In fact, in some cases, it will even have **two JSON Schemas** in OpenAPI for the same Pydantic model, for input and output, depending on if they have **default values**.

Let's see how that works and how to change it if you need to do that.

## Pydantic Models for Input and Output { #pydantic-models-for-input-and-output }

Let's say you have a Pydantic model with default values, like this one:

<p>
A Go <i>program execution</i> is modeled as a set of goroutine executions,
together with a mapping <i>W</i> that specifies the write-like operation that each read-like operation reads from.
(Multiple executions of the same program can have different program executions.)
</p>

<p>
<b>Requirement 2</b>:
For a given program execution, the mapping <i>W</i>, when limited to synchronizing operations,

* The metrics APIs, `custom-metrics.metrics.k8s.io` and `metrics`, were moved from `v1alpha1` to `v1beta1`, and renamed to `custom.metrics.k8s.io` and `metrics.k8s.io`, respectively. If you have deployed a custom metrics adapter, ensure that it supports the new API version. If you have deployed Heapster in aggregated API server mode, upgrade Heapster to support the latest API version.

    },
    "user": {
        "username": "dave",
        "full_name": "Dave Grohl"
    }
}
```

/// note

Notice that even though the `item` was declared the same way as before, it is now expected to be inside of the body with a key `item`.

///

**FastAPI** will do the automatic conversion from the request, so that the parameter `item` receives its specific content and the same for `user`.

   *
   * <p>Thus, two graphs A and B are equal if <b>all</b> of the following are true:
   *
   * <ul>
   *   <li>A and B have equal {@link #isDirected() directedness}.
   *   <li>A and B have equal {@link #nodes() node sets}.
   *   <li>A and B have equal {@link #edges() edge sets}.
   * </ul>
   *
   * <p>Graph properties besides {@link #isDirected() directedness} do <b>not</b> affect equality.

   *
   * <p>Thus, two graphs A and B are equal if <b>all</b> of the following are true:
   *
   * <ul>
   *   <li>A and B have equal {@link #isDirected() directedness}.
   *   <li>A and B have equal {@link #nodes() node sets}.
   *   <li>A and B have equal {@link #edges() edge sets}.
   * </ul>
   *
   * <p>Graph properties besides {@link #isDirected() directedness} do <b>not</b> affect equality.

   *
   * <p>If a code point has no mapped replacement then it is checked against the safe range. If it
   * lies outside that, then {@link #escapeUnsafe} is called, otherwise no escaping is performed.
   *
   * @param replacementMap a map of characters to their escaped representations
   * @param safeMin the lowest character value in the safe range
   * @param safeMax the highest character value in the safe range

/// warning

Have in mind that as the Pydantic team no longer supports Pydantic v1 in recent versions of Python, starting from Python 3.14, using `pydantic.v1` is also not supported in Python 3.14 and above.

///

### Pydantic v1 and v2 on the same app { #pydantic-v1-and-v2-on-the-same-app }

   *
   * <p>Note, however, that although multiple locks can be created for a given Enum value, whether
   * it be through separate factory instances or through multiple calls to the same factory,
   * attempting to acquire multiple locks with the same Enum value (within the same thread) will
   * result in an IllegalStateException regardless of the factory's policy. For example:
   *
   * {@snippet :

     *       operations in a thread always happen-before subsequent read operations in the same
     *       thread
     *   <li>If this field's value == null because of unsafe publication, we know that it isn't the
     *       object associated with our thread, because if it was the publication wouldn't have been
     *       unsafe and we'd have seen our thread as the value. This state is also why a new