Mongoose从嵌套数组中移除整个对象

我正在使用mongoose4.11.3。 我试图从嵌套数组中删除一个对象。 这是我的模式

var VendorSchema = new Schema({ _id: { type: Schema.Types.ObjectId, ref: "User" }, services: [{ _id:false, service_category: { type: Schema.Types.ObjectId, ref: "ServiceCategory" }, sub_services :[{ _id:false, service : { type: Schema.Types.ObjectId, ref: "Service" }, service_description:{ type: String, default: null } }] }] }); 

我需要删除sub_services数组中的对象。 所以这就是我所做的

 Vendor.update({'services.service_category': req.body.category_id}, {$pull :{'services.$.sub_services': { "service": req.body.service_id }}},function(err,obj){ if(err){ return res.json({success: false, msg: err}); } else{ return res.json({success: true, msg:"removed" }); } }); 

上面的代码执行没有任何错误。但是在删除之后，整个对象还没有被删除

 { "_id": "598b28271a0b551af8fbf849", "services": [ { "service_category": { "_id": "598b27f21a0b551af8fbf848", "category_name": "Venue" }, "sub_services": [ { "service": { "_id": "598b29611a0b551af8fbf84a", "service": "Conference hall" }, "service_description": "This is test description for a service" }, { "service": { "_id": "598c66f5003db00aec18696e", "service": "Auditorium" }, "service_description": "This is test description for a service auditorium" }, { "service_description": null } ] } ] } 

删除后，某些属性保留为空值。 但是我想通过一个objectID（service ref）去除整个对象。 谁可以帮我这个事