Without a data validation system, you would have to do all the checks by hand, in code.

These features are what Marshmallow was built to provide. It is a great library, and I have used it a lot before.

# External Links and Articles

**FastAPI** has a great community constantly growing.

There are many posts, articles, tools, and projects, related to **FastAPI**.

Here's an incomplete list of some of them.

!!! tip

        "/items/plumbus?token=jessica", headers={"X-Token": "fake-super-secret-token"}
    )
    assert response.status_code == 200, response.text
    assert response.json() == {"item_id": "plumbus", "name": "The great Plumbus"}


def test_put_forbidden(client: TestClient):
    response = client.put(
        "/items/bar?token=jessica", headers={"X-Token": "fake-super-secret-token"}
    )

        "/items/plumbus?token=jessica", headers={"X-Token": "fake-super-secret-token"}
    )
    assert response.status_code == 200, response.text
    assert response.json() == {"item_id": "plumbus", "name": "The great Plumbus"}


@needs_py39
def test_put_forbidden(client: TestClient):
    response = client.put(
        "/items/bar?token=jessica", headers={"X-Token": "fake-super-secret-token"}
    )

If you declare it as is, because it is a singular value, **FastAPI** will assume that it is a query parameter.

But you can instruct **FastAPI** to treat it as another body key using `Body`:

=== "Python 3.10+"

    ```Python hl_lines="23"
    {!> ../../../docs_src/body_multiple_params/tutorial003_an_py310.py!}
    ```

=== "Python 3.9+"

As part of that, I needed to investigate, test and use many alternatives.

The history of **FastAPI** is in great part the history of its predecessors.

As said in the section [Alternatives](alternatives.md){.internal-link target=_blank}:

<blockquote markdown="1">

**FastAPI** wouldn't exist if not for the previous work of others.

async def update_item(item_id: str):
    if item_id != "plumbus":
        raise HTTPException(
            status_code=403, detail="You can only update the item: plumbus"
        )

async def update_item(item_id: str):
    if item_id != "plumbus":
        raise HTTPException(
            status_code=403, detail="You can only update the item: plumbus"
        )

Up to now, you have been using common data types, like:

* `int`
* `float`
* `str`
* `bool`

But you can also use more complex data types.

And you will still have the same features as seen up to now:

* Great editor support.
* Data conversion from incoming requests.
* Data conversion for response data.
* Data validation.
* Automatic annotation and documentation.

## Other data types

        "/items/plumbus?token=jessica", headers={"X-Token": "fake-super-secret-token"}
    )
    assert response.status_code == 200, response.text
    assert response.json() == {"item_id": "plumbus", "name": "The great Plumbus"}


def test_put_forbidden(client: TestClient):
    response = client.put(
        "/items/bar?token=jessica", headers={"X-Token": "fake-super-secret-token"}
    )