Question

我是AngularJs的新手。我有一个验证函数，它返回了promise。此函数在内部调用http get api并接收promise响应。我有一些验证码需要来自被叫api的响应。但是在http调用完成并且函数从api接收响应之前，validate函数会向调用者返回promise。这导致验证失败。有人可以分享一些满足这个要求的代码。

function validateDates(delegate) {      
    var currStartDate = delegate.start_date;
    var currEndDate = delegate.end_date;
    var overlap = false;
    var deferred = $q.defer();

    UserDelegateService.getDelegateForUser(delegate.comit_id).then(
        function(res) {
            for(var i = 0; i<res.length; i++) {
                    var sDate = $filter('date')(res[i].start_date, 'yyyy-MM-dd');
                    var eDate = $filter('date')(res[i].end_date, 'yyyy-MM-dd');
                    if(currStartDate <= eDate && sDate <= currEndDate) {
                        overlap = true;         
                        deferred.resolve(overlap);                          
                    } else
                        deferred.reject("Not overlapping"); 
                }
        },
        function(errorresponse) {
            console.log(errorresponse);
        });
    return deferred.promise;
};

调用代码：

$scope.saveDelegate = function() {
    var delegate = {
            //assign values ... 
    };

    var promise = validateDates(delegate);
    promise.then(function(data) {   
        if(data) {
            console.log('Dates are overlapping....if part.......', data);
        }
    }, function(reason) {
            console.log('Dates are not overlapping..saving datlegate..else part.........', reason);
            $scope.save(delegate);
    });
};

Answer 1

使用$q.defer会破坏承诺链并丢失错误信息。此外，正在对for循环的第一项进行解决/拒绝决定。

而是返回值和链。

function validateDates(delegate) {      
    var currStartDate = delegate.start_date;
    var currEndDate = delegate.end_date;
    //var overlap = false;
    //var deferred = $q.defer();

    var p = UserDelegateService.getDelegateForUser(delegate.comit_id);
    var derivedPromise = p.then(
        function onSuccess(res) {
            //Initialize overlap var in success handler
            var overlap = false; 
            for(var i = 0; i<res.length; i++) {
                var sDate = $filter('date')(res[i].start_date, 'yyyy-MM-dd');
                var eDate = $filter('date')(res[i].end_date, 'yyyy-MM-dd');
                if(currStartDate <= eDate && sDate <= currEndDate) {
                     overlap = true;         
                };
            //Return value of overlap for chaining
            return overlap;
        });
    };
    //return derived promise
    return derivedPromise;
};

如果任何日期重叠，则上述函数返回一个解析true的承诺，如果没有任何日期重叠，则会解析false。

客户代码：

$scope.saveDelegate = function() {
    var delegate = {
            //assign values ... 
    };

    var promise = validateDates(delegate);
    promise.then(function onSuccess(overlap) {   
        if(overlap) {
            console.log('Dates are overlapping....if part.......', overlap);
        } else {
            console.log('Dates are not overlapping..saving datlegate..');
            $scope.save(delegate);
        };
    }).catch(function onReject(reason) {
        console.log("Promise rejected for another reason");
    });
};

通过返回和链接承诺，getDelegateForUser操作中的任何错误都会转发到客户端代码。

在http api完成之前，Angular函数返回了promise

1 个答案: