当我在控制器的函数中传递未定义的字符串时

Question

这是我的HTML：

<!doctype html>
<html ng-app='myApp'>
  <head>
    <title>My Angular App</title>
    <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.4.5/angular.min.js"></script>
    <script src="js/controllers.js"></script>
    <link href="css/bootstrap.min.css" rel="stylesheet">
    <link href="css/font-awesome.min.css" rel="stylesheet">
    <link href="css/style.css" rel="stylesheet">
    <link href='http://fonts.googleapis.com/css?family=Bree+Serif' rel='stylesheet' type='text/css'>
    <link href='http://fonts.googleapis.com/css?family=Open+Sans' rel='stylesheet' type='text/css'>

  </head>
  <body ng-controller='bodyController'>

    <div class="heading">
        <h1>My Social Website</h1>
        <hr>
    </div>

    <div class="postsCss">
        <div ng-repeat="post in posts | orderBy: '-votes'" class="mypost">
            <a ng-show="post.link" href="{{post.link}}">{{post.title}}</a>
            <span ng-hide="post.link"> {{post.title}}</span>
            </br>
            <li class="fa fa-thumbs-o-up" ng-click="upVote(post)"></li>
            <li class="fa fa-thumbs-o-down" ng-click="downVote(post)"></li>
            <span class="counter">{{post.votes}}</span><br>
            <span ng-show="post.comment"> {{post.comment}} </span>
            <br>
            <form ng-submit="addComment(post)" class="myform">
                <input type="text" placeholder="Add a Comment..." ng-model="comment"></input>
                <button class="button" type="submit">Comment</button>
            </form>
        </div>


        <h2>Add a New Post:</h2>
        <form ng-submit="addPost()" class="myform">
            <input type="text" placeholder="Add a Post" ng-model="title"></input><br>
            <input type="text" placeholder="Link" ng-model="link"></input><br>
            <button class="button" type="submit">Post</button>
        </form>
    </div>

  </body>
</html>

这是我的Controller.js：

var app = angular.module('myApp', []);
app.controller('bodyController',
function($scope) {
    $scope.posts = [
        { title: 'post 1', votes: 5 , comment: 'Very Nice' },
        { title: 'post 2', votes: 25, comment: 'good'      },
        { title: 'post 3', votes: 55, comment: 'Very Nice' },
        { title: 'post 4', votes: 15, comment: 'Very Nice' },
        { title: 'post 5', votes: 26, comment: 'Very Nice' }
    ];

    $scope.addPost = function(){
        if(!$scope.title || $scope.title ==='') { return; }
        $scope.posts.push({ 
            title: $scope.title, 
            link: $scope.link,
            comment: 'Very Nice',
            votes: 0 
        });
        $scope.title = '';
        $scope.link = '';
    };

    $scope.upVote = function(post){
        post.votes += 1;
    };

    $scope.downVote = function(post){
        if(post.votes <1) { return; }
        post.votes -= 1;
    };

    $scope.addComment = function(post){
        post.comment = $scope.comment;
    };
})

但是当我点击评论按钮时； 已经存在的用于调试目的的注释不会被更改，而是会被删除，我以其他方式对其进行了检查； 来自HTML的注释未定义。

Answer 1

因此，问题在于您尝试设置$ scope.comment时未定义，我对其进行了固定修复，是的，您将要在post对象中拥有一个数组，其中包含所有注释一个帖子，然后在其中重复，这将显示您的所有评论。 我在发布对象上标记了一个newComment字段，在该对象上，注释等待被推送到数组中，这是对HTML所做的更改（您还需要通过$ index进行跟踪，以确保重复的输入不会破坏您的代码！）：

        <span ng-show="post.comment" ng-repeat="comment in post.comment track by $index"> {{comment}} </span>
    <br />
    <form ng-submit="addComment(post)" class="myform">
      <input type="text" placeholder="Add a Comment..." ng-model="post.newComment" />
      <button class="button" type="submit">Comment</button>
    </form>
  </div

以及对post对象的更改：

function($scope) {
  $scope.posts = [
      { title: 'post 1', votes: 5 , comment: ['Very Nice' ]},
      { title: 'post 2', votes: 25, comment: ['good']},
      { title: 'post 3', votes: 55, comment: ['Very Nice' ]},
      { title: 'post 4', votes: 15, comment: ['Very Nice' ]},
      { title: 'post 5', votes: 26, comment: ['Very Nice'] }
  ];

以及对添加注释功能的更改：

$scope.addComment = function(post){
   post.comment.push(post.newComment);
};

这是指向有效的plnkr的链接，因此您可以查看实际运行情况！