formField

final Route route = route(
  formField("color", color ->
    complete("The color is '" + color + "'")
  ),
  formField(StringUnmarshallers.INTEGER, "id", id ->
    complete("The id is '" + id + "'")
  )
);

// tests:
final FormData formData = FormData.create(Pair.create("color", "blue"));
testRoute(route).run(HttpRequest.POST("/").withEntity(formData.toEntity()))
  .assertEntity("The color is 'blue'");

testRoute(route).run(HttpRequest.GET("/"))
  .assertStatusCode(StatusCodes.BAD_REQUEST)
  .assertEntity("Request is missing required form field 'color'");