push array in array field in mongodb

Question

I have an array called students in a schema called Course. I created a route that allows me to add students to this array using a student's ObjectID like so:

 router.put('/addStudent/:courseID', function (req, res) {
        Course.findOneAndUpdate({courseID: req.params.courseID}, {$push: {students: req.body.students}})
        .populate('students')
        .exec(function (err, course) {

            if (err) return res.status(500).send("There was a problem adding this information to the database");
            res.status(201).send(course);
        })
    });

When I try making a PUT request to my endpoint with the following JSON body:

{
    "students":["5b1f06cafa355c2d187c344f"]
}

Nothing happens at all, it just sends me back the course with the student ID not added. How do I make it so I could add more student IDs to the array? I don't want it to replace the array with a student ID, I want to keep adding more as I make more requests.

Thanks!

That does not make any sense. Adding one ObjectID is fine, but when I try to add another one, it replaces the first ObjectID with the new one when it should be adding. — sm0keman1, Jun 12 '18 at 07:14

score 2 · Answer 1 · answered Jun 12 '18 at 06:55

2

put request will update your db and findOneAndUpdate method from mongoose is also for updating you current item, you need to use post request and save method in mongoose instead if you want create a new item.

answered Jun 12 '18 at 06:55

Emad Dehnavi

3,262
4
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44

Can you please provide an example? – sm0keman1 Jun 12 '18 at 07:02

Ashh · Accepted Answer · 2018-06-12T07:28:43.407

2

You need to use $each with $push

Course.findOneAndUpdate(
  { courseID: req.params.courseID },
  { $push: { students: { $each: req.body.students } } }
)

Course.findOneAndUpdate(
  { courseID: req.params.courseID },
  { $addToSet: { students: { $each: req.body.students } } }
)

edited Jun 12 '18 at 07:28

answered Jun 12 '18 at 07:03

Ashh

44,693
14
105
132

udayakumar · Answer 3 · 2018-06-12T07:14:53.657

0

You can Try this:

Course.findOneAndUpdate(
{ courseID: req.params.courseID }, 
{ $push: {
    students: req.body.students
}}, options, function(err, values){

});

edited Jun 12 '18 at 07:14

answered Jun 12 '18 at 07:08

udayakumar

639
1
7
16

Does not work, just replaces an id in the array if there is one in there instead of adding to it. – sm0keman1 Jun 12 '18 at 07:10
Kindly go through the above edited code. @omar – udayakumar Jun 12 '18 at 07:16
Sorry, but I don't seem to understand? The only thing I see difference is the options, but I am not sure what that is? As you can see, my current code does have the $push – sm0keman1 Jun 12 '18 at 07:23
You can try the given below link or use the Emad Dehnavi concept http://blog.ocliw.com/2012/11/25/mongoose-add-to-an-existing-array/ – udayakumar Jun 12 '18 at 07:31

push array in array field in mongodb

3 Answers3