callbacks.RegisterDefaultCallbacks(db, &callbacks.Config{
		CreateClauses:        []string{"INSERT", "VALUES", "ON CONFLICT", "RETURNING"},
		UpdateClauses:        []string{"UPDATE", "SET", "WHERE", "RETURNING"},
		DeleteClauses:        []string{"DELETE", "FROM", "WHERE", "RETURNING"},
		LastInsertIDReversed: true,
	})

	return nil
}

func (DummyDialector) DefaultValueOf(field *schema.Field) clause.Expression {

In this example, the function `generate_html_response()` already generates and returns a `Response` instead of returning the HTML in a `str`.

By returning the result of calling `generate_html_response()`, you are already returning a `Response` that will override the default **FastAPI** behavior.

                errors << "From non-null returning to null returning breaking change"
            } else if (oldNullability == Nullability.NON_NULL && newNullability == Nullability.UNMARKED) {
                errors << "From non-null returning to null-unmarked returning breaking change"
            } else if (oldNullability == Nullability.UNMARKED && newNullability == Nullability.NULLABLE) {

		// means either actually 0, or unknown. The only way
		// to explicitly say that the ContentLength is zero is
		// to set the Body to nil. But turns out too much code
		// depends on NewRequest returning a non-nil Body,
		// so we use a well-known ReadCloser variable instead
		// and have the http package also treat that sentinel
		// variable to mean explicitly zero.
		if req.GetBody != nil && req.ContentLength == 0 {

              }
            },
            directExecutor()));
    thingToCancel[0] = serializer.submit(Callables.returning(null), directExecutor());
    results.add(thingToCancel[0]);
    // Enqueue more than enough tasks to force reentrancy.
    for (int i = 0; i < 5; i++) {
      results.add(serializer.submit(Callables.returning(null), directExecutor()));
    }

    manualExecutorTask[0].run();

FastAPI will use this return type to:

* **Validate** the returned data.
    * If the data is invalid (e.g. you are missing a field), it means that *your* app code is broken, not returning what it should, and it will return a server error instead of returning incorrect data. This way you and your clients can be certain that they will receive the data and the data shape expected.
* Add a **JSON Schema** for the response, in the OpenAPI *path operation*.

You can add middleware to **FastAPI** applications.

A "middleware" is a function that works with every **request** before it is processed by any specific *path operation*. And also with every **response** before returning it.

* It takes each **request** that comes to your application.
* It can then do something to that **request** or run any needed code.

        mockNotifications.add(fileNotifyInfo1);
        mockNotifications.add(fileNotifyInfo2);
        mockNotifications.add(fileNotifyInfo3);
    }

    /**
     * Test watch() method returning notifications
     */
    @Test
    void testWatch() throws CIFSException {
        // Setup mock behavior
        when(watchHandle.watch()).thenReturn(mockNotifications);

        // Execute

You can also declare the `Response` parameter in dependencies, and set cookies (and headers) in them.

## Return a `Response` directly { #return-a-response-directly }

You can also create cookies when returning a `Response` directly in your code.

To do that, you can create a response as described in [Return a Response Directly](response-directly.md){.internal-link target=_blank}.

Then set Cookies in it, and then return it:

	}

	// mariadb with returning, values will be appended with id map
	if len(values) == beforeLen*2 {
		t.Skipf("This test case skipped, because the db supports returning")
	}

	for i := range values {
		v, ok := values[i]["id"]
		if !ok {
			t.Fatal("failed to create data from map with table, returning map has no primary key")
		}

		var result User