* **Alembic**-Migrationen.
* **CORS** (Cross Origin Resource Sharing).
* **Celery**-Worker, welche Modelle und Code aus dem Rest des Backends selektiv importieren und verwenden können.

* Methods.
* Request payloads in the body, query parameters, etc.
* Response payloads.

You would also have **inline errors** for everything.

And whenever you update the backend code, and **regenerate** the frontend, it would have any new *path operations* available as methods, the old ones removed, and any other change would be reflected on the generated code. 🤓

import os
from typing import Any, Dict, List

from pdm.backend.hooks import Context

TIANGOLO_BUILD_PACKAGE = os.getenv("TIANGOLO_BUILD_PACKAGE", "fastapi")


def pdm_build_initialize(context: Context) -> None:
    metadata = context.config.metadata
    # Get custom config for the current package, from the env var
    config: Dict[str, Any] = context.config.data["tool"]["tiangolo"][
        "_internal-slim-build"

* To pass *headers*, use a `dict` in the `headers` parameter.
* For *cookies*, a `dict` in the `cookies` parameter.

For more information about how to pass data to the backend (using `httpx` or the `TestClient`) check the <a href="https://www.python-httpx.org" class="external-link" target="_blank">HTTPX documentation</a>.

!!! info

It was created to generate the HTML in the backend, not to create APIs used by a modern frontend (like React, Vue.js and Angular) or by other systems (like <abbr title="Internet of Things">IoT</abbr> devices) communicating with it.

<div class="termy">

```console
$ hypercorn main:app --worker-class trio
```

</div>

And that will start Hypercorn with your app using Trio as the backend.

Now you can use Trio internally in your app. Or even better, you can use AnyIO, to keep your code compatible with both Trio and asyncio. 🎉

## Deployment Concepts

您可以在[Project Generation - Template](https://fastapi.tiangolo.com/zh/project-generation/)的模板中找到一个 FastAPI 项目中的 Alembic 示例。具体在[`alembic`代码目录中](https://github.com/tiangolo/full-stack-fastapi-postgresql/tree/master/src/backend/app/alembic/)。

### 创建依赖项

现在使用我们在`sql_app/database.py`文件中创建的`SessionLocal`来创建依赖项。

我们需要每个请求有一个独立的数据库会话/连接（`SessionLocal`），在所有请求中使用相同的会话，然后在请求完成后关闭它。

然后将为下一个请求创建一个新会话。

[build-system]
requires = ["pdm-backend"]
build-backend = "pdm.backend"

[project]
name = "fastapi"
dynamic = ["version"]
description = "FastAPI framework, high performance, easy to learn, fast to code, ready for production"
readme = "README.md"
requires-python = ">=3.8"
authors = [
    { name = "Sebastián Ramírez", email = "******@****.***" },
]
classifiers = [
    "Intended Audience :: Information Technology",

# Security - First Steps

Let's imagine that you have your **backend** API in some domain.

And you have a **frontend** in another domain or in a different path of the same domain (or in a mobile application).

And you want to have a way for the frontend to authenticate with the backend, using a **username** and **password**.

We can use **OAuth2** to build that with **FastAPI**.

Und um über WebSockets mit Ihrem Backend zu kommunizieren, würden Sie wahrscheinlich die Werkzeuge Ihres Frontends verwenden.

Oder Sie verfügen möglicherweise über eine native Mobile-Anwendung, die direkt in nativem Code mit Ihrem WebSocket-Backend kommuniziert.

Oder Sie haben andere Möglichkeiten, mit dem WebSocket-Endpunkt zu kommunizieren.

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