在响应node.js猫鼬中仅发送对象的一个​​属性

Question

想发送我的子类别的标题作为回应。尝试过这种方法但一无所获，谁能告诉我该怎么做。

exports.Subcategory= (req, res) => {
    var sub = {}
    Subcategory.findById(req.params.id, function (err, subcategory)     {
        console.log(typeof(subcategory))
        res.send({ sub: subcategory.Tittle})
    });
};

这是我的收藏

"_id": "5c398e8fd301362158004fd1",
"Description": "value",
"Slug": "value",
"category_id": "5c398ac7d301362158004fcd",
"UserId": "5c3796cad3013606e8001f9c",
"updated_at": "2019-01-12T06:51:59.000Z",
"created_at": "2019-01-12T06:51:59.000Z"

并且要从此“ category_id”中查找“ category”集合中的类别信息并通过响应进行发送

Answer 1

您必须在猫鼬中使用填充，像这样尝试 在您的SubCategory模式中

const SubCategory = new Schema({category_id:{type:String, ref:'Category'}); // to make the relation with Category model


exports.Subcategory= (req, res) => {
    var sub = {}
    Subcategory.find({_id:req.params.id}).populate('category_id').exec((err,data)=>{
       res.send({ data:data});
    });