find by param node.js

Question

I'm trying use find function to get data from my DB in mLab. I wrote this code, but I am getting an empty string. My schema had id, name, course and grade. It works for me when I want the file of the name but not for id. I guess it's because of the extra _id files that the mLab adds. How do I fix it to get back the JSON that fits the id (let's say id=1)?

     app.get('/getStudentById/:id', function(req, res) { //else if url path is getStudGrade with id param
         Stud.find({id:req.params.id}, function(err, user){
            if(err) throw err;
            res.json(user);
           mongoose.disconnect();
         });
     })

---

new edit

I have changed the filed 'id' to 'idStudent' in my DB and now it working.

Stud.find({ idStudent: req.params.id)}...)

but why?

Answer 1

So, assuming req.params.id actually has a value and /getAll shows that all your records have an id field set, the only thing that jumps out to me is the fact that your comparing a string to a Number ie req.params.id will be a string after deserialization but your schema dictates that the id field is numeric.

I am not sure if mongoose uses coercive comparison ie == over === (I doubt it), so in order to be more accurate you should parse your string to Number then do the comparison eg

Stud.find({ id: parseInt(req.params.id)}, ...)

Answer 2

查询子句中的函数可能不起作用，因此将其转换为Number即可：

Stud.find({ id: 1*req.params.id}, ...)