未捕获的 DOMException：无法从"IDBRequest"读取'result'属性：请求尚未完成

Question

我通过从另一个javascript文件中调用一个方法，将数据绑定到3个下拉列表。从IndexedDB加载下拉列表的数据源。数据绑定JS、

function bindStateData(){
getMstStates("#state");
getMstStates("#drstate");
getMstStates("#cstate");
}

数据库管理器js，

function getMstStates(state) {
var request = indexedDB.open('AppDatabase', '3')
request.onsuccess = function (e) {
var dbInstance = e.target.result;
let transaction = dbInstance.transaction("MstStates", "readonly");
const statesDetailsStore = transaction.objectStore("MstStates");
stateData = statesDetailsStore.getAll();
stateData.onsuccess = function () {
var MstStatesMap = new Object();
var len = stateData.result.length,
i;
for (i = 0; i < len; i++) {
MstStatesMap[i] = {};
MstStatesMap[i].StateId = stateData.result[i].StateId;
MstStatesMap[i].StateName = stateData.result[i].StateName;
}
callBackOptionItems(MstStatesMap, state);
}
stateData.onerror = function () {
console.log('getMstStates : ' + e);
}
}
request.onerror = function (e) { console.log('getMstStates : ' + e); }
}
function callBackOptionItems(MstOptionMap, objID) {
for (var j in MstOptionMap) {
var k, v
var tem = 0;
for (var i in MstOptionMap[j]) {
if (tem == 0) {
k = MstOptionMap[j][i]
} else {
v = MstOptionMap[j][i];
}
tem++
}
var el = $(objID);
$(el).append('<option value="' + k + '">' + v + '</option>');
}
if (objID == '#select-history') {
$("#select-history").append('<option value="4">Other</option>');
}
}

当我试图加载数据时，我得到了以下错误，

Uncaught DOMException: Failed to read the 'result' property from 'IDBRequest': The request has not finished.
at IDBRequest.stateData.onsuccess

同样的代码逻辑是在WebSQL中编写的，它运行正常，但不幸的是，iOS 13版本的WebSQL支持已被撤销。

Answer 1

我已经解决了这个问题。罪魁祸首是

var len = stateData.result.length;

正确的代码如下，

var _request = statesDetailsStore.getAll();
_request.onsuccess = function (event) {
var MstStatesMap = new Object();
var stateData = event.target.result;
}