mongodb - mongoose's findByIdAndUpdate() cannot be executed?

Question

Student.findByIdAndUpdate(helper_id,{$push: {"favour": favour}});

Why can’t the function be executed when I use the above code, but can it be executed when using the following code?

Student.findByIdAndUpdate(helper_id,{$push: {"favour": favour}}).exec()

But why do I use Student.find() and Student.findOne() directly and it can be executed without .exec()?

Answer 1

Please refer to Mongoose’s documentation

1. findOneAndUpdate([query], [doc], [options], [callback])

It will only be executed if callback is passed.

2. exec is the way of writing promise, replacing callback, and has the same effect as using callback.

For reference.

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