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---
title: IDBOpenDBRequest
slug: Web/API/IDBOpenDBRequest
translation_of: Web/API/IDBOpenDBRequest
---
<p>{{APIRef("IndexedDB")}}</p>
<div>
<p>IndexedDB API 的 <strong><code>IDBOpenDBRequest</code></strong> 接口提供了访问打开或删除数据库的请求的结果（通过调用 {{domxref("IDBFactory.open")}} and {{domxref("IDBFactory.deleteDatabase")}}），途径就是使用特殊的事件处理器属性。</p>
</div>
<p>{{AvailableInWorkers}}</p>
<p>{{InheritanceDiagram}}</p>
<h2 id="Properties">Properties</h2>
<p><em>Also inherits methods from its parents {{domxref("IDBRequest")}} and {{domxref("EventTarget")}}</em>.</p>
<h3 id="Events">Events</h3>
<dl>
<dt>{{domxref("IDBOpenDBRequest.onblocked")}}</dt>
<dd>The event handler for the blocked event. This event is triggered when the <code>upgradeneeded</code> event should be triggered because of a version change but the database is still in use (i.e. not closed) somewhere, even after the <code>versionchange</code> event was sent.</dd>
<dt>{{domxref("IDBOpenDBRequest.onupgradeneeded")}}</dt>
<dd><code>upgradeneeded</code> 事件的事件处理器，会在当一个数据库的版本比已经存在的版本还高的时候触发。</dd>
<dt>
<h2 id="Methods">Methods</h2>
<p><em>No methods, but inherits methods from its parents {{domxref("IDBRequest")}} and {{domxref("EventTarget")}}.</em></p>
</dt>
</dl>
<h2 id="Example">Example</h2>
<p>In the following example you can see the onupgradeneeded handler being used to update the database structure if a database with a higher version number is loaded. For a full working example, see our <a class="external" href="https://github.com/mdn/to-do-notifications/tree/gh-pages">To-do Notifications</a> app (<a class="external" href="http://mdn.github.io/to-do-notifications/">view example live</a>.)</p>
<pre class="brush: js; highlight:[16,28,29,31,32,33,34,35,36]">var db;
// Let us open our database
var DBOpenRequest = window.indexedDB.open("toDoList", 4);
// these event handlers act on the database being opened.
DBOpenRequest.onerror = function(event) {
note.innerHTML += '<li>Error loading database.</li>';
};
DBOpenRequest.onsuccess = function(event) {
note.innerHTML += '<li>Database initialised.</li>';
// store the result of opening the database in the db
// variable. This is used a lot below
db = DBOpenRequest.result;
// Run the displayData() function to populate the task
// listwith all the to-do list data already in the IDB
displayData();
};
// This event handles the event whereby a new version of
// the database needs to be created Either one has not
// been created before, or a new version number has been
// submitted via the window.indexedDB.open line above
// it is only implemented in recent browsers
DBOpenRequest.onupgradeneeded = function(event) {
var db = this.result;
db.onerror = function(event) {
note.innerHTML += '<li>Error loading database.</li>';
};
// Create an objectStore for this database
var objectStore = db.createObjectStore("toDoList", { keyPath: "taskTitle" });
// define what data items the objectStore will contain
objectStore.createIndex("hours", "hours", { unique: false });
objectStore.createIndex("minutes", "minutes", { unique: false });
objectStore.createIndex("day", "day", { unique: false });
objectStore.createIndex("month", "month", { unique: false });
objectStore.createIndex("year", "year", { unique: false });
objectStore.createIndex("notified", "notified", { unique: false });
};</pre>
<h2 id="Specifications">Specifications</h2>
<table class="standard-table">
<tbody>
<tr>
<th scope="col">Specification</th>
<th scope="col">Status</th>
<th scope="col">Comment</th>
</tr>
<tr>
<td>{{SpecName('IndexedDB', '#idl-def-IDBOpenDBRequest', 'IDBOpenDBRequest')}}</td>
<td>{{Spec2('IndexedDB')}}</td>
<td>Initial definition</td>
</tr>
<tr>
<td>{{SpecName("IndexedDB 2", "#idbopendbrequest", "IDBOpenDBRequest")}}</td>
<td>{{Spec2("IndexedDB 2")}}</td>
<td> </td>
</tr>
</tbody>
</table>
<h2 id="Browser_compatibility">Browser compatibility</h2>
<div>
<p>{{Compat("api.IDBOpenDBRequest")}}</p>
</div>
<h2 id="See_also">See also</h2>
<ul>
<li><a href="/en-US/docs/Web/API/IndexedDB_API/Using_IndexedDB">Using IndexedDB</a></li>
<li>Starting transactions: {{domxref("IDBDatabase")}}</li>
<li>Using transactions: {{domxref("IDBTransaction")}}</li>
<li>Setting a range of keys: {{domxref("IDBKeyRange")}}</li>
<li>Retrieving and making changes to your data: {{domxref("IDBObjectStore")}}</li>
<li>Using cursors: {{domxref("IDBCursor")}}</li>
<li>Reference example: <a class="external" href="https://github.com/mdn/to-do-notifications/tree/gh-pages">To-do Notifications</a> (<a class="external" href="http://mdn.github.io/to-do-notifications/">view example live</a>.)</li>
</ul>
|
