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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