```

!!! Note "笔记"

    注意，本例与数据库通信时使用 `await`，因此要把*路径操作函数*声明为异步函数（`asnyc`）。

### 关于 `{**note.dict(), "id": last_record_id}`

`note` 是 Pydantic `Note` 对象：

`note.dict()` 返回包含如下数据的**字典**：

```Python
{
    "text": "Some note",
    "completed": False,
}
```

但它不包含 `id` 字段。

因此要新建一个包含 `note.dict()` 键值对的**字典**：

```Python
{**note.dict()}
```

!!! note
    Notice that as we communicate with the database using `await`, the *path operation function* is declared with `async`.

### About `{**note.dict(), "id": last_record_id}`

`note` is a Pydantic `Note` object.

`note.dict()` returns a `dict` with its data, something like:

```Python
{
    "text": "Some note",
    "completed": False,
}
```

   * but not the other, the shorter iterable is considered to be less than the longer one. For
   * example, a lexicographical natural ordering over integers considers {@code [] < [1] < [1, 1] <
   * [1, 2] < [2]}.
   *
   * <p>Note that {@code ordering.lexicographical().reverse()} is not equivalent to {@code

   * natural ordering.
   *
   * <p><b>Note:</b> if mutability is not required, use {@link ImmutableSortedSet#copyOf(Iterable)}
   * instead.
   *
   * <p><b>Note:</b> If {@code elements} is a {@code SortedSet} with an explicit comparator, this
   * method has different behavior than {@link TreeSet#TreeSet(SortedSet)}, which returns a {@code
   * TreeSet} with that comparator.
   *

Então, ele usará o nome dos parâmetros como chaves (nome dos campos) no corpo, e espera um corpo como:

```JSON
{
    "item": {
        "name": "Foo",
        "description": "The pretender",
        "price": 42.0,
        "tax": 3.2
    },
    "user": {
        "username": "dave",
        "full_name": "Dave Grohl"
    }
}
```

!!! note "Nota"

participant dep as Dep with yield
participant operation as Path Operation
participant tasks as Background tasks

    Note over client,tasks: Can raise exception for dependency, handled after response is sent
    Note over client,operation: Can raise HTTPException and can change the response
    client ->> dep: Start request
    Note over dep: Run code up to yield
    opt raise
        dep -->> handler: Raise HTTPException

{
    "name": "Barz",
    "price": 3,
    "description": None,
}
```

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。

participant dep as Dep with yield
participant operation as Path Operation
participant tasks as Background tasks

    Note over client,tasks: Can raise exception for dependency, handled after response is sent
    Note over client,operation: Can raise HTTPException and can change the response
    client ->> dep: Start request
    Note over dep: Run code up to yield
    opt raise
        dep -->> handler: Raise HTTPException

   *
   * <p>Note that {@code function} must be consistent according to {@code this} equivalence
   * relation. That is, invoking {@link Function#apply} multiple times for a given value must return
   * equivalent results. For example, {@code
   * Equivalence.identity().onResultOf(Functions.toStringFunction())} is broken because it's not

   *
   * <p>Note that {@code function} must be consistent according to {@code this} equivalence
   * relation. That is, invoking {@link Function#apply} multiple times for a given value must return
   * equivalent results. For example, {@code
   * Equivalence.identity().onResultOf(Functions.toStringFunction())} is broken because it's not