That's why **FastAPI** is based on Starlette, as it is the fastest framework available (tested by third-party benchmarks).

### <a href="https://falconframework.org/" class="external-link" target="_blank">Falcon</a>

Falcon is another high performance Python framework, it is designed to be minimal, and work as the foundation of other frameworks like Hug.

    `OAuth2PasswordRequestForm` is that `OAuth2PasswordRequestFormStrict` requires the
    client to send the form field `grant_type` with the value `"password"`, which
    is required in the OAuth2 specification (it seems that for no particular reason),
    while for `OAuth2PasswordRequestForm` `grant_type` is optional.

    Read more about it in the

4. The `Author` dataclass is used as the `response_model` parameter.

5. You can use other standard type annotations with dataclasses as the request body.

    In this case, it's a list of `Item` dataclasses.

6. Here we are returning a dictionary that contains `items` which is a list of dataclasses.

    FastAPI is still capable of <abbr title="converting the data to a format that can be transmitted">serializing</abbr> the data to JSON.

def Path(  # noqa: N802
    default: Annotated[
        Any,
        Doc(
            """
            Default value if the parameter field is not set.

            This doesn't affect `Path` parameters as the value is always required.
            The parameter is available only for compatibility.
            """
        ),
    ] = ...,
    *,
    default_factory: Annotated[
        Union[Callable[[], Any], None],

The editor, mypy, and other tools won't complain about this because, in typing terms, `UserIn` is a subclass of `BaseUser`, which means it's a *valid* type when what is expected is anything that is a `BaseUser`.

### FastAPI Data Filtering

                request and send the client an error.

                If `auto_error` is set to `False`, when the HTTP Bearer token
                is not available, instead of erroring out, the dependency result will
                be `None`.

                This is useful when you want to have optional authentication.

                It is also useful when you want to have authentication that can be

# Generate Clients

As **FastAPI** is based on the OpenAPI specification, you get automatic compatibility with many tools, including the automatic API docs (provided by Swagger UI).

One particular advantage that is not necessarily obvious is that you can **generate clients** (sometimes called <abbr title="Software Development Kits">**SDKs**</abbr> ) for your API, for many different **programming languages**.

## OpenAPI Client Generators

    The information here is presented as a guideline, not a requirement.

    For example, when using GraphQL you normally perform all the actions using only `POST` operations.

### Step 4: define the **path operation function**

This is our "**path operation function**":

* **path**: is `/`.
* **operation**: is `get`.
* **function**: is the function below the "decorator" (below `@app.get("/")`).

# Cache for `create_cloned_field`
_CLONED_TYPES_CACHE: MutableMapping[
    Type[BaseModel], Type[BaseModel]
] = WeakKeyDictionary()


def is_body_allowed_for_status_code(status_code: Union[int, str, None]) -> bool:
    if status_code is None:
        return True
    # Ref: https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.1.0.md#patterned-fields-1
    if status_code in {
        "default",

    is_correct_username = secrets.compare_digest(
        current_username_bytes, correct_username_bytes
    )
    current_password_bytes = credentials.password.encode("utf8")
    correct_password_bytes = b"swordfish"
    is_correct_password = secrets.compare_digest(
        current_password_bytes, correct_password_bytes
    )
    if not (is_correct_username and is_correct_password):
        raise HTTPException(