IDBCursor.update()

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规范
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update() 方法在 IDBCursor interface returns an IDBRequest object, and, in a separate thread, updates the value at the current position of the cursor in the object store. If the cursor points to a record that has just been deleted, a new record is created.

Be aware that you can't call update() (或 IDBCursor.delete() ) on cursors obtained from IDBIndex.openKeyCursor() . For such needs, you have to use IDBIndex.openCursor() 代替。

注意： 此特征可用于 Web 工作者 .

句法

var anIDBRequest = myIDBCursor.update(value);

参数

值

返回值

IDBRequest object on which subsequent events related to this operation are fired.

异常

此方法可能引发 DOMException of one of the following types:

异常	描述
`TransactionInactiveError`	This IDBCursor's transaction is inactive.
`ReadOnlyError`	The transaction mode is read only.
`InvalidStateError`	The cursor was created using `IDBIndex.openKeyCursor` , is currently being iterated, or has iterated past its end.
`DataError`	The underlying object store uses in-line keys and the property in the value at the object store's key path does not match the key in this cursor's position.
`DataCloneError`	The data being stored could not be cloned by the internal structured cloning algorithm.

范例

In this simple fragment we create a transaction, retrieve an object store, then use a cursor to iterate through all the records in the object store. If the albumTitle of the current cursor is "A farewell to kings", we update year the album was released using var request = cursor.update(); .

Note that you cannot change primary keys using cursor.update() , hence us not changing the album title; this would ruin the integrity of the data. In such a situation, you would have to delete the record altogether and then add a new one using IDBObjectStore.add . Note also that you can't directly put cursor.value into an update call, hence the below example using an intermediary updateData 变量。

T he cursor does not require us to select the data based on a key; we can just grab all of it. Also note that in each iteration of the loop, you can grab data from the current record under the cursor object using cursor.value.foo . For a complete working example, see our IDBCursor example ( 实时查看范例 )。

function updateResult() {
  list.innerHTML = '';
  const transaction = db.transaction(['rushAlbumList'], 'readwrite');
  const objectStore = transaction.objectStore('rushAlbumList');
  objectStore.openCursor().onsuccess = function(event) {
    const cursor = event.target.result;
    if (cursor) {
      if (cursor.value.albumTitle === 'A farewell to kings') {
        const updateData = cursor.value;
        updateData.year = 2050;
        const request = cursor.update(updateData);
        request.onsuccess = function() {
          console.log('A better album year?');
        };
      };
      const listItem = document.createElement('li');
      listItem.innerHTML = '<strong>' + cursor.value.albumTitle + '</strong>, ' + cursor.value.year;
      list.appendChild(listItem);
      cursor.continue();
    } else {
      console.log('Entries displayed.');
    }
  };
};

规范

规范	状态	注释
索引数据库 API 2.0 The definition of 'update()' in that specification.	推荐
索引数据库 API 草案 The definition of 'update()' in that specification.	推荐

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`update`	Chrome 24 24 不支持 23 — 24 Prefixed Prefixed Implemented with the vendor prefix: webkit	Edge 12	Firefox 16 16 不支持 10 — 16 Prefixed Prefixed Implemented with the vendor prefix: moz	IE 部分支持 10	Opera 15	Safari 7	WebView Android Yes	Chrome Android Yes	Firefox Android 22	Opera Android 14	Safari iOS 8	Samsung Internet Android Yes

图例

完整支持
部分支持
要求使用供应商前缀或不同名称。

另请参阅

使用 IndexedDB
开始事务： IDBDatabase
使用事务： IDBTransaction
设置一系列键： IDBKeyRange
检索并使您的数据改变： IDBObjectStore
使用光标： IDBCursor
参考范例：待办通知 ( 实时查看范例 )。

元数据

最后修改： 2020 年 1 月 22 日

IndexedDB API
IDBCursor
特性
1. direction
2. key
3. primaryKey
4. request
5. source
方法
1. advance()
2. continue()
3. continuePrimaryKey()
4. delete()
5. update()
IndexedDB 相关页面

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句法

参数

返回值

异常

范例

规范

浏览器兼容性

图例

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