}

  @Override
  public @Nullable Object[] toArray() {
    return standardToArray();
  }

  @Override
  @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
  public <T extends @Nullable Object> T[] toArray(T[] array) {
    return standardToArray(array);
  }

  @Override
  public String toString() {
    return entrySet().toString();
  }

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 { #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`:

          Object[] result = standardToArray();
          return result;
        }

        @Override
        @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
        public <T extends @Nullable Object> T[] toArray(T[] array) {
          return standardToArray(array);
        }
      };
    }

You can use the same type declarations with `str`, `float`, `bool` and many other complex data types.

Several of these are explored in the next chapters of the tutorial.

## Order matters { #order-matters }

            } catch (ClassCastException e) {
              return false;
            }
          }

          @Override
          @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
          public <T extends @Nullable Object> T[] toArray(T[] array) {
            T[] result = super.toArray(array);
            if (size() < result.length) {

### Based on open standards { #based-on-open-standards }

* <a href="https://github.com/OAI/OpenAPI-Specification" class="external-link" target="_blank"><strong>OpenAPI</strong></a> for API creation, including declarations of <abbr title="also known as: endpoints, routes">path</abbr> <abbr title="also known as HTTP methods, as POST, GET, PUT, DELETE">operations</abbr>, parameters, request bodies, security, etc.

But you can re-order them, and have the value without a default (the query parameter `q`) first.

It doesn't matter for **FastAPI**. It will detect the parameters by their names, types and default declarations (`Query`, `Path`, etc), it doesn't care about the order.

So, you can declare your function as:

//// tab | Python 3.8 non-Annotated

/// tip

Prefer to use the `Annotated` version if possible.

///

We could do better.

We can declare a `UserBase` model that serves as a base for our other models. And then we can make subclasses of that model that inherit its attributes (type declarations, validation, etc).

All the data conversion, validation, documentation, etc. will still work as normally.

          Object[] result = standardToArray();
          return result;
        }

        @Override
        @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
        public <T extends @Nullable Object> T[] toArray(T[] array) {
          return standardToArray(array);
        }
      };
    }

Then I contributed to it, to make it fully compliant with JSON Schema, to support different ways to define constraint declarations, and to improve editor support (type checks, autocompletion) based on the tests in several editors.