```

因为上述数据未包含已存储的属性 `"tax": 20.2`，新的输入模型会把 `"tax": 10.5` 作为默认值。

因此，本次操作把 `tax` 的值「更新」为 `10.5`。

## 用 `PATCH` 进行部分更新

<a href="https://developer.mozilla.org/zh-CN/docs/Web/HTTP/Methods/PATCH" class="external-link" target="_blank">HTTP `PATCH`</a> 操作用于更新 *部分* 数据。

即，只发送要更新的数据，其余数据保持不变。

/// note | 笔记

`PATCH` 没有 `PUT` 知名，也怎么不常用。

很多人甚至只用 `PUT` 实现部分更新。

**FastAPI** 对此没有任何限制，可以**随意**互换使用这两种操作。

    CountDownLatch latch = new CountDownLatch(1);
    Object unused =
        new Object() {
          @SuppressWarnings({"removal", "Finalize"}) // b/260137033
          @Override
          protected void finalize() {
            latch.countDown();
          }
        };
    unused = null; // Hint to the JIT that unused is unreachable
    GcFinalization.await(latch);
    assertEquals(0, latch.getCount());
  }

你可以在[发行说明](../release-notes.md){.internal-link target=_blank}中查看可用版本（例如查看当前最新版本）。

## 关于版本

遵循语义版本控制约定，任何低于`1.0.0`的版本都可能会添加 breaking changes。

FastAPI 还遵循这样的约定：任何`PATCH`版本更改都是为了bug修复和non-breaking changes。

/// tip

"PATCH"是最后一个数字，例如，在`0.2.3`中，PATCH版本是`3`。

///

因此，你应该能够固定到如下版本：

```txt
fastapi>=0.45.0,<0.46.0
```

"MINOR"版本中会添加breaking changes和新功能。

/// tip

             <b>fastapi run</b>

             Logs:

     <span style="background-color:#007166"><font color="#D3D7CF"> INFO </font></span>  Will watch for changes in these directories:
             <b>[</b><font color="#4E9A06">&apos;/home/user/code/awesomeapp&apos;</font><b>]</b>

             <b>fastapi run</b>

             Logs:

     <span style="background-color:#007166"><font color="#D3D7CF"> INFO </font></span>  Will watch for changes in these directories:
             <b>[</b><font color="#4E9A06">&apos;/home/user/code/awesomeapp&apos;</font><b>]</b>

 - The `batch/v2alpha1.CronJob` is deprecated in favor of `batch/v1beta1`.

 - The `batch/v2alpha1.ScheduledJob` was removed. Use `batch/v1beta1.CronJob` instead.

### Auth

 - The RBAC v1alpha1 API group is deprecated in favor of RBAC v1.

	// ErrInvalidValue invalid value
	ErrInvalidValue = errors.New("invalid value, should be pointer to struct or slice")
	// ErrInvalidValueOfLength invalid values do not match length
	ErrInvalidValueOfLength = errors.New("invalid association values, length doesn't match")
	// ErrPreloadNotAllowed preload is not allowed when count is used
	ErrPreloadNotAllowed = errors.New("preload is not allowed when count is used")

			erasureDisks[i] = nil
		}
		return erasureDisks
	}
	z.serverPools[0].erasureDisksMu.Unlock()

	t.Run("if-none-match with read quorum failure", func(t *testing.T) {
		// Test Case 1: if-none-match (create only if doesn't exist)
		// With if-none-match: *, this should only succeed if object doesn't exist.
		// Since read quorum fails, we can't determine if object exists.
		opts := ObjectOptions{

    val latch = CountDownLatch(1)
    webServer.enqueue(
      MockResponse
        .Builder()
        .webSocketUpgrade(
          object : WebSocketListener() {
            override fun onOpen(
              webSocket: WebSocket,
              response: Response,
            ) {
              try {
                latch.await() // The server can't respond to pings!

    with warnings.catch_warnings(record=True):
        warnings.simplefilter("always")
        monkeypatch.delattr("multipart.multipart.parse_options_header", raising=False)
    with pytest.raises(RuntimeError, match=multipart_incorrect_install_error):
        app = FastAPI()

        @app.post("/")
        async def root(username: str = Form()):
            return username  # pragma: nocover