Question

我有两种模式：

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。

我列出了来自其他地方的系统上的所有评论，因此删除用户后它就会崩溃。

有没有办法在关联中指定这种依赖？谢谢！

Answer 1

当我想实现此行为时，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，您可以通过deleteMethod指定是否要将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。

这是一个显示实际效果的jsfiddle。

Answer 2

快速而肮脏的方法是将以下内容添加到您的用户模型

destroyRecord: ->
  @get('comments').invoke('unloadRecord')
  @_super()

Answer 3

我调整了@ahmacleod的答案，以便与ember-cli 2.13.1和ember-data 2.13.0一起使用。我遇到了嵌套关系的问题，以及从数据库中删除实体后，其ID被重用的事实。这导致与余烬数据模型中的残余物发生冲突。

import Ember from 'ember';

export default Ember.Mixin.create({
    dependentRelationships: null,

    destroyRecord: function() {
        this.deleteDependentRelationships();

        return this._super()
        .then(function (model) {
            model.unloadRecord();

            return model;
        });
    },

    unloadRecord: function() {
        this.deleteDependentRelationships();

        this._super();
    },

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

        this.get('dependentRelationships').forEach(function(name) {
            self.deleteRelationship(name);
        });
    },

    deleteRelationship (name) {
        var self = this;
        self.get(name).then(function (records) {
            if (!records) {
                return;
            }

            var reset = [];
            if (!Ember.isArray(records)) {
                records = [records];
                reset = null;
            }

            records.forEach(function(record) {
                if (record) {
                    record.unloadRecord();
                }
            });

            self.set(name, reset);
        });
    },
});

最终，我必须将关系设置为[]（hasMany）或null（belongsTo）。否则我会遇到以下错误消息：

Assertion Failed: You cannot update the id index of an InternalModel once set. Attempted to update <id>.

也许这对其他人有帮助。

使用ember-data删除关联的模型

3 个答案: