--- 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>