/// info

`Form` is a class that inherits directly from `Body`.

///

/// tip

To declare form bodies, you need to use `Form` explicitly, because without it the parameters would be interpreted as query parameters or body (JSON) parameters.

///

## About "Form Fields" { #about-form-fields }

You can write <a href="https://en.wikipedia.org/wiki/Markdown" class="external-link" target="_blank">Markdown</a> in the docstring, it will be interpreted and displayed correctly (taking into account docstring indentation).

{* ../../docs_src/path_operation_configuration/tutorial004_py310.py hl[17:25] *}

It will be used in the interactive docs:

* If the parameter is of a **singular type** (like `int`, `float`, `str`, `bool`, etc) it will be interpreted as a **query** parameter.
* If the parameter is declared to be of the type of a **Pydantic model**, it will be interpreted as a request **body**.

/// note

FastAPI will know that the value of `q` is not required because of the default value `= None`.

///

/// info

To declare headers, you need to use `Header`, because otherwise the parameters would be interpreted as query parameters.

///

## Automatic conversion { #automatic-conversion }

`Header` has a little extra functionality on top of what `Path`, `Query` and `Cookie` provide.

///

/// tip

To declare File bodies, you need to use `File`, because otherwise the parameters would be interpreted as query parameters or body (JSON) parameters.

///

The files will be uploaded as "form data".

     * The prefix before the {@code :} character, if present and longer than 1 character, is the syntax.
     * If no syntax is specified, or if its length is 1 character (interpreted as a Windows drive),
     * the default is a Maven-specific variation of the {@code "glob"} pattern.
     *
     * <p>The default implementation returns an empty list, which means to apply a language-dependent pattern.

## Multiple body params and query { #multiple-body-params-and-query }

Of course, you can also declare additional query parameters whenever you need, additional to any body parameters.

As, by default, singular values are interpreted as query parameters, you don't have to explicitly add a `Query`, you can just do:

```Python
q: Union[str, None] = None
```

Or in Python 3.10 and above:

```Python
q: str | None = None
```

die() {
  printf %s\\n "$1" >&2
  exit 1
}

trim() {
  # MWRAPPER-139:
  #   Trims trailing and leading whitespace, carriage returns, tabs, and linefeeds.
  #   Needed for removing poorly interpreted newline sequences when running in more
  #   exotic environments such as mingw bash on Windows.
  printf "%s" "${1}" | tr -d '[:space:]'
}

{
  "q": [
    "foo",
    "bar"
  ]
}
```

/// tip

To declare a query parameter with a type of `list`, like in the example above, you need to explicitly use `Query`, otherwise it would be interpreted as a request body.

///

The interactive API docs will update accordingly, to allow multiple values:

<img src="/img/tutorial/query-params-str-validations/image02.png">

      System.arraycopy(hash, 0, hashes, i * hashBytes, hash.length);
    }

    // Then hash the result array
    byte[] result = hashFunction.hash(hashes, 0);

    // interpreted in little-endian order.
    int verification = Integer.reverseBytes(Ints.fromByteArray(result));

    if (expected != verification) {
      throw new AssertionError(
          "Expected: "