settings: Settings,
    query: str,
    after: Union[str, None] = None,
    category_id: Union[str, None] = None,
) -> Dict[str, Any]:
    headers = {"Authorization": f"token {settings.input_token.get_secret_value()}"}
    # category_id is only used by one query, but GraphQL allows unused variables, so
    # keep it here for simplicity
    variables = {"after": after, "category_id": category_id}
    response = httpx.post(

```JSON
{
    "detail": [
        {
            "loc": [
                "query",
                "needy"
            ],
            "msg": "field required",
            "type": "value_error.missing"
        }
    ]
}
```

`needy` は必須のパラメータなので、URLにセットする必要があります:

```
http://127.0.0.1:8000/items/foo-item?needy=sooooneedy
```

...これはうまくいくでしょう:

```JSON
{

⤴️ 👆 💪 🤙 👈 🐍 📋:

<div class="termy">

```console
// Here we don't set the env var yet
$ python main.py

// As we didn't set the env var, we get the default value

Hello World from Python

// But if we create an environment variable first
$ export MY_NAME="Wade Wilson"

// And then call the program again
$ python main.py

// Now it can read the environment variable

!!! tip
    Note that, much like [dependencies in *path operation decorators*](dependencies/dependencies-in-path-operation-decorators.md){.internal-link target=_blank}, no value will be passed to your *path operation function*.

The end result is that the item paths are now:

* `/items/`
* `/items/{item_id}`

...as we intended.

So:

```Python
q: Union[str, None] = Query(default=None)
```

...makes the parameter optional, with a default value of `None`, the same as:

```Python

                    "loc": ["body", "file"],
                    "msg": "field required",
                    "type": "value_error.missing",
                },
                {
                    "loc": ["body", "fileb"],
                    "msg": "field required",
                    "type": "value_error.missing",
                },
                {
                    "loc": ["body", "token"],

                    "loc": ["body", "item"],
                    "msg": "field required",
                    "type": "value_error.missing",
                },
                {
                    "loc": ["body", "user"],
                    "msg": "field required",
                    "type": "value_error.missing",
                },
                {
                    "loc": ["body", "importance"],

    with pytest.raises(ResponseValidationError) as err:
        client.get("/model/modelX")
    assert err.value.errors() == [
        IsDict(
            {
                "type": "value_error",
                "loc": ("response", "name"),
                "msg": "Value error, name must end in A",
                "input": "modelX",
                "ctx": {"error": HasRepr("ValueError('name must end in A')")},

    * Add support for enumerations in *path operation* parameters. New documentation: [Path Parameters: Predefined values](https://fastapi.tiangolo.com/tutorial/path-params/#predefined-values).

):
    if security_scopes.scopes:
        authenticate_value = f'Bearer scope="{security_scopes.scope_str}"'
    else:
        authenticate_value = "Bearer"
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": authenticate_value},
    )
    try: