assert response.json() == snapshot(
        {
            "detail": [
                {
                    "type": "missing",
                    "loc": ["cookie", "session_id"],
                    "msg": "Field required",
                    "input": {},
                }
            ]
        }
    )


def test_cookie_param_model_extra(client: TestClient):
    with client as c:

{* ../../docs_src/header_param_models/tutorial001_an_py310.py hl[9:14,18] *}

**FastAPI** will **extract** the data for **each field** from the **headers** in the request and give you the Pydantic model you defined.

## Check the Docs { #check-the-docs }

You can see the required headers in the docs UI at `/docs`:

<div class="screenshot">

    // - Class/Member Variables -/
    // --------------------------/

    /**
     * The ID of this phase, e.g., <code>generate-sources</code>.
     */
    private String id;

    /**
     * Field executions.
     */
    private java.util.List<Execution> executions;

    /**
     * Configuration to pass to all goals run in this phase.
     */
    private Object configuration;

    // -----------/

  @CanIgnoreReturnValue // to skip some bytes
  @Override
  double readDouble();

  @CanIgnoreReturnValue // to skip a line
  @Override
  @Nullable String readLine();

  @CanIgnoreReturnValue // to skip a field
  @Override
  String readUTF();

    assert response.status_code == 422
    assert response.json() == {
        "detail": [
            {
                "type": "missing",
                "loc": ["cookie", "session_id"],
                "msg": "Field required",
                "input": {},
            }
        ]
    }


def test_cookie_param_model_extra(client: TestClient):
    with client as c:
        c.cookies.set("session_id", "123")

{* ../../docs_src/query_param_models/tutorial001_an_py310.py hl[9:13,17] *}

**FastAPI** will **extract** the data for **each field** from the **query parameters** in the request and give you the Pydantic model you defined.

## Check the Docs { #check-the-docs }

You can see the query parameters in the docs UI at `/docs`:

<div class="screenshot">

@SuppressWarnings("JUnit4ClassUsedInJUnit3")
public class AbstractListTester<E extends @Nullable Object> extends AbstractCollectionTester<E> {
  /*
   * Previously we had a field named list that was initialized to the value of
   * collection in setUp(), but that caused problems when a tester changed the
   * value of list or collection but not both.
   */
  protected final List<E> getList() {

 
## Changes by Kind

### Deprecation

- Added a new `FileKeyRef` field to containers, allowing them to load variables from files by setting this field.
  

  }

  private static final class AvlNode<E extends @Nullable Object> {
    /*
     * For "normal" nodes, the type of this field is `E`, not `@Nullable E` (though note that E is a
     * type that can include null, as in a TreeMultiset<@Nullable String>).
     *
     * For the header node, though, this field contains `null`, regardless of the type of the
     * multiset.
     *