使用ember-data删除关联的模型

Question

我有两个型号:

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,它也会删除后端的所有注释,因此我应该从客户端身份映射中删除它们.

我在其他地方列出了系统上的所有注释,因此在删除用户之后它就会崩溃.

有没有办法指定这种对关联的依赖？谢谢!

Answer 1

当我想实现这种行为时,我使用mixin.我的模型定义如下:

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')
});

mixin本身:

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);
        }
    }
});

请注意,您可以指定deleteMethod是否要将DELETE请求发送到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.

这是一个表明它在行动的jsfiddle.