被替换为了以下文本格式的错误信息：

```
1 validation error
path -> item_id
  value is not a valid integer (type=type_error.integer)

```

### `RequestValidationError` vs `ValidationError`

!!! warning "警告"

    如果您觉得现在还用不到以下技术细节，可以先跳过下面的内容。


`RequestValidationError` 是 Pydantic 的 <a href="https://docs.pydantic.dev/latest/concepts/models/#error-handling" class="external-link" target="_blank">`ValidationError`</a> 的子类。

```
1 validation error
path -> item_id
  value is not a valid integer (type=type_error.integer)
```

#### `RequestValidationError` 🆚 `ValidationError`

!!! warning
    👫 📡 ℹ 👈 👆 💪 🚶 🚥 ⚫️ 🚫 ⚠ 👆 🔜.

`RequestValidationError` 🎧-🎓 Pydantic <a href="https://docs.pydantic.dev/latest/concepts/models/#error-handling" class="external-link" target="_blank">`ValidationError`</a>.

以下のようなテキスト版を取得します:

```
1 validation error
path -> item_id
  value is not a valid integer (type=type_error.integer)
```

#### `RequestValidationError`と`ValidationError`

!!! warning "注意"
    これらは今のあなたにとって重要でない場合は省略しても良い技術的な詳細です。

`RequestValidationError`はPydanticの<a href="https://docs.pydantic.dev/latest/concepts/models/#error-handling" class="external-link" target="_blank">`ValidationError`</a>のサブクラスです。

This also means that if something changed it will be **reflected** on the client code automatically. And if you **build** the client it will error out if you have any **mismatch** in the data used.

```JSON
{
  "detail": [
    {
      "type": "int_parsing",
      "loc": [
        "path",
        "item_id"
      ],
      "msg": "Input should be a valid integer, unable to parse string as an integer",
      "input": "foo",
      "url": "https://errors.pydantic.dev/2.1/v/int_parsing"
    }
  ]
}
```

│   └── test_main.py
```

Let's say that now the file `main.py` with your **FastAPI** app has some other **path operations**.

It has a `GET` operation that could return an error.

It has a `POST` operation that could return several errors.

Both *path operations* require an `X-Token` header.

=== "Python 3.10+"

    ```Python
    {!> ../../../docs_src/app_testing/app_b_an_py310/main.py!}
    ```

* **Veloce da programmare**: Velocizza il lavoro consentendo il rilascio di nuove funzionalità tra il 200% e il 300% più rapidamente. *
* **Meno bug**: Riduce di circa il 40% gli errori che commettono gli sviluppatori durante la scrittura del codice. *

You can also combine `dataclasses` with other type annotations to make nested data structures.

In some cases, you might still have to use Pydantic's version of `dataclasses`. For example, if you have errors with the automatically generated API documentation.

In that case, you can simply swap the standard `dataclasses` with `pydantic.dataclasses`, which is a drop-in replacement:

                    "schema": {
                        "$ref": "#/components/schemas/Item"
                    }
                }
            }
        },
        "422": {
            "description": "Validation Error",
            "content": {
                "application/json": {
                    "schema": {
                        "$ref": "#/components/schemas/HTTPValidationError"
                    }
                }

之后，所有处理逻辑都一样。

但因为改变了 `GzipRequest.body`，**FastAPI** 加载请求体时会自动解压。

## 在异常处理器中访问请求体

!!! tip "提示"

    为了解决同样的问题，在 `RequestValidationError` 的自定义处理器使用 `body`  （[处理错误](../tutorial/handling-errors.md#use-the-requestvalidationerror-body){.internal-link target=_blank}）可能会更容易。

    但本例仍然可行，而且本例展示了如何与内部组件进行交互。

同样也可以在异常处理器中访问请求体。

此时要做的只是处理 `try`/`except` 中的请求：

```Python hl_lines="13  15"