push array in array field in mongodb [duplicate]

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
– sm0keman1, Commented Jun 12, 2018 at 7:14

Ashh · Accepted Answer · 2018-06-12 07:28:43Z

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, 2018 at 7:28

answered Jun 12, 2018 at 7:03

Ashh

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Comments

Emad Dehnavi · Accepted Answer · 2018-06-12 06:55:09Z

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, 2018 at 6:55

Emad Dehnavi

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1 Comment

sm0keman1 Over a year ago

Can you please provide an example?

udayakumar · Accepted Answer · 2018-06-12 07:14:53Z

0

You can Try this:

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

});

edited Jun 12, 2018 at 7:14

answered Jun 12, 2018 at 7:08

udayakumar

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4 Comments

sm0keman1 Over a year ago

Does not work, just replaces an id in the array if there is one in there instead of adding to it.

udayakumar Over a year ago

Kindly go through the above edited code. @omar

sm0keman1 Over a year ago

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

udayakumar Over a year ago

You can try the given below link or use the Emad Dehnavi concept blog.ocliw.com/2012/11/25/mongoose-add-to-an-existing-array

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