## Return Type and Data Filtering { #return-type-and-data-filtering }

Let's continue from the previous example. We wanted to **annotate the function with one type**, but we wanted to be able to return from the function something that actually includes **more data**.

We want FastAPI to keep **filtering** the data using the response model. So that even though the function returns more data, the response will only include the fields declared in the response model.

       changes with every test execution, such that running the test
       actually changes the test classpath itself. This means that it
       can"t benefit from incremental build acceleration, because on every
       execution it sees that the classpath has changed, and so to be
       safe, it needs to re-run.

       - This is unfortunate, because actually it would be safe to declare

# ----------------------------------------------------------
#                                                      Mail
#                                                     ------
# Does it send mock mail? (true: no send actually, logging only)
mail.send.mock = false

# SMTP server settings for main: host:port
mail.smtp.server.main.host.and.port = localhost:25

# The prefix of subject to show test environment or not

# ----------------------------------------------------------
#                                                      Mail
#                                                     ------
# Does it send mock mail? (true: no send actually, logging only)
mail.send.mock = false

# SMTP server settings for main: host:port
mail.smtp.server.main.host.and.port = localhost:25

# The prefix of subject to show test environment or not

 *
 * <p><b>Note:</b> The dispatcher is orthogonal to the subscriber's {@code Executor}. The dispatcher
 * controls the order in which events are dispatched, while the executor controls how (i.e. on which
 * thread) the subscriber is actually called when an event is dispatched to it.
 *
 * @author Colin Decker
 */
abstract class Dispatcher {

  /**
   * Returns a dispatcher that queues events that are posted reentrantly on a thread that is already

{* ../../docs_src/body_fields/tutorial001_an_py310.py hl[11:14] *}

`Field` works the same way as `Query`, `Path` and `Body`, it has all the same parameters, etc.

/// note | Technical Details

Actually, `Query`, `Path` and others you'll see next create objects of subclasses of a common `Param` class, which is itself a subclass of Pydantic's `FieldInfo` class.

And Pydantic's `Field` returns an instance of `FieldInfo` as well.

   *
   * <p>Note that, in cases where {@code sizeIfKnown} returns zero, it is <i>possible</i> that bytes
   * are actually available for reading. (For example, some special files may return a size of 0
   * despite actually having content when read.) This means that a source may return {@code true}
   * from {@code isEmpty()} despite having readable content.
   *

 *
 * @author Louis Wasserman
 */
public class OutsideEventBusTest extends TestCase {

  /*
   * If you do this test from common.eventbus.EventBusTest, it doesn't actually test the behavior.
   * That is, even if exactly the same method works from inside the common.eventbus package tests,
   * it can fail here.
   */
  public void testAnonymous() {

# ----------------------------------------------------------
#                                                      Mail
#                                                     ------
# Does it send mock mail? (true: no send actually, logging only)
mail.send.mock = false

# SMTP server settings for main: host:port
mail.smtp.server.main.host.and.port = localhost:25

# The prefix of subject to show test environment or not

   * Map#remove}, {@link ConcurrentMap#remove}, or {@link Iterator#remove}.
   */
  EXPLICIT {
    @Override
    boolean wasEvicted() {
      return false;
    }
  },

  /**
   * The entry itself was not actually removed, but its value was replaced by the user. This can
   * result from the user invoking {@link Cache#put}, {@link LoadingCache#refresh}, {@link Map#put},