<div class="termy">

```console
$ pip install "uvicorn[standard]"

---> 100%
```

</div>

## Exemple

### Créez

* Créez un fichier `main.py` avec :

```Python
from typing import Union

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
def read_root():

## OpenID Connect

OpenID Connect is another specification, based on **OAuth2**.

It just extends OAuth2 specifying some things that are relatively ambiguous in OAuth2, to try to make it more interoperable.

For example, Google login uses OpenID Connect (which underneath uses OAuth2).

But Facebook login doesn't support OpenID Connect. It has its own flavor of OAuth2.

### OpenID (not "OpenID Connect")

OpenID Connect é outra especificação, baseada em **OAuth2**.

Ela é apenas uma extensão do OAuth2 especificando algumas coisas que são relativamente ambíguas no OAuth2, para tentar torná-lo mais interoperável.

Por exemplo, o login do Google usa OpenID Connect (que por baixo dos panos usa OAuth2).

Mas o login do Facebook não tem suporte para OpenID Connect. Ele tem a própria implementação do OAuth2.

### OpenID (não "OpenID Connect")

<div class="termy">

```console
$ pip install "uvicorn[standard]"

---> 100%
```

</div>

## Example

### Create it

* Create a file `main.py` with:

```Python
from typing import Union

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
def read_root():

So you can come back and see exactly what you need.

## Run the code

All the code blocks can be copied and used directly (they are actually tested Python files).

To run any of the examples, copy the code to a file `main.py`, and start `uvicorn` with:

<div class="termy">

```console
$ uvicorn main:app --reload

## Exécuter le code

Tous les blocs de code peuvent être copiés et utilisés directement (il s'agit en fait de fichiers Python testés).

Pour exécuter l'un de ces exemples, copiez le code dans un fichier `main.py`, et commencez `uvicorn` avec :

<div class="termy">

```console
$ uvicorn main:app --reload

* Share database connections.
* Enforce security, authentication, role requirements, etc.
* And many other things...

All these, while minimizing code repetition.

## First Steps

Let's see a very simple example. It will be so simple that it is not very useful, for now.

But this way we can focus on how the **Dependency Injection** system works.

### Create a dependency, or "dependable"

Let's first focus on the dependency.

<div class="termy">

```console
$ pip install "uvicorn[standard]"

---> 100%
```

</div>

## Exemplo

### Crie

* Crie um arquivo `main.py` com:

```Python
from typing import Union

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
def read_root():