How to update MongoDB documents with arrays of sub-documents
There are a few way to do this I'll answer point by point
Retrieve the scores for all students, or for a specific student (retrieve specific element in the scores array)
Class.findOne({ name: 'Grade 5 - Section A'}) .populate('scores.studentId') .exec(function(err, class) { if (err) throw err; //now class.scores.studentId becomes ObjectStudent //hence you have all scores for all students});Add/ update/ delete a specific student's score, for a specific subject (in case of update or delete, retrieve a specific element in the scores[n].performance array; for add, append to the same array.
Class.findOneAndUpdate({name: 'Grade 5 - Section A' ,'scores.studentId': ObjectId('5776bd36ffc8227405d364d2') , 'scores.performance.subjectId' : ObjectId('577694ecbf6f3a781759c54a')} , {$set: {scores.performance. score: 50}} , function(err, data) { if (err) throw err });I hope that helps