import pytest
from fastapi import FastAPI
from fastapi.exceptions import FastAPIError


class NonPydanticModel:
    pass


def test_invalid_response_model_raises():
    with pytest.raises(FastAPIError):
        app = FastAPI()

        @app.get("/", response_model=NonPydanticModel)
        def read_root():
            pass  # pragma: nocover


def test_invalid_response_model_sub_type_raises():
    with pytest.raises(FastAPIError):

            pass  # pragma: nocover

    with pytest.raises(
        AssertionError,
        match=(
            "`Query` default value cannot be set in `Annotated` for 'item_id'. Set the"
            " default value with `=` instead."
        ),
    ):

        @app.get("/")
        async def get(item_id: Annotated[int, Query(default=1)]):
            pass  # pragma: nocover

# Configure Swagger UI

You can configure some extra <a href="https://swagger.io/docs/open-source-tools/swagger-ui/usage/configuration" class="external-link" target="_blank">Swagger UI parameters</a>.

To configure them, pass the `swagger_ui_parameters` argument when creating the `FastAPI()` app object or to the `get_swagger_ui_html()` function.

`swagger_ui_parameters` receives a dictionary with the configurations passed to Swagger UI directly.

from typing import List, Union

from pydantic import BaseModel


class ItemBase(BaseModel):
    title: str
    description: Union[str, None] = None


class ItemCreate(ItemBase):
    pass


class Item(ItemBase):
    id: int
    owner_id: int

    class Config:
        orm_mode = True


class UserBase(BaseModel):
    email: str


class UserCreate(UserBase):
    password: str

from typing import Annotated

from fastapi import Depends, FastAPI, HTTPException

app = FastAPI()


class InternalError(Exception):
    pass


def get_username():
    try:
        yield "Rick"
    except InternalError:
        print("Oops, we didn't raise again, Britney 😱")


@app.get("/items/{item_id}")
def get_item(item_id: str, username: Annotated[str, Depends(get_username)]):
    if item_id == "portal-gun":

        def serialize_dt_field(self, dt):
            return dt.replace(microsecond=0, tzinfo=timezone.utc).isoformat()

    class ModelWithCustomEncoderSubclass(ModelWithCustomEncoder):
        pass

    model = ModelWithCustomEncoder(dt_field=datetime(2019, 1, 1, 8))
    assert jsonable_encoder(model) == {"dt_field": "2019-01-01T08:00:00+00:00"}

In our code example above, we don't use it directly, but we pass it to FastAPI for it to use it.

The `lifespan` parameter of the `FastAPI` app takes an **async context manager**, so we can pass our new `lifespan` async context manager to it.

```Python hl_lines="22"
{!../../../docs_src/events/tutorial003.py!}
```

```

### Include the custom docs

Now you can create the *path operations* for the custom docs.

You can re-use FastAPI's internal functions to create the HTML pages for the docs, and pass them the needed arguments:

* `openapi_url`: the URL where the HTML page for the docs can get the OpenAPI schema for your API. You can use here the attribute `app.openapi_url`.
* `title`: the title of your API.

```JSON
{
  "detail": "Item not found"
}
```

!!! tip
    When raising an `HTTPException`, you can pass any value that can be converted to JSON as the parameter `detail`, not only `str`.

    You could pass a `dict`, a `list`, etc.

    They are handled automatically by **FastAPI** and converted to JSON.

## Add custom headers

* Create a `templates` object that you can re-use later.
* Declare a `Request` parameter in the *path operation* that will return a template.
* Use the `templates` you created to render and return a `TemplateResponse`, pass the name of the template, the request object, and a "context" dictionary with key-value pairs to be used inside of the Jinja2 template.

```Python hl_lines="4  11  15-18"
{!../../../docs_src/templates/tutorial001.py!}
```