@app.post("/union")
        def endpoint(data: Union[dict, ModelV1A]):  # pragma: no cover
            return data


def test_raises_pydantic_v1_model_in_sequence() -> None:
    class ModelV1A(BaseModel):
        name: str

    app = FastAPI()

    with pytest.raises(PydanticV1NotSupportedError):

        @app.post("/sequence")
        def endpoint(data: list[ModelV1A]):  # pragma: no cover

    client = TestClient(app)
    with client.websocket_connect("/") as websocket:
        data = json.loads(websocket.receive_text())
        assert data == ["app", "index"]


def test_routerindex():
    client = TestClient(app)
    with client.websocket_connect("/router") as websocket:
        data = json.loads(websocket.receive_text())
        assert data == ["app", "router2", "router", "routerindex"]


def test_routerprefixindex():

	// - We use a KMS -> There must be non-empty key ID and a KMS data key.
	// - We use a K/V -> There must be no key ID and no KMS data key.
	// Otherwise, the caller has passed an invalid argument combination.
	if keyID == "" && len(kmsKey) != 0 {
		logger.CriticalIf(context.Background(), errors.New("The key ID must not be empty if a KMS data key is present"))
	}
	if keyID != "" && len(kmsKey) == 0 {

    assert state["context_a"] == "finished a"


def test_background_tasks():
    response = client.get("/context_b_bg")
    data = response.json()
    assert data["context_b"] == "started b"
    assert data["context_a"] == "started a"
    assert data["bg"] == "not set"
    middleware_state = json.loads(response.headers["x-state"])
    assert middleware_state["context_b"] == "started b"

    model_config = {"extra": "allow"}


@app.get("/query")
async def query_model_with_extra(data: Model = Query()):
    return data


@app.get("/header")
async def header_model_with_extra(data: Model = Header()):
    return data


@app.get("/cookie")
async def cookies_model_with_extra(data: Model = Cookie()):
    return data


def test_query_pass_extra_list():
    client = TestClient(app)
    resp = client.get(

 *               operations. May be null for top-level requests.
 * @param data Additional data associated with this request trace, typically containing the actual request
 *             object being processed or any application-specific state information. May be null if no
 *             additional data is needed.
 */
public record RequestTrace(
        @Nullable String context,

   * for the data format.
   */
  static <K extends @Nullable Object, V extends @Nullable Object> void populateMap(
      Map<K, V> map, ObjectInputStream stream, int size)
      throws IOException, ClassNotFoundException {
    for (int i = 0; i < size; i++) {
      @SuppressWarnings("unchecked") // reading data stored by writeMap
      K key = (K) stream.readObject();

	}
}

func TestCreateEmptySlice(t *testing.T) {
	data := []User{}
	if err := DB.Create(&data).Error; err != gorm.ErrEmptySlice {
		t.Errorf("no data should be created, got %v", err)
	}

	sliceMap := []map[string]interface{}{}
	if err := DB.Model(&User{}).Create(&sliceMap).Error; err != gorm.ErrEmptySlice {
		t.Errorf("no data should be created, got %v", err)
	}
}

And of course, it supports the same:

* data validation
* data serialization
* data documentation, etc.

This works the same way as with Pydantic models. And it is actually achieved in the same way underneath, using Pydantic.

/// info

///

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

The way HTML forms (`<form></form>`) sends the data to the server normally uses a "special" encoding for that data, it's different from JSON.

**FastAPI** will make sure to read that data from the right place instead of JSON.

/// note | Technical Details

Data from forms is normally encoded using the "media type" `application/x-www-form-urlencoded`.