# Response - Change Status Code { #response-change-status-code }

You probably read before that you can set a default [Response Status Code](../tutorial/response-status-code.md){.internal-link target=_blank}.

But in some cases you need to return a different status code than the default.

## Use case { #use-case }

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

@app.post("/invoices/", callbacks=invoices_callback_router.routes)
def create_invoice(invoice: Invoice, callback_url: HttpUrl | None = None):
    """
    Create an invoice.

    This will (let's imagine) let the API user (some external developer) create an
    invoice.

    And this path operation will:

    * Send the invoice to the client.
    * Collect the money from the client.

                }
                script {
                    name = "CLEAN_M2"
                    executionMode = BuildStep.ExecutionMode.ALWAYS
                    scriptContent = checkCleanDirUnixLike("%teamcity.agent.jvm.user.home%/.m2/.develocity", exitOnFailure = false)
                }
            }
        },

All disks online
-----------------
- All Unformatted - format all and return success.
- Some Unformatted - format all and return success.
- Any JBOD inconsistent - return failure
- Some are corrupt (missing format.json) - return failure
- Any unrecognized disks - return failure

Some disks are offline and we have quorum.
-----------------
- Some unformatted - format all and return success,
  treat disks offline as corrupted.

 *
 * <p>While it is recommended that service lifecycles be managed via this class, state transitions
 * initiated via other mechanisms do not impact the correctness of its methods. For example, if the
 * services are started by some mechanism besides {@link #startAsync}, the listeners will be invoked
 * when appropriate and {@link #awaitHealthy} will still work as expected.
 *

 *
 * <p>While it is recommended that service lifecycles be managed via this class, state transitions
 * initiated via other mechanisms do not impact the correctness of its methods. For example, if the
 * services are started by some mechanism besides {@link #startAsync}, the listeners will be invoked
 * when appropriate and {@link #awaitHealthy} will still work as expected.
 *

          </excludePackageNames>
          <!-- Ignore some tags that are found in Java 11 sources but not recognized... under -source 8, I think it was? I can no longer reproduce the failure. -->
          <tags>
            <tag>
              <name>apiNote</name>

* <a href="https://developers.liblab.com/tutorials/sdk-for-fastapi?utm_source=fastapi" class="external-link" target="_blank">liblab</a>

Some of these solutions may also be open source or offer free tiers, so you can try them without a financial commitment. Other commercial SDK generators are available and can be found online. 🤓

            )
        }
    }

    @Test
    fun `should fail if some method was upgraded but it was not actually changed`() {
        checkBinaryCompatibleFailsWithoutReport(
            v1 = {
                withJavaFile(
                    "java/com/example/Task.java",

# JSON Compatible Encoder { #json-compatible-encoder }

There are some cases where you might need to convert a data type (like a Pydantic model) to something compatible with JSON (like a `dict`, `list`, etc).

For example, if you need to store it in a database.

For that, **FastAPI** provides a `jsonable_encoder()` function.

## Using the `jsonable_encoder` { #using-the-jsonable-encoder }