# Body - Multiple Parameters

Now that we have seen how to use `Path` and `Query`, let's see more advanced uses of request body declarations.

## Mix `Path`, `Query` and body parameters

First, of course, you can mix `Path`, `Query` and request body parameter declarations freely and **FastAPI** will know what to do.

And you can also declare body parameters as optional, by setting the default to `None`:

//// tab | Python 3.10+

# Query Parameter Models

If you have a group of **query parameters** that are related, you can create a **Pydantic model** to declare them.

This would allow you to **re-use the model** in **multiple places** and also to declare validations and metadata for all the parameters at once. 😎

/// note

This is supported since FastAPI version `0.115.0`. 🤓

///

## Query Parameters with a Pydantic Model

{!> ../../docs_src/body/tutorial002_py310.py!}

## Request body + path parameters

You can declare path parameters and request body at the same time.

**FastAPI** will recognize that the function parameters that match path parameters should be **taken from the path**, and that function parameters that are declared to be Pydantic models should be **taken from the request body**.

{!> ../../docs_src/query_params/tutorial002.py!}
```

////

In this case, the function parameter `q` will be optional, and will be `None` by default.

/// check

Also notice that **FastAPI** is smart enough to notice that the path parameter `item_id` is a path parameter and `q` is not, so, it's a query parameter.

///

## Query parameter type conversion

You can also declare `bool` types, and they will be converted:

# Header Parameters

You can define Header parameters the same way you define `Query`, `Path` and `Cookie` parameters.

## Import `Header`

First import `Header`:

//// tab | Python 3.10+

```Python hl_lines="3"
{!> ../../docs_src/header_params/tutorial001_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="3"
{!> ../../docs_src/header_params/tutorial001_an_py39.py!}
```

////

# Path Parameters and Numeric Validations

In the same way that you can declare more validations and metadata for query parameters with `Query`, you can declare the same type of validations and metadata for path parameters with `Path`.

## Import Path

First, import `Path` from `fastapi`, and import `Annotated`:

//// tab | Python 3.10+

```Python hl_lines="1  3"
{!> ../../docs_src/path_params_numeric_validations/tutorial001_an_py310.py!}
```

   * parameters.
   */
  public MediaType withoutParameters() {
    return parameters.isEmpty() ? this : create(type, subtype);
  }

  /**
   * Replaces all parameters with the given parameters.
   *
   * @throws IllegalArgumentException if any parameter or value is invalid
   */

    ImmutableList<Parameter> parameters = delegate.getParameters();
    assertEquals(2, parameters.size());
    assertEquals(String.class, parameters.get(0).getType().getType());
    assertTrue(parameters.get(0).isAnnotationPresent(NotBlank.class));
    assertEquals(int.class, parameters.get(1).getType().getType());
    assertFalse(parameters.get(1).isAnnotationPresent(NotBlank.class));
    new EqualsTester()

    ImmutableList<Parameter> parameters = delegate.getParameters();
    assertEquals(2, parameters.size());
    assertEquals(String.class, parameters.get(0).getType().getType());
    assertTrue(parameters.get(0).isAnnotationPresent(NotBlank.class));
    assertEquals(int.class, parameters.get(1).getType().getType());
    assertFalse(parameters.get(1).isAnnotationPresent(NotBlank.class));
    new EqualsTester()

///

/// 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".

If you declare the type of your *path operation function* parameter as `bytes`, **FastAPI** will read the file for you and you will receive the contents as `bytes`.