"purple":      "#ab47bd",
        "deep-purple": "#7e56c2",
        "indigo":      "#4051b5",
        "blue":        "#2094f3",
        "light-blue":  "#02a6f2",
        "cyan":        "#00bdd6",
        "teal":        "#009485",
        "green":       "#4cae4f",
        "light-green": "#8bc34b",
        "lime":        "#cbdc38",
        "yellow":      "#ffec3d",
        "amber":       "#ffc105",
        "orange":      "#ffa724",

  palette:
  - media: '(prefers-color-scheme: light)'
    scheme: default
    primary: teal
    accent: amber
    toggle:
      icon: material/lightbulb
      name: Switch to dark mode
  - media: '(prefers-color-scheme: dark)'
    scheme: slate
    primary: teal
    accent: amber
    toggle:
      icon: material/lightbulb-outline
      name: Switch to light mode
  features:
  - search.suggest

---

## Install FastAPI

The first step is to install FastAPI.

For the tutorial, you might want to install it with all the optional dependencies and features:

<div class="termy">

```console
$ pip install "fastapi[all]"

---> 100%
```

</div>

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 benefit of raising an exception over `return`ing a value will be more evident in the section about Dependencies and Security.

## Do not Separate Schemas

Now, there are some cases where you might want to have the **same schema for input and output**.

Probably the main use case for this is if you already have some autogenerated client code/SDKs and you don't want to update all the autogenerated client code/SDKs yet, you probably will want to do it at some point, but maybe not right now.

```Python hl_lines="5-6"
{!../../../docs_src/dependencies/tutorial007.py!}
```

!!! tip
    You can use `async` or regular functions.

    **FastAPI** will do the right thing with each, the same as with normal dependencies.

## A dependency with `yield` and `try`

If you use a `try` block in a dependency with `yield`, you'll receive any exception that was thrown when using the dependency.

# Testing Dependencies with Overrides

## Overriding dependencies during testing

There are some scenarios where you might want to override a dependency during testing.

You don't want the original dependency to run (nor any of the sub-dependencies it might have).

<div style="text-align: right; margin-right: 10%;">Kevin Glisson, Marc Vilanova, Forest Monsen - <strong>Netflix</strong> <a href="https://netflixtechblog.com/introducing-dispatch-da4b8a2a8072" target="_blank"><small>(Ref)</small></a></div>

---

„_Ich bin überglücklich mit **FastAPI**. Es macht so viel Spaß!_“

<div style="text-align: right; margin-right: 10%;">Kabir Khan - <strong>Microsoft</strong> <a href="https://github.com/tiangolo/fastapi/pull/26" target="_blank"><small>(ref)</small></a></div>

---

"_We adopted the **FastAPI** library to spawn a **REST** server that can be queried to obtain **predictions**. [for Ludwig]_"