min_length: Annotated[
        Optional[int],
        Doc(
            """
            Minimum length for strings.
            """
        ),
    ] = None,
    max_length: Annotated[
        Optional[int],
        Doc(
            """
            Maximum length for strings.
            """
        ),
    ] = None,
    pattern: Annotated[
        Optional[str],
        Doc(

    ```

## Set-Typen

Aber dann denken wir darüber nach und stellen fest, dass sich die Tags nicht wiederholen sollen, es sollen eindeutige Strings sein.

Python hat einen Datentyp speziell für Mengen eindeutiger Dinge: das <abbr title="Menge">`set`</abbr>.

Deklarieren wir also `tags` als Set von Strings.

=== "Python 3.10+"

    ```Python hl_lines="12"
    {!> ../../../docs_src/body_nested_models/tutorial003_py310.py!}
    ```

    - **name**: each item must have a name
    - **description**: a long description
    - **price**: required
    - **tax**: if the item doesn't have tax, you can omit this
    - **tags**: a set of unique tag strings for this item
    """

# Path Parameters

You can declare path "parameters" or "variables" with the same syntax used by Python format strings:

```Python hl_lines="6-7"
{!../../../docs_src/path_params/tutorial001.py!}
```

The value of the path parameter `item_id` will be passed to your function as the argument `item_id`.

                                    "converted": {
                                        "summary": "An example with converted data",
                                        "description": "FastAPI can convert price `strings` to actual `numbers` automatically",
                                        "value": {"name": "Bar", "price": "35.4"},
                                    },
                                    "invalid": {

👆 💪 🛠️ ⚫️ 🙆 🎏 ☁ 💽 💖:

* **✳**
* **👸**
* **✳**
* **🇸🇲**
* **✳**, ♒️.

!!! tip

```

</div>

The response would be something like:

```JSON
{
    "message": "Hello World",
    "root_path": "/api/v1"
}
```

### Setting the `root_path` in the FastAPI app

Alternatively, if you don't have a way to provide a command line option like `--root-path` or equivalent, you can set the `root_path` parameter when creating your FastAPI app:

But you might want to still keep the return type annotation in the function to get the support from tools like editors and type checkers (e.g. mypy).

In this case, you can disable the response model generation by setting `response_model=None`:

=== "Python 3.10+"

    ```Python hl_lines="7"
    {!> ../../../docs_src/response_model/tutorial003_05_py310.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="9"

    response = client.post(
        "/admin/?token=jessica", headers={"X-Token": "fake-super-secret-token"}
    )
    assert response.status_code == 200, response.text
    assert response.json() == {"message": "Admin getting schwifty"}


def test_admin_invalid_header(client: TestClient):
    response = client.post("/admin/", headers={"X-Token": "invalid"})
    assert response.status_code == 400, response.text

    response = client.post(
        "/admin/?token=jessica", headers={"X-Token": "fake-super-secret-token"}
    )
    assert response.status_code == 200, response.text
    assert response.json() == {"message": "Admin getting schwifty"}


@needs_py39
def test_admin_invalid_header(client: TestClient):
    response = client.post("/admin/", headers={"X-Token": "invalid"})
    assert response.status_code == 400, response.text