# Request Parameters

Here's the reference information for the request parameters.

These are the special functions that you can put in *path operation function* parameters or dependency functions with `Annotated` to get data from the request.

It includes:

* `Query()`
* `Path()`
* `Body()`
* `Cookie()`
* `Header()`
* `Form()`
* `File()`

You can import them all directly from `fastapi`:

```python

  fun emptyCache(parameters: Pair<FileSystem, Boolean>) {
    setUp(parameters.first, parameters.second)
    cache.close()
    assertJournalEquals()
  }

  @ParameterizedTest
  @ArgumentsSource(FileSystemParamProvider::class)
  fun recoverFromInitializationFailure(parameters: Pair<FileSystem, Boolean>) {
    setUp(parameters.first, parameters.second)

    }

    public void test_convertParameterMap() {
        String parameters;
        Map<String, String> parameterMap;

        parameters = "";
        parameterMap = ParameterUtil.parse(parameters);
        assertEquals(0, parameterMap.size());

        parameters = "domain";
        parameterMap = ParameterUtil.parse(parameters);
        assertEquals(1, parameterMap.size());

# 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+

{!> ../../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**.

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

                "get": {
                    "tags": ["path1a", "path1b"],
                    "summary": "Path1 Override",
                    "operationId": "path1_override_override1_get",
                    "parameters": [
                        {
                            "required": True,
                            "schema": {"title": "Level1", "type": "string"},
                            "name": "level1",

        this.hostname = value;
    }

    public String getParameters() {
        checkSpecifiedProperty("parameters");
        return convertEmptyToNull(parameters);
    }

    public void setParameters(String value) {
        registerModifiedProperty("parameters");
        this.parameters = value;
    }

    public String getPassword() {
        checkSpecifiedProperty("password");

# Query Parameters

When you declare other function parameters that are not part of the path parameters, they are automatically interpreted as "query" parameters.

```Python hl_lines="9"
{!../../docs_src/query_params/tutorial001.py!}
```

The query is the set of key-value pairs that go after the `?` in a URL, separated by `&` characters.

For example, in the URL:

```
http://127.0.0.1:8000/items/?skip=0&limit=10
```

# 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!}
```

////