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---
title: IDBObjectStore.get()
slug: Web/API/IDBObjectStore/get
translation_of: Web/API/IDBObjectStore/get
---
<p>{{ APIRef("IndexedDB") }}</p>
<div>
<p>{{domxref("IDBObjectStore")}} 的接口 <strong><code>get()</code></strong>方法 返回 {{domxref("IDBRequest")}} 对象，并在“单独的线程（separate thread）”中返回由指定键选择的“对象储存（object store）” 。这用于从对象储存检索特定记录。</p>
</div>
<p>如果成功找到值，则会创建其值的结构化克隆，并设置为“请求对象（request object）”的 <code><a href="/en/IndexedDB/IDBRequest#attr_result" title="en/IndexedDB/IDBRequest#attr result">result</a></code> 。</p>
<p>{{ Note("This method produces the same result for: a) a record that doesn't exist in the database and b) a record that has an undefined value. To tell these situations apart, call the <code>openCursor()</code> method with the same key. That method provides a cursor if the record exists, and no cursor if it does not.") }}</p>
<p>{{AvailableInWorkers}}</p>
<h2 id="语法">语法</h2>
<pre class="syntaxbox notranslate">var <em>request</em> = <em>objectStore</em>.get(<em>key</em>);</pre>
<h3 id="参数">参数</h3>
<dl>
<dt>key</dt>
<dd><span style="">标识要检索的记录的键或键范围</span>。</dd>
</dl>
<h3 id="返回值">返回值</h3>
<p><span style="">触发与此操作相关的后续事件的</span> {{domxref("IDBRequest")}} 对象。</p>
<h3 id="异常"><span style="">异常</span></h3>
<p><span style="">此方法可能会引发以下类型之一的</span> <span style="line-height: 1.5;"> {{domxref("DOMException")}} :</span></p>
<table class="standard-table">
<thead>
<tr>
<th scope="col">Exception</th>
<th scope="col">Description</th>
</tr>
</thead>
<tbody>
<tr>
<td><font face="Courier New, Andale Mono, monospace"><span style="line-height: normal;">TransactionInactiveError</span></font></td>
<td>This {{domxref("IDBObjectStore")}}'s transaction is inactive.</td>
</tr>
<tr>
<td><font face="Courier New, Andale Mono, monospace"><span style="line-height: normal;">DataError</span></font></td>
<td>
<p>The key or key range provided contains an invalid key.</p>
</td>
</tr>
<tr>
<td><code>InvalidStateError</code></td>
<td>The {{domxref("IDBObjectStore")}} has been deleted or removed.<br>
</td>
</tr>
</tbody>
</table>
<h2 id="例子">例子</h2>
<p>在以下的代码段中，我们在数据库上打开一个“读/写 事务（read/write transaction）”，并使用 <code>get()</code> 从“对象储存（ object store ）”中获取一个特定的记录——一个带有“Walk dog”键的示例记录。一旦检索到这个数据对象，你就可以使用普通的JavaScript更新它，然后使用 {{domxref("IDBObjectStore.put")}} 操作将其放回数据库。有关完整的工作示例，查看我们的 <a href="https://github.com/mdn/to-do-notifications/" style="line-height: 1.5;">To-do Notifications</a><span style="line-height: 1.5;"> app (</span><a href="http://mdn.github.io/to-do-notifications/" style="line-height: 1.5;">view example live</a><span style="line-height: 1.5;">.)</span></p>
<pre class="brush: js notranslate">// Let us open our database
<span style="line-height: 1.5;">var DBOpenRequest = window.indexedDB.open("toDoList", 4);
</span><span style="line-height: 1.5;">DBOpenRequest.onsuccess = function(event) {</span>
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 getData() function to get the data from the database
getData();
};
function getData() {
// open a read/write db transaction, ready for retrieving the data
var transaction = db.transaction(["toDoList"], "readwrite");
// report on the success of the transaction completing, when everything is done
transaction.oncomplete = function(event) {
note.innerHTML += '<li>Transaction completed.</li>';
};
transaction.onerror = function(event) {
note.innerHTML += '<li>Transaction not opened due to error: ' + transaction.error + '</li>';
};
// create an object store on the transaction
var objectStore = transaction.objectStore("toDoList");
// Make a request to get a record by key from the object store
var objectStoreRequest = objectStore.get("Walk dog");
objectStoreRequest.onsuccess = function(event) {
// report the success of our request
note.innerHTML += '<li>Request successful.</li>';
var myRecord = objectStoreRequest.result;
};
};</pre>
<h2 id="规范"><span style="font-size: 2.14285714285714rem;">规范</span></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', '#dom-idbobjectstore-get', 'get()')}}</td>
<td>{{Spec2('IndexedDB')}}</td>
<td></td>
</tr>
<tr>
<td>{{SpecName("IndexedDB 2", "#dom-idbobjectstore-get", "get()")}}</td>
<td>{{Spec2("IndexedDB 2")}}</td>
<td></td>
</tr>
</tbody>
</table>
<h2 id="Browser_compatibility" name="Browser_compatibility">浏览器兼容性</h2>
<div>
<p>{{Compat("api.IDBObjectStore.get")}}</p>
</div>
<h2 id="另请参阅">另请参阅</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>
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