javascript - 在 AngularJS 中顺序运行 $http 请求

Question

我的 $scope 上有一组项目。对于其中的每一项，我都需要运行三个 $http 请求。这些请求必须以特定的顺序运行，无论是否有 not 失败。我不确定如何使用 promise 范式优雅地做到这一点。我有很多重复的代码，看起来真的很困惑。我一定是做错了。目前，我有以下内容:

$scope.items = getItems();
$scope.currentIndex = 0;

$scope.executeItem = function() {
  $http.get($scope.items[$scope.currentIndex].urlA).then(
    function (resA) {
      $scope.items[$scope.currentIndex].urlAWorks = true;
      $http.get($scope.items[$scope.currentIndex].urlB).then(
        function (resB) {
          $scope.items[$scope.currentIndex].urlBWorks = true;

          $http.get($scope.items[$scope.currentIndex].urlC).then(
            function (resC) {
              $scope.items[$scope.currentIndex].urlCWorks = true;
              $scope.currentIndex = $scope.currentIndex + 1;
              $scope.executeItem();
            },

            function (errC) {
              $scope.items[$scope.currentIndex].urlCWorks = false;
              $scope.currentIndex = $scope.currentIndex + 1;
              $scope.executeItem();
            }
          )
        },
        function (errB) {
          $scope.items[$scope.currentIndex].urlBWorks = false;
        }
      );
    },

    function (errA) {
      $scope.items[$scope.currentIndex].urlAWorks = false;
      $http.get($scope.items[$scope.currentIndex].urlB).then(
        function (resB) {
          $scope.items[$scope.currentIndex].urlBWorks = true;

          $http.get($scope.items[$scope.currentIndex].urlC).then(
            function (resC) {
              $scope.items[$scope.currentIndex].urlCWorks = true;
              $scope.currentIndex = $scope.currentIndex + 1;
              $scope.executeItem();
            },

            function (errC) {
              $scope.items[$scope.currentIndex].urlCWorks = false;
              $scope.currentIndex = $scope.currentIndex + 1;
              $scope.executeItem();
            }
          )
        },
        function (errB) {
          $scope.items[$scope.currentIndex].urlBWorks = false;
        }
      );
    }
  );
};

我真的正确地链接了 promise 吗？这看起来很不对。

谢谢

Answer 1

你没有充分利用 promises :) 因为 .then 返回一个 promise，你可以这样做:

$http.get(urlA)
  .then(function(dataA){
    DoStuffWithA(dataA);

    return $http.get(urlB);
  })
  .then(function(dataB){
    DoStuffWithB(dataB);

    return $http.get(urlC);
  })
  .then(function(dataC){
    DoStuffWithC(dataC);

    return true;
  })