mongodb move documents from one collection to another collection

Question

How can documents be moved from one collection to another collection in MongoDB?? For example: I have lot of documents in

Answer 1

In my case for each didn't work. So I had to make some changes.

var kittySchema = new mongoose.Schema({
name: String
});

var Kitten = mongoose.model('Kitten', kittySchema);

var catSchema = new mongoose.Schema({
name: String
});

var Cat = mongoose.model('Cat', catSchema);

This is Model for both the collection

`function Recursion(){
Kitten.findOne().lean().exec(function(error, results){
    if(!error){
        var objectResponse = results;
        var RequiredId = objectResponse._id;
        delete objectResponse._id;
        var swap = new Cat(objectResponse);
        swap.save(function (err) {
           if (err) {
               return err;
           }
           else {
               console.log("SUCCESSFULL");
               Kitten.deleteOne({ _id: RequiredId }, function(err) {
                if (!err) {
                        console.log('notification!');
                }
                else {
                        return err;
                }
            });
               Recursion();
           }
        });
    }
    if (err) {
        console.log("No object found");
        // return err;
    }
})
}`