For example, imagine that you want to return an HTTP status code of "OK" `200` by default.

But if the data didn't exist, you want to create it, and return an HTTP status code of "CREATED" `201`.

But you still want to be able to filter and convert the data you return with a `response_model`.

For those cases, you can use a `Response` parameter.

## Use a `Response` parameter { #use-a-response-parameter }

Like `item.model_dump(exclude_unset=True)`.

/// info

In Pydantic v1 the method was called `.dict()`, it was deprecated (but still supported) in Pydantic v2, and renamed to `.model_dump()`.

The examples here use `.dict()` for compatibility with Pydantic v1, but you should use `.model_dump()` instead if you can use Pydantic v2.

///

            assertTrue(successfulThreads.get() > 0, "At least some threads should complete successfully");

            // The rate limiter should still be functional after concurrent access
            assertTrue(concurrentLimiter.checkAttempt("finaluser", "192.168.3.1"),
                    "Rate limiter should still be functional after concurrent operations");

            // Verify that the rate limiter tracked some activity

            // Refresh should not break anything
            orig.refresh();
            copy.refresh();

            // Both should still return null
            assertNull(orig.getSubject(), "Original should still return null after refresh");
            assertNull(copy.getSubject(), "Clone should still return null after refresh");
        }
    }

    @Test
    @DisplayName("renew: invokes getSubject and returns self")

   * response body is [closed][ResponseBody]. The recipient of the callback may consume the response
   * body on another thread.
   *
   * Note that transport-layer success (receiving a HTTP response code, headers and body) does not
   * necessarily indicate application-layer success: `response` may still indicate an unhappy HTTP
   * response code like 404 or 500.
   */

        auth.resetAuthenticationTimestamp();
        long afterReset = System.currentTimeMillis();

        // Should still not be expired
        assertFalse(auth.isExpired());

        // Wait for original TTL to pass
        Thread.sleep(600);

        // Should still not be expired because we reset
        assertFalse(auth.isExpired());

        // Wait for the full TTL since reset

    assertEquals(
        "next() should still return first element after peeking", "A", peekingIterator.next());

    assertEquals("Should be able to peek() at middle element", "B", peekingIterator.peek());
    assertEquals(
        "Should be able to peek() middle element multiple times", "B", peekingIterator.peek());
    assertEquals(
        "next() should still return middle element after peeking", "B", peekingIterator.next());

When you return a `Response` directly its data is not validated, converted (serialized), or documented automatically.

But you can still document it as described in [Additional Responses in OpenAPI](additional-responses.md){.internal-link target=_blank}.

/// warning

The current page still doesn't have a translation for this language.

But you can help translating it: [Contributing](https://fastapi.tiangolo.com/contributing/){.internal-link target=_blank}.

    endsFirst.start()
    endsFirst.join()
    // First response is still waiting.
    assertThat(firstResponseCode.get()).isEqualTo(0)
    // Second response is done.
    assertThat(secondResponseCode.get()).isEqualTo(200)
    latch.countDown()
    startsFirst.join()
    // And now it's done!
    assertThat(firstResponseCode.get()).isEqualTo(200)
    // (Still done).
    assertThat(secondResponseCode.get()).isEqualTo(200)
  }