How to perform update in mongoose - node.js

Question

I am trying to update my record,but its not happening in my case and i am not sure about the case where it went rong,can any one suggest me help.Thanks
My mongoose code,
exports.updatestudent = function (req, res) {
var student = new Student(req.body);
var data = {};
var id = req.params;
var params = req.body;
var item = {
'name': params.name,
'rollnumber': params.rollnumber,
'class': params.class,
'city': params.city
};
Student.update({ _id: id },{ $set: item }, function (err, result) {
if (err) {
console.log('err');
}
if (result) {
data = { status: 'success', error_code: 0, result: result, message: 'Article updated successfully' };
res.json(data);
}
});
};
my schema,
var StudentSchema = new Schema({
name: {
type: String
},
rollnumber: {
type: String
},
class: {
type: String
},
city: {
type: String
},
status: {
type: String
},
_id: {
type: Schema.ObjectId
}
});
/**
* Hook a pre validate method to test the local password
*/
mongoose.model('student', StudentSchema, 'student');
my result in postman,
{
"status": "success",
"error_code": 0,
"result": {
"ok": 0,
"n": 0,
"nModified": 0
},
"message": "Article updated successfully"
}
I am trying to update my record,but its not happening in my case and i am not sure about the case where it went rong,can any one suggest me help.Thanks

Answer 1

It seems you forgot to specify the key.
Replace
var id = req.params;
By
var id = req.params.id;

Answer 2

Make sure that you are getting your id in var id = req.params;
And I am sure you will not get your id like this
check your req.params; values and give your correct id in the query
Update
var item = {};
if (params.name) {
item.name = params.name;
}
if (params.rollnumber) {
item.rollnumber = params.rollnumber
}
Student.update({
_id: id
}, {
$set: item
}, function(err, result) {
if (err) {
console.log('err');
}
if (result) {
data = {
status: 'success',
error_code: 0,
result: result,
message: 'Article updated successfully'
};
res.json(data);
}
});