from ._compat import PYDANTIC_V2, PYDANTIC_VERSION, Undefined

_Unset: Any = Undefined


class ParamTypes(Enum):
    query = "query"
    header = "header"
    path = "path"
    cookie = "cookie"


class Param(FieldInfo):
    in_: ParamTypes

    def __init__(
        self,
        default: Any = Undefined,
        *,
        default_factory: Union[Callable[[], Any], None] = _Unset,

        Required as Required,  # noqa: F401
    )
    from pydantic.fields import (  # type: ignore[no-redef,attr-defined]
        Undefined as Undefined,
    )
    from pydantic.fields import (  # type: ignore[no-redef, attr-defined]
        UndefinedType as UndefinedType,  # noqa: F401
    )
    from pydantic.schema import (
        field_schema,

from typing import Any, Dict, List, Optional, Sequence, Set, Tuple, Type, Union, cast

from fastapi import routing
from fastapi._compat import (
    GenerateJsonSchema,
    JsonSchemaValue,
    ModelField,
    Undefined,
    get_compat_model_name_map,
    get_definitions,
    get_schema_from_model_field,
    lenient_issubclass,
)
from fastapi.datastructures import DefaultPlaceholder
from fastapi.dependencies.models import Dependant

    Tuple,
    Type,
    Union,
    cast,
)

import anyio
from fastapi import params
from fastapi._compat import (
    PYDANTIC_V2,
    ErrorWrapper,
    ModelField,
    Required,
    Undefined,
    _regenerate_error_with_loc,
    copy_field_info,
    create_body_model,
    evaluate_forwardref,
    field_annotation_is_scalar,
    get_annotation_from_field_info,
    get_missing_field_error,

You will also get autocompletion for the payload to send:

<img src="/img/tutorial/generate-clients/image03.png">

!!! tip
    Notice the autocompletion for `name` and `price`, that was defined in the FastAPI application, in the `Item` model.

You will have inline errors for the data that you send:

<img src="/img/tutorial/generate-clients/image04.png">

The response object will also have autocompletion:

### Check the docs UI

But here's the fun part. ✨

The "official" way to access the app would be through the proxy with the path prefix that we defined. So, as we would expect, if you try the docs UI served by Uvicorn directly, without the path prefix in the URL, it won't work, because it expects to be accessed through the proxy.

        self.scope_str: Annotated[
            str,
            Doc(
                """
                All the scopes required by all the dependencies in a single string
                separated by spaces, as defined in the OAuth2 specification.
                """
            ),

    * This will be used by the **automatic docs**.
    * It will also be used by automatic client code generation tools.

But most importantly:

* It will **limit and filter** the output data to what is defined in the return type.
    * This is particularly important for **security**, we'll see more of that below.

## `response_model` Parameter

As an example, let's take this function:

```Python hl_lines="1  4"
{!../../../docs_src/python_types/tutorial009c.py!}
```

The parameter `name` is defined as `Optional[str]`, but it is **not optional**, you cannot call the function without the parameter:

```Python
say_hi()  # Oh, no, this throws an error! 😱
```

    return burgers
```

### More technical details

You might have noticed that `await` can only be used inside of functions defined with `async def`.

But at the same time, functions defined with `async def` have to be "awaited". So, functions with `async def` can only be called inside of functions defined with `async def` too.

So, about the egg and the chicken, how do you call the first `async` function?