如何在Strongloop环回中一次更新多个模型的hasandbelongstoman关系 [英] How can I update hasandbelongstomany relations for multiple models at once in strongloop loopback
问题描述
我在Strongloop Loopback API中有2个模型
I have 2 models in a Strongloop Loopback API
- 产品
- 标签
在这两个模型之间,我定义了 hasAndBelongsToMany-relation . 在我的CMS中,我想要对产品进行批量更新功能,在一次操作中,我可以选择许多产品并分配许多标签.
Between those 2 models I have defined a hasAndBelongsToMany-relation. In my CMS I want a bulk-update functionality for my products, in which I can select many Products, and assign many tags, in one action.
我如何才能轻松地将它们保存到Mysql-DB中,而不必遍历每个产品,然后遍历每个标记并链接这2个?
我检查了文档,发现添加和删除功能,但是这些功能仅将一个模型连接到一个relatedModel上.是否已经具有回送功能来执行我想要的工作?
I checked in the docs and found the add and remove functions, but those only connect one model to one relatedModel. Is there already loopback-functionality to do what I want?
推荐答案
我在服务中编写了一个自定义(更新的)函数以及一个助手:
I wrote a custom (updated) function along with a helper in a service:
/*
* Add multiple objects to a relationship
* @param {object} origin The object which hold the items
* @param {array} data The new list to be inserted
* @param {string} relation name of the relationship, for instance 'cats'
*/
exports.updateManyRelations = function(origin, data, relation){
//Destroy all old connections
return origin[relation].destroyAll().then(function(response){
//All were deleted and nothing to add
if(!data || data.length == 0){return [];}
//We have a list to go through, do the dirty work!
return addMultipleRelationsToObject(origin[relation], data, []);
}).then(function(newList){
// new items created
return newList
}, function(error){
console.log(error);
});
}
/*
* Helper function to add multiple related objects to a object in a correct promise chain
*/
var addMultipleRelationsToObject = function(objectRelation, list, newList){
if(list && list.length == 0){return Promise.resolve(newList);}
var item = list.pop();
if(!objectRelation.hasOwnProperty("add")){
return Promise.reject("Relationship is wrong for: " + objectRelation);
}
return objectRelation.add(item.id).then(function(newlyAdded){
newList.push(item);
return addMultipleRelationsToObject(objectRelation, list, newList);
});
}
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