Angular.js 通过 2 个给定属性在数组中搜索匹配对象

Question

我有 table 的 CItyDistance：CIty1Id|City2Id|Distance(KM)，现在在我的项目中我收到了 2 个城市的 ID，我想检查是否有计算这 2 个城市的距离。

所以无论谁是 City1 或 City2 都无关紧要，我需要检查这两个选项。我发现检查它的方式太长而且混乱。谁能提供替代方案？（请检查 Plunker 示例：https://plnkr.co/edit/nzB8zy0034LqJFgL8qk7?p=preview

 $scope.CompanyCity = { Id: 59, Name: 'berline' };

 $scope.result = "";

 $scope.distances = [ 
 {city1: 59,city2: 1,  Distance: 50 }, 
 {city1: 1, city2: 58, Distance: 80 },
 {city1: 3, city2: 59, Distance: 25 },
 {city1: 4, city2: 1,  Distance: 120 }];


 $scope.findDistance = function(studentCityID) {
    angular.forEach($scope.distances, function(value, key) {
        if (value.city1 == studentCityID && value.city2 == $scope.CompanyCity.Id) {
            $scope.result = value.Distance;
        } 
        else if (value.city2 == studentCityID && value.city1 == $scope.CompanyCity.Id) {
            $scope.result = value.Distance;
        }
    });
};
$scope.findDistance(1);

Answer 1

由于 json 结构，我认为您实现的很好。我只能建议下面的代码

$scope.findDistance = function(studentCityID) {
    for (var count=0; count<$scope.distances.length; count++) {
      if (($scope.distances[count].city1 == studentCityID && $scope.distances[count].city2 == $scope.CompanyCity.Id) || 
          ($scope.distances[count].city2 == studentCityID && $scope.distances[count].city1 == $scope.CompanyCity.Id)) {
          $scope.result = $scope.distances[count].Distance;
          break;
      }
    }
};

如果有帮助请告诉我！

Answer 2

你可以试试这个，把你的$scope.findDistance函数换成这个。我认为它有更少的代码和有效的方式来满足您的要求。

 $scope.findDistance = function(studentCityID) {
    angular.forEach($scope.distances, function(value, key) {
        var arr = Object.values(value);
        if(arr.indexOf(studentCityID) !== -1 && arr.indexOf($scope.CompanyCity.Id) !== -1) {
               $scope.result = value.Distance;
        }
    });
};

添加了 plunker，https://plnkr.co/edit/3r3intufeiqc26kzcnca?p=preview

谢谢，祝你好运:)

Answer 3

使用下面的方法和运算符来优化您的代码：

使用 Array filter() 方法迭代数组并创建一个新数组，其中包含通过提供的函数实现的测试的所有元素。
使用 JavaScript ternary operator 此运算符经常用作 if 语句的快捷方式。

var myApp = angular.module('myApp',[]);

myApp.controller('MyCtrl',function($scope) {

$scope.CompanyCity = { Id: 59, Name: 'berline' };

$scope.distances = [ 
  {city1: 59,city2: 1,  Distance: 50 }, 
  {city1: 1, city2: 58, Distance: 80 },
  {city1: 3, city2: 59, Distance: 25 },
  {city1: 4, city2: 1,  Distance: 120 }
];


$scope.findDistance = function(studentCityID) {
    var res = $scope.distances.filter(function(item) {
        return (item.city1 == studentCityID && item.city2 == $scope.CompanyCity.Id) ? item.Distance : ((item.city2 == studentCityID && item.city1 == $scope.CompanyCity.Id) ? item.Distance : '');    
    });
    console.log(res[0].Distance); // Distance
};
$scope.findDistance(1); 
});

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<div ng-app="myApp" ng-controller="MyCtrl">
</div>

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