IDBRequest.transaction

在此页

句法
范例
规范
浏览器兼容性
另请参阅
相关话题

transaction read-only property of the IDBRequest interface returns the transaction for the request, that is, the transaction the request is being made inside.

This property can be null for requests not made within transactions, such as for requests returned from IDBFactory.open — in this case you're just connecting to a database, so there is no transaction to return. If a version upgrade is needed when opening a database then during the upgradeneeded event handler the transaction property will be an IDBTransaction with mode 等于 "versionchange" , and can be used to access existing object stores and indexes, or abort the the upgrade. Following the upgrade, the transaction property will again be null .

注意： 此特征可用于 Web 工作者 .

句法

var myTransaction = request.transaction;

值

IDBTransaction .

范例

The following example requests a given record title, onsuccess gets the associated record from the IDBObjectStore (made available as objectStoreTitleRequest.result ), updates one property of the record, and then puts the updated record back into the object store in another request. The source of the requests is logged to the developer console — both originate from the same transaction. For a full working example, see our 待办通知 app ( 实时查看范例 )。

var title = "Walk dog";
// Open up a transaction as usual
var objectStore = db.transaction(['toDoList'], "readwrite").objectStore('toDoList');
// Get the to-do list object that has this title as it's title
var objectStoreTitleRequest = objectStore.get(title);
objectStoreTitleRequest.onsuccess = function() {
  // Grab the data object returned as the result
  var data = objectStoreTitleRequest.result;
  // Update the notified value in the object to "yes"
  data.notified = "yes";
  // Create another request that inserts the item back
  // into the database
  var updateTitleRequest = objectStore.put(data);
  // Log the transaction that originated this request
  console.log("The transaction that originated this request is " + updateTitleRequest.transaction);
  // When this new request succeeds, run the displayData()
  // function again to update the display
  updateTitleRequest.onsuccess = function() {
    displayData();
  };
};

This example shows how a the transaction property can be used during a version upgrade to access existing object stores:

var openRequest = indexedDB.open('db', 2);
console.log(openRequest.transaction); // Will log "null".
openRequest.onupgradeneeded = function(event) {
  console.log(openRequest.transaction.mode); // Will log "versionchange".
  var db = openRequest.result;
  if (event.oldVersion < 1) {
    // New database, create "books" object store.
    db.createObjectStore('books');
  }
  if (event.oldVersion < 2) {
    // Upgrading from v1 database: add index on "title" to "books" store.
    var bookStore = openRequest.transaction.objectStore('books');
    bookStore.createIndex('by_title', 'title');
  }
};
openRequest.onsuccess = function() {
  console.log(openRequest.transaction); // Will log "null".
};

规范

规范	状态	注释
索引数据库 API 2.0 The definition of 'transaction' in that specification.	推荐
索引数据库 API 草案 The definition of 'transaction' 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
`transaction`	Chrome 24 24 23 Prefixed Prefixed Implemented with the vendor prefix: webkit	Edge 12	Firefox 16 16 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
IDBRequest
特性
1. error
2. onerror
3. onsuccess
4. readyState
5. result
6. source
7. transaction
事件
1. error
继承：
1. EventTarget
IndexedDB 相关页面

在此页

句法

值

范例

规范

浏览器兼容性

图例

另请参阅

相关话题