10gen: M101 MongoDB for Developers - Homework 3.1

remove_lowest_homework_by_student.rb

require 'mongo'
#ruby
connection = Mongo::Connection.new
db = connection.db("school")
students = db.collection("students").find().sort({student_id:1})

student_id = -1
while students.has_next? do
  student = students.next
  if student_id != student["_id"]
    higher_homework = Float(0.0)
    new_scores = []
    student["scores"].each do |score|
      if score["type"].eql?("homework")
        current_score = score["score"]
        if current_score > higher_homework
          higher_homework = current_score
        end
      else
        new_scores.push score
      end
    end
    new_scores.push({"type"=> "homework", "score"=> higher_homework})
    student_id = student["_id"]
    student["scores"] = new_scores
    db.collection("students").update({"_id" => student["_id"]}, student)
  end
end