javascript - angularjs从服务获取错误消息到 Controller

Question

使用 REST 获取费率的工厂

.factory('rateResource', ['$resource', function ($resource) {
    return $resource('/rates/:currency/:effectiveDate', {
        currency: '@currency',
        effectiveDate: '@effectiveDate'
    });
}])

调用工厂获取资源并检索费率以及错误(如果有)的服务。

 .service('RateService', ['rateResource', '$rootScope',
    function (rateResource, $rootScope) {
        var self = this;

        self.rates = [];

        self.search = function (baseCurrency, effectiveDate) {
            self.rates = [];
            var error = null;
            self.baseCurrency = baseCurrency;
            self.effectiveDate = effectiveDate;
            if (baseCurrency) {
                rateResource.query({currency: baseCurrency, effectiveDate: effectiveDate})
                    .$promise.then(function (rates) {
                        if (rates) {
                            angular.forEach(rates, function (rate) {
                                rate.maintTs = $rootScope.formatTimestampToHHMMSS(rate.maintTs);
                                rate.editable = false;
                                self.rates.push(rate);
                            });
                            self.processing = false;
                        }
                    }, function (response) {
                        self.processing = false;
                        error = 'Processing failed due to '+response.status;
                        console.log(error);
                    })
                return {
                    rates: self.rates,
                    errors: error
                }
            }
        }
    }]);

Controller 调用服务以获取费率。

.controller('RateController', ['RateService',
    function (rateService) {
        var self = this;

        self.baseCurrency = rateService.getBaseCurrency();
        self.effectiveDate = rateService.getEffectiveDate();
        self.rates = rateService.getRates();

        //make the call from the controller
        self.search = function () {
            var response = rateService.search(self.baseCurrency, self.effectiveDate.yyyyMMdd());
            self.rateRecords = response.rates;
            self.errors = response.errors;
        }
    }])

兑现 promise 后，费率在 Controller 中显示良好。但是，在收到错误后，它们不会从服务传输到 Controller 。 (我更改了 REST URL 以使服务返回 404 响应)。我做错了什么？

Answer 1

当前您正在从异步函数外部返回异步调用响应，从技术上讲您不应该这样做。异步代码总是在其 promise/callback 函数内获得响应。

但就您而言，它正在工作，因为您正在返回带有引用的对象。如果你看下面的代码，return语句已经携带了self.rates对象引用，所以在返回时即使它是空白的，它也会获得更新的值一次self.rates 被填满。因此，您无需担心费率更新。但是对于 error 来说，同样的事情是行不通的，因为它是原始的数据类型，比如 var error = null ，所以当你返回值时，它会是 null 。 >(因为异步响应尚未完成)。

return {
     rates: self.rates, //passed by reference
     errors: error //passed by primitive type
}

因此，为了解决这个问题，您还可以将错误设置为 object 类型，以便它的引用将与引用对象一起传递，例如 varErrors = [] & 当错误发生时，使用 .push

将错误消息推送到该数组中<小时/>

但我不建议采用上述方法，我宁愿使用 promise 模式并维护正确的代码调用堆栈。基本上，您需要从 search 方法返回 Promise，然后放置 .then 函数等待直到解析该函数​​。

服务

.service('RateService', ['rateResource', '$rootScope',
    function(rateResource, $rootScope) {
      var self = this;
      self.rates = [];
      self.search = function(baseCurrency, effectiveDate) {
        self.rates = [];
        var error = null;
        self.baseCurrency = baseCurrency;
        self.effectiveDate = effectiveDate;
        if (baseCurrency) {
          return rateResource.query({
            currency: baseCurrency,
            effectiveDate: effectiveDate
          })
            .$promise.then(function(rates) {
            if (rates) {
              angular.forEach(rates, function(rate) {
                rate.maintTs = $rootScope.formatTimestampToHHMMSS(rate.maintTs);
                rate.editable = false;
                self.rates.push(rate);
              });
              self.processing = false;
            }
            //returning object from promise
            return {
              rates: self.rates,
              errors: error
            }
          }, function(response) {
            self.processing = false;
            error = 'Processing failed due to ' + response.status;
            console.log(error);
            //returning object from promise
            return {
              rates: self.rates,
              errors: error
            }
          })
        }
      }
    }
])

Controller

//make the call from the controller
self.search = function() {
  var response = rateService.search(self.baseCurrency, self.effectiveDate.yyyyMMdd()).then(function() {
    self.rateRecords = response.rates;
    self.errors = response.errors;
  });
}