Also allowing to have multiple alternative security schemes that are then checked in a single dependency instead of each one verifying and returning the error to the client automatically when not satisfied. PR [#134](https://github.com/tiangolo/fastapi/pull/134).

* Update [SQL Tutorial](https://fastapi.tiangolo.com/tutorial/sql-databases/#create-a-middleware-to-handle-sessions) to close database sessions even when there are exceptions. PR [#89](https://github.com/tiangolo/fastapi/pull/89)...

And then, right after the `yield`, we unload the model. This code will be executed **after** the application **finishes handling requests**, right before the *shutdown*. This could, for example, release resources like memory or a GPU.

!!! tip
    The `shutdown` would happen when you are **stopping** the application.

name: str
```

Keep these in mind, so you don't get confused when using `=` and `:` with them.

### Create Pydantic *models* / schemas for reading / returning

Now create Pydantic *models* (schemas) that will be used when reading data, when returning it from the API.

For example, before creating an item, we don't know what will be the ID assigned to it, but when reading it (when returning it from the API) we will already know its ID.

Then, when you create an instance of that `Settings` class (in this case, in the `settings` object), Pydantic will read the environment variables in a case-insensitive way, so, an upper-case variable `APP_NAME` will still be read for the attribute `app_name`.

## 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:

```Python hl_lines="10-12"
{!../../../docs_src/response_cookies/tutorial001.py!}
```

!!! tip

    The original dependency could be used in a *path operation function*, a *path operation decorator* (when you don't use the return value), a `.include_router()` call, etc.

    FastAPI will still be able to override it.

Then you can reset your overrides (remove them) by setting `app.dependency_overrides` to be an empty `dict`:

```Python
app.dependency_overrides = {}
```

**FastAPI** has some default exception handlers.

These handlers are in charge of returning the default JSON responses when you `raise` an `HTTPException` and when the request has invalid data.

You can override these exception handlers with your own.

### Override request validation exceptions

When a request contains invalid data, **FastAPI** internally raises a `RequestValidationError`.

You can configure some extra <a href="https://swagger.io/docs/open-source-tools/swagger-ui/usage/configuration" class="external-link" target="_blank">Swagger UI parameters</a>.

To configure them, pass the `swagger_ui_parameters` argument when creating the `FastAPI()` app object or to the `get_swagger_ui_html()` function.

`swagger_ui_parameters` receives a dictionary with the configurations passed to Swagger UI directly.

## Context Managers

### What are "Context Managers"

# Separate OpenAPI Schemas for Input and Output or Not

When using **Pydantic v2**, the generated OpenAPI is a bit more exact and **correct** than before. 😎

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