Question

请查看我的代码。

  var posts = PostsData.getPosts();   
  var postFunc = function(key) {
      return posts[key];  
  }

  $scope.$watch($scope.active, function() {
      $timeout(function() {
    var markers = [];

    for (var key in posts) {

          console.log(key);
          var p = gf.get(key).then(function(location) { 
          var post = postFunc(key);
          console.log(key);
          return ({
            idKey: key,
            title: post.title,
            coords: {
              latitude: location[0],
              longitude: location[1]
            }
           });
      });
      markers.push(p);

    }

    $q.all(markers).then(function(markers) {
    $scope.markers = markers;
    });

  });
})

}

在循环中有两行＆＃34; console.log（key）＆＃34;。第一个console.log打印数据的准确表示，这是唯一键。第二个console.log打印重复的相同数据，这是不准确的。我无法理解为什么会这样。

非常感谢您的帮助。

Answer 1

从第二SQL> create table app as 2 with app (app_ver, num_subversions) as ( 3 select 'A', 2 from dual union all 4 select 'B', 3 from dual union all 5 select 'C', 4 from dual 6 ) 7 select app_ver, num_subversions 8 from app a; Table created SQL> with a1 (app_ver, num_subversions, lvl) as ( 2 select app_ver, num_subversions, 1 3 from app 4 union all 5 select app.app_ver, app.num_subversions, a1.lvl + 1 6 from app, a1 7 where app.app_ver = a1.app_ver 8 and a1.lvl < app.num_subversions) 9 search depth first by app_ver, num_subversions set my_order 10 select app_ver || lvl 11 from a1; APP_VER||LVL ----------------------------------------- A1 A2 B1 B2 B3 C1 C2 C3 C4 9 rows selected开始你有相同的价值是很正常的。原因是你的异步函数console.log(key)。调用此函数时，循环已完成执行， gf.get(key).then(function(location) { .. }的值是循环中的最后一个值。我不确定key是做什么的，但如果gf.get是一个数组，你可以通过递归帮助实现你的结果，如下所示

posts

注意：在此方法中，我们等待每个承诺得到解决，然后再转到下一个var posts = PostsData.getPosts(); var postFunc = function(key) { return posts[key]; } var markers = []; var getMarkers(key) { if (key > posts.length - 1) { // promise resolved for each item in posts $q.all(markers).then(function(markers) { $scope.markers = markers; } return; } console.log(key); gf.get(key).then(function(location) { var post = postFunc(key); console.log(key); markers.push({ idKey: key, title: post.title, coords: { latitude: location[0], longitude: location[1] } }); getMarkers(++key); }); } $scope.$watch($scope.active, function() { markers = []; getMarkers(0); });

Answer 2

解决问题的另一种方法是使用IIFE闭包。

key

通过使用IIFE（Immediately Invoked Function Expression），每个.then的值都会保留，直到#pragma mark - Previewing delegate - (UIViewController *)previewingContext:(id <UIViewControllerPreviewing>)previewingContext viewControllerForLocation:(CGPoint)location { UIViewController *detailVC = [self.storyboard instantiateViewControllerWithIdentifier:@"detail"]; detailVC.preferredContentSize = CGSizeMake(0.0, 568.0); previewingContext.sourceRect = self.btnDetail.frame; return detailVC; } - (void)previewingContext:(id <UIViewControllerPreviewing>)previewingContext commitViewController:(UIViewController *)viewControllerToCommit{ [self showViewController:viewControllerToCommit sender:self]; }方法内的函数完成。

使用geofire和firebase循环遍历数组时重复数据

2 个答案: