删除与ember-data相关联的模型

问题描述

我有两个模型：

  App.User = DS.Model.create（{
 comments：DS .hasMany（'App.Comment'）
}）; 
 
 App.Comment = DS.Model.create（{
 user：DS.belongsTo（'App.User'）
}）; 
  

当用户被删除时，它也会删除其后端的所有评论，所以我应该删除他们从客户端身份图。

我从另一个地方列出了系统上的所有评论，所以在删除用户之后，它将会崩溃。

有没有办法在关联中指定这种依赖关系？谢谢！

解决方案

当我想实现这个行为时，我使用mixin。我的模型定义如下：

  App.Post = DS.Model.extend（App.DeletesDependentRelationships，{
依赖关系：['comments']，
 
评论：DS.hasMany（'App.Comment'），
作者：DS.belongsTo（'App.User'）
} ）; 
 
 App.User = DS.Model.extend（）; 
 
 App.Comment = DS.Model.extend（{
 post：DS.belongsTo（'App.Post'）
}）; 
  

mixin本身：

  App.DeletesDependentRelationships = Ember.Mixin.create（{
 
 //要删除的关系名称数组
 dependRelationships：null，
 
 //设置为删除或卸载，具体取决于您是否要
 //实际发送删除到服务器
 deleteMethod：'unload'，
 
 deleteRecord：function（）{
 var transaction = this.get（'store'）。transaction（）; 
 transaction.add（this）; 
 this.deleteDependentRelationships（transaction）; 
 this._super（）; 
}，
 
 deleteDependentRelationships：function（transaction）{
 var self = this; 
 var klass = Ember.get this.constructor.toString（））; 
 var fields = Ember.get（klass，'fields'）; 
 
 this.get（'dependentRelationships'）forEach（function（name） {
 var relatio nshipType = fields.get（name）; 
 switch（relationshipType）{
 case'belongsTo'：return self.deleteBelongsToRelationship（name，transaction）; 
 case'hasMany'：return self.deleteHasManyRelationship（name，transaction）; 
} 
}）; 
}，
 
 deleteBelongsToRelationship：function（name，transaction）{
 var record = this.get（name）; 
 if（record）this.deleteOrUnloadRecord（record，transaction）; 
}，
 
 deleteHasManyRelationship：function（key，transaction）{
 var self = this; 
 
 //从RecordArray中删除不适用于forEach，
 //所以首先转换为正常数组
 this.get（key）.toArray（）。 forEach（function（record）{
 self.deleteOrUnloadRecord（record，transaction）; 
}）; 
}，
 
 deleteOrUnloadRecord：function（record，transaction）{
 var deleteMethod = this.get（'deleteMethod'）; 
 if（deleteMethod ==='delete'）{
 transaction.add（record）; 
 record.deleteRecord（）; 
} 
 else if（deleteMethod ==='unload'）{
 var store = this.get（'store'）; 
 store.unloadRecord（record）; 
} 
} 
}）; 
  

请注意，您可以通过 deleteMethod 指定或者您不想将 DELETE 请求发送到您的API。如果您的后端配置为自动删除相关记录，那么您将需要使用默认值。

这是一个，表示它在行动。

I have two models:

App.User = DS.Model.create({
  comments: DS.hasMany('App.Comment')
});

App.Comment = DS.Model.create({
  user: DS.belongsTo('App.User')
});

When a user is deleted, it also will delete all its comments on the backend, so I should delete them from the client-side identity map.

I'm listing all the comments on the system from another place, so after deleting a user it would just crash.

Is there any way to specify this kind of dependency on the association? Thanks!

解决方案

I use a mixin when I want to implement this behaviour. My models are defined as follows:

App.Post = DS.Model.extend(App.DeletesDependentRelationships, {
    dependentRelationships: ['comments'],

    comments: DS.hasMany('App.Comment'),
    author: DS.belongsTo('App.User')
});

App.User = DS.Model.extend();

App.Comment = DS.Model.extend({
    post: DS.belongsTo('App.Post')
});

The mixin itself:

App.DeletesDependentRelationships = Ember.Mixin.create({

    // an array of relationship names to delete
    dependentRelationships: null,

    // set to 'delete' or 'unload' depending on whether or not you want
    // to actually send the deletions to the server
    deleteMethod: 'unload',

    deleteRecord: function() {
        var transaction = this.get('store').transaction();
        transaction.add(this);
        this.deleteDependentRelationships(transaction);
        this._super();
    },

    deleteDependentRelationships: function(transaction) {
        var self = this;
        var klass = Ember.get(this.constructor.toString());
        var fields = Ember.get(klass, 'fields');

        this.get('dependentRelationships').forEach(function(name) {
            var relationshipType = fields.get(name);
            switch(relationshipType) {
                case 'belongsTo': return self.deleteBelongsToRelationship(name, transaction);
                case 'hasMany': return self.deleteHasManyRelationship(name, transaction);
            }
        });
    },

    deleteBelongsToRelationship: function(name, transaction) {
        var record = this.get(name);
        if (record) this.deleteOrUnloadRecord(record, transaction);
    },

    deleteHasManyRelationship: function(key, transaction) {
        var self = this;

        // deleting from a RecordArray doesn't play well with forEach,
        // so convert to a normal array first
        this.get(key).toArray().forEach(function(record) {
            self.deleteOrUnloadRecord(record, transaction);
        });
    },

    deleteOrUnloadRecord: function(record, transaction) {
        var deleteMethod = this.get('deleteMethod');
        if (deleteMethod === 'delete') {
            transaction.add(record);
            record.deleteRecord();
        }
        else if (deleteMethod === 'unload') {
            var store = this.get('store');
            store.unloadRecord(record);
        }
    }
});

Note that you can specify via deleteMethod whether or not you want to send the DELETE requests to your API. If your back-end is configured to delete dependent records automatically, then you will want to use the default.

Here's a jsfiddle that shows it in action.

这篇关于删除与ember-data相关联的模型的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！