Question

我正在将一些数据存储在indexedDb中。

我创建了一个将数据保存到indexedDb的方法。我已经存储了49条记录。我正在尝试检索所有这些。我已经写了下面的代码来获取值。我的js文件中不存在除此行之外的其他代码。

function crap() {
var indexedDb = window.indexedDB || window.webkitIndexedDB || window.msIndexedDB;

var IDBKeyRange = window.IDBKeyRange || window.webkitIDBKeyRange;

var openedDb = indexedDb && indexedDb.open;

var isIndexDbTransactionPossible = window.IDBTransaction || window.webkitIDBTransaction;
if (isIndexDbTransactionPossible) {
    isIndexDbTransactionPossible.READ_WRITE = isIndexDbTransactionPossible.READ_WRITE || 'readwrite';
    isIndexDbTransactionPossible.READ_ONLY = isIndexDbTransactionPossible.READ_ONLY || 'readonly';
}

var request = indexedDb.open('Offline', DB_VERSION);

request.onupgradeneeded = function(e) {
    var db = e.target.result;

    if (db.objectStoreNames.contains('tab')) {
        db.deleteObjectStore('tab');
    }

    var store = db.createObjectStore('tab', {keyPath: 'id', autoIncrement: true});
};

request.onsuccess = function(e) {
    console.log("DB opened");
    var db = e.target.result;

    var store= db.transaction('tab', IDBTransaction.READ_ONLY).objectStore('tab');

    var cursor = store.openCursor();

    cursor.onsuccess = function(event) {

        var c = event.target.result;

        if (c) {
            console.log("New value")
            c.continue();
        }
    };
};
}

我看到＆＃34;新价值＆＃34;印刷了124次。我不确定为什么cursor.continue（）在第49次尝试后没有返回null。非常感谢任何帮助。

我很肯定这种方法不会被多次调用。＆＃34; DB打开＆＃34;只记录一个。

Answer 1

只需检查游标请求回调中是否定义了游标，而不是检查readyState。这是一个例子。为清楚起见，我稍微修改了变量的名称。

cursorRequest.onsuccess = function(event) {
  var cursor = event.target.result;

  if(cursor) {
    var value = cursor.value;
    console.log('New value:', value);
    cursor.continue();
  } else {
    // Undefined cursor. This means either no objects found, 
    // or no next object found
    // Do not call cursor.continue(); in this else branch because 
    // there are no more objects over which to iterate.  
    // Coincidentally, this also means we are done iterating.
    console.log('Finished iterating');
  }
}

Answer 2

只需使用getAll函数：

    var allRecords = store.getAll();
    allRecords.onsuccess = function() {
        console.log(allRecords.result);
    };

在文档中了解更多信息：Working with IndexedDB

如何从indexeddb

2 个答案: