objectStore.openCursor().onsuccess 没有被调用

Question

我刚开始使用 indexedDB。

我能够在对象存储中写入数据并在第一次点击时获取数据。 当我尝试再次点击时，我观察到将数据写入 DB 可以正常工作，但似乎无法调用 OpenCursor.Success。

谁能指出差距？

这是我的代码..

function clickMe()
{
alert("Yes am inside the function..");
window.indexedDB = window.indexedDB || window.mozIndexedDB || window.webkitIndexedDB || window.msIndexedDB;
window.IDBTransaction = window.IDBTransaction || window.webkitIDBTransaction || window.msIDBTransaction;
window.IDBKeyRange = window.IDBKeyRange || window.webkitIDBKeyRange || window.msIDBKeyRange;

try {
  var dbOpenRequest = window.indexedDB.open("MyDB");
  alert("congretss I Opened The DB as well..");

  dbOpenRequest.onsuccess = function(event){
  try {
     alert("I am inside the onsuccess Method");
     var db = dbOpenRequest.result;
     db.onerror=function(event){

     }; 

     var transaction = db.transaction(["My_ObjectStore"], "readwrite");

      transaction.oncomplete = function(e){

      };
      transaction.onabort = function(e){

      };
      transaction.onerror = function(e){

      };


      try {
        var objectStore = transaction.objectStore("My_ObjectStore");
       alert("Wait am trying to write the data in DB..");
        var objectId = new Date().getTime()
                    var data =([ {
                    "reference": "<a href='details.html'>DEV2014/557</a>",
                    "applicant": "Association",
                    "siteAddress": "631 Gregory Terrace, Bowen Hills",
                    "applicationType": "Decided Application",
                    "status": "Approved",
                    "action": "<a href='details.html' class='btn btn-primary'>View Details</a>",
                    "id": 1
                    },
                     {
                    "reference": "<a href='details.html'>DEV2014/557</a>",
                    "applicant": "Association",
                    "siteAddress": "631 Gregory Terrace, Bowen Hills",
                    "applicationType": "Decided Application",
                    "status": "Approved",
                    "action": "<a href='details.html' class='btn btn-primary'>View Details</a>",
                    "id": 2
                    }
                    ]);

        for(i in data)
        {
        var request = objectStore.add(data[i]);  
        }
        alert("Writing data is finished.."+request);

        //get all the data using cursor 
        objectStore.openCursor().onsuccess = function(event) {
        alert("Now you can See the Data..");
         var cursor = event.target.result;

         if (cursor) {
            alert(cursor.value.id);

            cursor.continue();
            } 
             else {
            //alert("No more entries!");
                }     
           };   

        }catch(e){alert("error while writting the data");}



    }catch (e){         
            alert("An error occured when creating object store");
            writeError(e);
            }
     };

 dbOpenRequest.onupgradeneeded = function(event){
 try{
     var db = dbOpenRequest.result;
     var transaction = dbOpenRequest.transaction;
     var objectStore = db.createObjectStore("My_ObjectStore",{
        "keyPath": "id",
        "autoIncrement": true
      });
       }catch(e){alert("Error while crating object store");}
    };
  }
catch(e){alert("error");}
}

Answer 1

我观察到将数据写入数据库很顺利

我只是复制/粘贴并测试了您的代码，第一次编写运行良好，但其他代码没有（您可以使用浏览器调试工具查看 indexeddb 内容）。

原因： 您每次都设置相同的主键：

"id": 1
"id": 2

所以我无法真正解释为什么您的打开游标在那之后失败（可能是因为您的对象存储请求处于错误状态？），但这似乎是问题所在......