Getting first day of week from week number in mongodb

Question

I have collection containing date field. I\'m Grouping records by week and other related fields.

This is my aggregation query:

Answer 1

With MongoDB 3.6

{ 
  '$project' : {
    'firstDateOfWeek': {
        '$dateFromString': {
            'dateString': {
                '$concat': [
                    {
                        '$toString': '$_id.year'
                    }, 
                    '-', 
                    {
                        '$toString': '$_id.week'
                    }
                ]
             },
             'format': "%G-%V"
         }
     }
  }
}