我有以下结构的代码（伪代码）： 页面初始化（应用程序启动）： a] getDateRange - ＆gt;获取日期范围数组（例如包含10个项目的数组） b] getResultFromDatabaseForDateRange - ＆gt;每次调用后返回JSON对象的Assync任务
我想在每个循环中调用 b 方法，并将每个JSON数组对象存储返回到类全局变量中。收到 b 的所有回复后，我想将整个填充的对象设置为范围。
有人能给我一个例子，我怎样才能以正确的方式做到这一点？
感谢您的任何建议。
我试图通过这种方式做到这一点，但它不起作用（代码因长度而简化）：
$scope.getDateRange = function(direction) {
console.log('Trying to set date range for ' +direction);
switch(direction) {
case 'today':
console.log("Trying to set date range for this week - "+countOfWeeksInPast+" weeks");
dateTo = moment().day(7).format('YYYY-MM-DD');
dateFrom = moment().day(1).format('YYYY-MM-DD');
console.log(dateTo);
console.log(dateFrom);
// CREATE THIS WEEK - 10 WEEKS RANGE IN PAST
for (var i = 0; i < countOfWeeksInPast; i++) {
var row = {};
if(i==0) {
row.ID = i;
row.DATE_TO = dateTo;
row.DATE_FROM = dateFrom;
dateRanges.push(row);
} else {
row.ID = i;
row.DATE_TO = dateTo = moment(dateTo).subtract(7, 'days').format('YYYY-MM-DD');
row.DATE_FROM = dateFrom = moment(dateFrom).subtract(7, 'days').format('YYYY-MM-DD');
dateRanges.push(row);
}
}
$scope.getResultFromDatabaseForDateRange('create_new').then(function(result){
// THIS GIVES THE VALUE:
//alert("Result is" + JSON.stringify(result));
console.log("Returned Result is: " + JSON.stringify(result));
//return result;
}, function(e){
$ionicLoading.show({
template: $translate.instant('ERROR_DATABASE'),
duration:1000
});
});
}
};
$scope.getResultFromDatabaseForDateRange = function(listAction) {
console.log('trying to get data for selected date ranges');
// SHOW LOADING MESSAGE
$ionicLoading.show({
template: 'Loading data'
});
var deferred = $q.defer();
// INSTANTIATE DB CONNECTION
db = window.sqlitePlugin.openDatabase({name:"callplanner"});
var ic=0;
for(ic; ic < dateRanges.length; ic++) {
var sqlQuery =
"SELECT '"+dateRanges[ic].DATE_FROM+"' as DATE_FROM, "+
" '"+dateRanges[ic].DATE_TO+"' as DATE_TO, "+
" COUNT(*) AS DIALS_CNT, "+
" SUM(CASE WHEN dc.call_result = '"+CALL_RESULT_STATE_APPT+"' THEN 1 ELSE 0 END) AS '"+APPT_CNT+"', "+
" SUM(CASE WHEN dc.call_result = '"+CALL_RESULT_STATE_CONV_NO_APPT+"' THEN 1 ELSE 0 END) AS '"+CONVERS_CNT+"' , "+
" SUM(CASE WHEN dc.call_result = '"+CALL_RESULT_STATE_CANNOT_REACH+"' THEN 1 ELSE 0 END) AS '"+CANNOT_REACH_CNT+"' "+
" FROM "+DIALED_CALLS_TABLE+" dc "+
" WHERE dc.date BETWEEN '"+dateRanges[ic].DATE_FROM+"' AND '"+dateRanges[ic].DATE_TO+"';";
console.log(sqlQuery);
db.transaction(function(tx) {
// init empty array for results
tx.executeSql(sqlQuery, [], function(tx,results){
for (var i=0; i < results.rows.length; i++){
row = results.rows.item(i);
//Udpate date for writeout
//row.DATE = moment(row.DATE).format('ddd DD.M');
//row.SUCCES_RATE = DialsCompute.computeSuccessRateDaily(row);
listData.push(row);
console.log("row is " + JSON.stringify(row));
}
console.log(JSON.stringify(listData));
});
},function (e) {
console.log("ERROR: " + e.message);
deferred.reject(e);
});
}
deferred.resolve(row);
$ionicLoading.hide();
return deferred.promise;
};
答案 0 :(得分：0)
您需要计算处理的行数，当它等于需要读取的行数时，您应该解决您的承诺。所以在你的情况下：
var numberOfProcessed = 0;
for(ic; ic < dateRanges.length; ic++) {
var sqlQuery ="..."
db.transaction(function(tx) {
// init empty array for results
tx.executeSql(sqlQuery, [], function(tx,results){
//process your result from sql
numberOfProcessed++;
if(numberOfProcessed == dateRanges.length){
deferred.resolve(resultObject); // resolve your promise when you are sure you handled everything
}
console.log(JSON.stringify(listData));
});
},function (e) {
console.log("ERROR: " + e.message);
deferred.reject(e);
});
}
btw getResultFromDatabaseForDateRange需要成为服务，业务逻辑或与后端服务等的连接的一部分，不应成为控制器的一部分。
答案 1 :(得分：0)
对于我的新闻自动收报机指令，我创建了以下内容：
//method call
fetchData($scope.verbs).then(function (messageModel) {
$scope.messageModel = messageModel;
$scope.toggleTimer();
}, function (data) {
$element.css("display", "none");
$log.error("error: " + data.message);
});
//helper functions
function fetchData(verbs) {
return checkRequiredVerbs(verbs)
.then(getDataFromSource)
.then(prepareMessages);
};
function checkRequiredVerbs(verbs) {
var deferred = $q.defer(),
arrRequiredVerbs = configManager.baseUrl.split(/\/:/g);
if (angular.isObject(verbs)) {
for (var i = 1; i < arrRequiredVerbs.length; i++) {
if (!verbs.hasOwnProperty(arrRequiredVerbs[i])) {
deferred.reject({message: "Verb '" + arrRequiredVerbs[i] + "' is unknown"});
break;
}
}
deferred.resolve(verbs);
} else {
deferred.reject({message: "Wrong verb syntax!"});
}
return deferred.promise;
};
function getDataFromSource(verbs) {
return messageLoaderFactory.query(verbs).$promise;
};
function prepareMessages(messageModel) {
var deferred = $q.defer(),
tmpMessageModel = [];
for (var i = 0; i < messageModel.length; i++) {
messageModel[i].visible = (i === 0);
}
deferred.resolve(messageModel);
return deferred.promise;
};
}}
在我从服务中获取数据之前，我必须检查输入参数。首先会调用函数fetchData。在此函数内部，将调用checkRequiredVerbs函数并返回Promise。此承诺将转移到下一个函数getDataFromSource并返回另一个Promise。最后，将调用函数prepareMessages。当某些事情发生时，所有行动都会停止，新闻自动收报机将被隐藏。
完整的项目可以找到here