build-all.

    Takes an optional LANG argument with the name of the language to serve, by default
    en.
    """
    # Enable line numbers during local development to make it easier to highlight
    os.environ["LINENUMS"] = "true"
    if lang is None:
        lang = "en"
    lang_path: Path = docs_path / lang
    os.chdir(lang_path)
    mkdocs.commands.serve.serve(dev_addr="127.0.0.1:8008")

* If you translate pages, add a single pull request per page translated. That will make it much easier for others to review it.

        By asking questions in a structured way (following this) it will be much easier to help you.

        And there's a high chance that you will find the solution along the way and you won't even have to submit it and wait for an answer. 😎

    But as it's a common use case, it is provided by **FastAPI** directly, just to make it easier.

### Use the form data

!!! tip

### Other forms of asynchronous code

This style of using `async` and `await` is relatively new in the language.

But it makes working with asynchronous code a lot easier.

This same syntax (or almost identical) was also included recently in modern versions of JavaScript (in Browser and NodeJS).

But before that, handling asynchronous code was quite more complex and difficult.

Then you could want to have **a single container** with a **process manager** starting **several worker processes** inside.

#### Prometheus and Other Reasons

You could also have **other reasons** that would make it easier to have a **single container** with **multiple processes** instead of having **multiple containers** with **a single process** in each of them.

With **FastAPI**, using OpenAPI, you can define the names of these webhooks, the types of HTTP operations that your app can send (e.g. `POST`, `PUT`, etc.) and the request **bodies** that your app would send.

This can make it a lot easier for your users to **implement their APIs** to receive your **webhook** requests, they might even be able to autogenerate some of their own API code.

!!! info

## Créer une Issue

Vous pouvez <a href="https://github.com/tiangolo/fastapi/issues/new/choose" class="external-link" target="_blank">créer une Issue</a> dans le dépôt GitHub, par exemple pour :

* Poser une question ou s'informer sur un problème.
* Suggérer une nouvelle fonctionnalité.

**Note** : si vous créez un problème, alors je vais vous demander d'aider aussi les autres. 😉

## Créer une Pull Request

## Accessing the request body in an exception handler

!!! tip
    To solve this same problem, it's probably a lot easier to use the `body` in a custom handler for `RequestValidationError` ([Handling Errors](../tutorial/handling-errors.md#use-the-requestvalidationerror-body){.internal-link target=_blank}).

Of course, there are some cases where there's no problem in running the previous steps multiple times, in that case, it's a lot easier to handle.

!!! tip
    Also, keep in mind that depending on your setup, in some cases you **might not even need any previous steps** before starting your application.