У вас также может быть путь `/users/{user_id}`, чтобы получить данные о конкретном пользователе по его ID.

Поскольку *операции пути* выполняются в порядке их объявления, необходимо, чтобы путь для `/users/me` был объявлен раньше, чем путь для `/users/{user_id}`:


```Python hl_lines="6  11"
{!../../../docs_src/path_params/tutorial003.py!}
```

有时，*路径操作*中的路径是写死的。

比如要使用 `/users/me` 获取当前用户的数据。

然后还要使用 `/users/{user_id}`，通过用户 ID 获取指定用户的数据。

由于*路径操作*是按顺序依次运行的，因此，一定要在 `/users/{user_id}` 之前声明 `/users/me` ：

```Python hl_lines="6  11"
{!../../../docs_src/path_params/tutorial003.py!}
```

否则，`/users/{user_id}` 将匹配 `/users/me`，FastAPI 会**认为**正在接收值为 `"me"` 的 `user_id` 参数。

## 预设值

路径操作使用 Python 的 <abbr title="Enumeration">`Enum`</abbr> 类型接收预设的*路径参数*。

    assert response.json() == {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}


def test_query_params_str_validations_item_query_fixedquery(client: TestClient):
    response = client.get("/items/", params={"item-query": "fixedquery"})
    assert response.status_code == 200
    assert response.json() == {
        "items": [{"item_id": "Foo"}, {"item_id": "Bar"}],
        "q": "fixedquery",
    }

{!../../../docs_src/path_params/tutorial001.py!}
```

La valeur du paramètre `item_id` sera transmise à la fonction dans l'argument `item_id`.

Donc, si vous exécutez cet exemple et allez sur <a href="http://127.0.0.1:8000/items/foo" class="external-link" target="_blank">http://127.0.0.1:8000/items/foo</a>,
vous verrez comme réponse :

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

## Paramètres de chemin typés

                    "summary": "Read User Item",
                    "operationId": "read_user_item_items__item_id__get",
                    "parameters": [
                        {
                            "required": True,
                            "schema": {"title": "Item Id", "type": "string"},
                            "name": "item_id",
                            "in": "path",
                        },
                        {

In this case you will have to ensure that each operation ID is **unique** in some other way.

For example, you could make sure that each *path operation* has a tag, and then generate the operation ID based on the **tag** and the *path operation* **name** (the function name).

### Custom Generate Unique ID Function

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(
    q: Union[str, None] = Query(default=None, min_length=3, max_length=50),
):
    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[str | None, Query(min_length=3, max_length=50)] = None,
):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

app = FastAPI()


@app.get("/items/")
async def read_items(
    q: Annotated[Union[str, None], Query(min_length=3, max_length=50)] = None,
):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

            },
            "/items/{item_id}": {
                "get": {
                    "tags": ["items"],
                    "summary": "Read Item",
                    "operationId": "read_item_items__item_id__get",
                    "parameters": [
                        {
                            "required": True,
                            "schema": {"title": "Item Id", "type": "string"},