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

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

=== "Python 3.10+"

	// Offset and out size cannot be negative.
	if offset < 0 || length < 0 {
		return 0, errUnexpected
	}

	// Do we have enough blocks?
	if len(enBlocks) < dataBlocks {
		return 0, reedsolomon.ErrTooFewShards
	}

	// Do we have enough data?
	if int64(getDataBlockLen(enBlocks, dataBlocks)) < length {
		return 0, reedsolomon.ErrShortData
	}

	// Counter to decrement total left to write.

                "tearDownTwo should have been run before tearDownOne", false, tearDownOne.ran);
          }
        };

    final SimpleTearDown tearDownTwo = new SimpleTearDown(callback);
    stack.addTearDown(tearDownTwo);

    assertEquals(false, tearDownOne.ran);
    assertEquals(false, tearDownTwo.ran);

    stack.runTearDown();

    assertEquals("tearDownOne should have run", true, tearDownOne.ran);

<blockquote markdown="1">

**FastAPI** wouldn't exist if not for the previous work of others.

There have been many tools created before that have helped inspire its creation.

I have been avoiding the creation of a new framework for several years. First I tried to solve all the features covered by **FastAPI** using many different frameworks, plug-ins, and tools.

    * Simple `meshConfig` changes have been approved in the past. Functionality should not be enabled by default.
* For large API changes, 2 members of the TOC must approve the PR before release manager approval in the release branch
  of the istio/api repository. This does not have to wait for the weekly TOC meeting.
    * Risk should be assessed in the PR.
        * Have installs and upgrades affected by this feature?

!!! tip
    Notice the autocompletion for `name` and `price`, that was defined in the FastAPI application, in the `Item` model.

You will have inline errors for the data that you send:

<img src="/img/tutorial/generate-clients/image04.png">

The response object will also have autocompletion:

<img src="/img/tutorial/generate-clients/image05.png">

## FastAPI App with Tags

  /*
   * Ideally, this class would have exposed only constructors that require a non-null cause. See
   * https://github.com/jspecify/jspecify-reference-checker/blob/61aafa4ae52594830cfc2d61c8b113009dbdb045/src/main/java/com/google/jspecify/nullness/NullSpecTransfer.java#L789
   * and https://github.com/jspecify/jspecify/issues/490.
   *
   * (Perhaps it should also have required that its cause was a RuntimeException. However, that

* Maven test harness for plugin execution model
* Eclipse IDE tooling for plugin execution model and metadata model

- we also seem to have information like the plugin lifecycle model that's buried inside the maven execution model
- we also seem to have artifact information tangled inside the plugin model
- we have to deal with scripting implementations (groovy, beanshell, ruby)
- we need to deal with a shared context for plugins, like the guarded mojos

* **Uvicorn**:
    * Will have the best performance, as it doesn't have much extra code apart from the server itself.

```Python hl_lines="2"
@app.get('/')
def results():
    results = some_library()
    return results
```

---