermaid
graph TB

current_user(["current_user"])
active_user(["active_user"])
admin_user(["admin_user"])
paying_user(["paying_user"])

public["/items/public/"]
private["/items/private/"]

For example, let's say that you want to have a *path operation* that allows to update items, and returns HTTP status codes of 200 "OK" when successful.

But you also want it to accept new items. And when the items didn't exist before, it creates them, and returns an HTTP status code of 201 "Created".

        "paths": {
            "/items/": {
                "get": {
                    "responses": {
                        "200": {
                            "description": "Successful Response",
                            "content": {"application/json": {"schema": {}}},
                        }
                    },
                    "summary": "Read Items",

message ClusterRoleBindingList {
  // Standard object's metadata.
  // +optional
  optional k8s.io.apimachinery.pkg.apis.meta.v1.ListMeta metadata = 1;

  // Items is a list of ClusterRoleBindings
  repeated ClusterRoleBinding items = 2;
}

// ClusterRoleList is a collection of ClusterRoles.
// Deprecated in v1.17 in favor of rbac.authorization.k8s.io/v1 ClusterRoles, and will no longer be served in v1.22.

    try {
      equalsTester.testEquals();
    } catch (AssertionFailedError e) {
      assertErrorMessage(
          e,
          equalObject1
              + " [group 1, item 1] must be Object#equals to "
              + notEqualObject1
              + " [group 1, item 2]");
      return;
    }
    fail("Should get not equal to equal object error");
  }

  /**

http://www.example.com/
http://www.example.com/catalog?item=12&desc=vacation_hawaii
http://www.example.com/catalog?item=73&desc=vacation_new_zealand
http://www.example.com/catalog?item=74&desc=vacation_newfoundland

```

O valor do parâmetro que foi passado à `item_id` será passado para a sua função como o argumento `item_id`.

Então, se você rodar este exemplo e for até <a href="http://127.0.0.1:8000/items/foo" class="external-link" target="_blank">http://127.0.0.1:8000/items/foo</a>, você verá a seguinte resposta:

```JSON
{"item_id":"foo"}
```

## Parâmetros da rota com tipos