Dict,
    Iterable,
    Optional,
    Type,
    TypeVar,
    cast,
)

from fastapi._compat import (
    PYDANTIC_V2,
    CoreSchema,
    GetJsonSchemaHandler,
    JsonSchemaValue,
    with_info_plain_validator_function,
)
from starlette.datastructures import URL as URL  # noqa: F401
from starlette.datastructures import Address as Address  # noqa: F401
from starlette.datastructures import FormData as FormData  # noqa: F401

oauth2_scheme = OAuth2PasswordBearer(
    tokenUrl="token",
    scopes={"me": "Read information about the current user.", "items": "Read items."},
)

app = FastAPI()


def verify_password(plain_password, hashed_password):
    return pwd_context.verify(plain_password, hashed_password)


def get_password_hash(password):
    return pwd_context.hash(password)


def get_user(db, username: str):
    if username in db:

oauth2_scheme = OAuth2PasswordBearer(
    tokenUrl="token",
    scopes={"me": "Read information about the current user.", "items": "Read items."},
)

app = FastAPI()


def verify_password(plain_password, hashed_password):
    return pwd_context.verify(plain_password, hashed_password)


def get_password_hash(password):
    return pwd_context.hash(password)


def get_user(db, username: str):
    if username in db:

oauth2_scheme = OAuth2PasswordBearer(
    tokenUrl="token",
    scopes={"me": "Read information about the current user.", "items": "Read items."},
)

app = FastAPI()


def verify_password(plain_password, hashed_password):
    return pwd_context.verify(plain_password, hashed_password)


def get_password_hash(password):
    return pwd_context.hash(password)


def get_user(db, username: str):
    if username in db:

    try:
        from pydantic_core.core_schema import (
            with_info_plain_validator_function as with_info_plain_validator_function,
        )
    except ImportError:  # pragma: no cover
        from pydantic_core.core_schema import (
            general_plain_validator_function as with_info_plain_validator_function,  # noqa: F401
        )

    Required = PydanticUndefined

### Override the `HTTPException` error handler

The same way, you can override the `HTTPException` handler.

For example, you could want to return a plain text response instead of JSON for these errors:

```Python hl_lines="3-4  9-11  22"
{!../../../docs_src/handling_errors/tutorial004.py!}
```

!!! note "Technical Details"

app.include_router(
    router_b_override, prefix="/b", default_response_class=PlainTextResponse
)


client = TestClient(app)

orjson_type = "application/x-orjson"
text_type = "text/plain; charset=utf-8"
html_type = "text/html; charset=utf-8"
override_type = "application/x-override"


def test_app():
    with client:
        response = client.get("/")

{!../../../docs_src/path_operation_advanced_configuration/tutorial006.py!}
```

In this example, we didn't declare any Pydantic model. In fact, the request body is not even <abbr title="converted from some plain format, like bytes, into Python objects">parsed</abbr> as JSON, it is read directly as `bytes`, and the function `magic_data_reader()` would be in charge of parsing it in some way.

                </mxCell>
                <mxCell id="85" value="&lt;span style=&quot;font-family: &amp;#34;roboto&amp;#34; ; font-size: 24px&quot;&gt;Plain response from: someapp.example.com&lt;/span&gt;" style="shape=hexagon;perimeter=hexagonPerimeter2;whiteSpace=wrap;html=1;fixedSize=1;strokeColor=#9673a6;strokeWidth=3;fillColor=#e1d5e7;" parent="1" vertex="1">

                        </Array>
                    </mxGeometry>
                </mxCell>
                <mxCell id="85" value="&lt;span style=&quot;font-family: &amp;#34;roboto&amp;#34; ; font-size: 24px&quot;&gt;Plain response from: someapp.example.com&lt;/span&gt;" style="shape=hexagon;perimeter=hexagonPerimeter2;whiteSpace=wrap;html=1;fixedSize=1;strokeColor=#9673a6;strokeWidth=3;fillColor=#e1d5e7;" vertex="1" parent="1">