在FastAPI中仍然可以单独使用 `BackgroundTask`，但您必须在代码中创建对象，并返回包含它的Starlette `Response`。

更多细节查看 <a href="https://www.starlette.dev/background/" class="external-link" target="_blank">Starlette's official docs for Background Tasks</a>.

## 告诫

如果您需要执行繁重的后台计算，并且不一定需要由同一进程运行（例如，您不需要共享内存、变量等），那么使用其他更大的工具（如 <a href="https://docs.celeryq.dev" class="external-link" target="_blank">Celery</a>）可能更好。

	err := w.WriteHeader(&Header{
		Name: "lorem.txt",
		Mode: 0600,
		Size: int64(len(inp)),
	})
	if err != nil {
		f.Fatalf("failed to create writer: %s", err)
	}

///

Если у вас старое приложение FastAPI с Pydantic v1, здесь я покажу, как мигрировать на Pydantic v2, и **новые возможности в FastAPI 0.119.0**, которые помогут выполнить постепенную миграцию.

## Официальное руководство { #official-guide }

У Pydantic есть официальное <a href="https://docs.pydantic.dev/latest/migration/" class="external-link" target="_blank">руководство по миграции</a> с v1 на v2.

In the case of Spanish, the 2-letter code is `es`. So, the directory for Spanish translations is located at `docs/es/`.

/// tip

The main ("official") language is English, located at `docs/en/`.

///

Now run the live server for the docs in Spanish:

<div class="termy">

```console

> For a comprehensive overview, please visit the [official Gradle project homepage](https://gradle.org).

---

### 🚀 **Getting Started**

- Familiarity with AWS S3 API.
- Familiarity with Python and installing dependencies.

### 2. Install boto3

Install `aws-sdk-python` from AWS SDK for Python official docs [here](https://aws.amazon.com/sdk-for-python/)

### 3. Example

### Check the docs UI { #check-the-docs-ui }

But here's the fun part. ✨

They have proven to be **FastAPI Experts** by helping many others. ✨

/// tip

You could become an official FastAPI Expert too!

Just [help others with questions in GitHub](help-fastapi.md#help-others-with-questions-in-github){.internal-link target=_blank}. 🤓

///

You can see the **FastAPI Experts** for:

common:cuda_clang --config=cuda
common:cuda_clang --@local_config_cuda//:cuda_compiler=clang
common:cuda_clang --copt=-Qunused-arguments
# Select supported compute capabilities (supported graphics cards).
# This is the same as the official TensorFlow builds.
# See https://developer.nvidia.com/cuda-gpus#compute
# `compute_XY` enables PTX embedding in addition to SASS. PTX
# is forward compatible beyond the current compute capability major

Então, você pode usá-lo com:

{* ../../docs_src/path_params/tutorial004_py39.py hl[6] *}

/// tip | Dica
Você pode precisar que o parâmetro contenha `/home/johndoe/myfile.txt`, com uma barra inicial (`/`).

Nesse caso, a URL seria: `/files//home/johndoe/myfile.txt`, com uma barra dupla (`//`) entre `files` e `home`.
///

## Recapitulação { #recap }