angularJs TypeError:将圆形结构转换为JSON [英] angularJs TypeError: Converting circular structure to JSON

问题描述

我有一个像这样的小型AngularJs应用程序:

I have a small AngularJs app like so:

 // html

 <div ng-repeat="project in projects">
     <h3>{{ project.id }}</h3>
     <h3>{{ project.title }}</h3>
      <div ng-repeat="task in project.tasks">
          <h4>{{ task.id }}. {{ task.title }}</h4>
          <button class="btn btn-default" ng-click="showEditTask=true">Edit Task</button>
          <div class="box row animate-show-hide" ng-show="showEditTask">

              <h2>Create a New Task</h2>
              <form name="newTaskForm" class="form-horizontal">
                  Title: <br />
                  <input ng-model="new_task.title" type="text" id="title" name="title" class="form-control" placeholder="Title" required /><br />

                  Project: <br />
                  <select ng-model="new_task.project" ng-options="project.title for project in projects" class="form-control"></select><br>
              </form>

                  <button class="btn btn-success" ng-click="createTask(new_task)" ng-disabled="!newTaskForm.title.$valid">create</button>
          </div>
      </div>
 </div>


  // app.js

  concernsApp.factory('ConcernService', function ($http, $q) {

    ...

    update: function (obj_url, obj) {
        var defer = $q.defer();
        console.log(obj)
        $http({method: 'POST',
            url: api_url + obj_url + obj.id + '/',
            data: obj}).
            success(function (data, status, headers, config) {
                defer.resolve(data);
            }).error(function (data, status, headers, config) {
                defer.reject(status);
            });
        return defer.promise;
     },
   });


 concernsApp.controller('ProjectsCtrl', function ($scope, $http, ConcernService) {

    $scope.updateTask = function(obj) {
        ConcernService.update('tasks/', obj).then(function(){
        ...
    }
 });

问题在于更新任务并保持父项目不变.如果我更改父项目，则一切正常.如果我使用相同的父项目，则会得到:

The problem is with updating a task and leaving the parent project as is. If I change the parent project, it all works fine. If I use the same parent project then I get:

TypeError: Converting circular structure to JSON

我不太确定这里发生了什么.

I'm not entirely sure what is happening here.

所以，我可以解决这样的问题:

So, I can solve the problem like this:

$scope.updateTask = function(obj) {
    parentProject = {'id': obj.project.id};
    obj.project = parentProject;
    ConcernService.update('tasks/', obj).then(function(){
        ...
    });
}; 

这可以工作，因为我实际上只需要task.project.id来更新对象.我认为问题是由于该任务引用了一个父项目，而该子项目又引用了子任务等.我对此并不十分确定.

This works as I only actually need the task.project.id to update the object. I think the problem is due to that fact that the task references a parent project, which in turn references the child tasks etc. I'm not entirely sure about this tough.

但是，此解决方案对我来说似乎有点棘手，我希望看到更好的解决方案.

However, this solution seems a little hacky to me and I would love to see a better solution.

推荐答案

您尝试在某个地方将对象转换为JSON，并且其中包含循环引用，这意味着:

Somewhere you are trying to convert an object to JSON, and that has a circular reference in it, meaning something like this:

var myObj = new Object();
myObject.reference = myObj;

现在尝试将其转换为JSON将会失败，并产生您的错误.

Now trying to convert this to JSON will fail, and produce your error.

看看您编辑过的帖子，您的数据结构是这样的:

Looking at the your edited post, your data structure is something like this:

task.parent -> {project}

project.tasks -> [{task1},{task2},...]

这应该为项目有多个任务"和任务属于一个项目"之间的关系建模.

This is supposed to model the relation "project has multiple tasks" and "task belongs to a project".

由于循环引用，现在显然不能将其转换为json格式.

Now this can obviously not be converted to json format, due to circular referencing.

对于数据结构，为什么不选择:

For the data structure, why not go with:

project = { "id": 42,
            "tasks": [123, 124, 127, ... ],
          }

task = { "id": 123,
         "idproject": 42,
            ...
       }

每当必须在angularjs应用程序中显示关系时，都可以使用过滤器.如果要显示属于项目的内容，请按projectid过滤所有任务.

Whenever you have to show the relationships in your angularjs app, you could go with filters. If you want to show what belongs to a project, filter all tasks by projectid.

或者通过请求后端针对特定项目ID承担的任务，从运行中的后端仅检索所需的数据.

Or retrieve only the required data from your backend on the fly, by requesting what tasks the backend has for a specific project id.

那是做到这一点的一种方法.当然，让后端接受适当的更新请求也可以正常工作，例如更新项目需要项目ID和一组任务ID.

That is one way to do it. Of course, having the backend accept appropriate update requests would be working just as well, e.g. updating a project would require the project id, and an array of task ids.

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