CODEWITHSUNDEEP
ruby-on-railsmongodbmongoid
Murtza
Murtza

Reputation: 1416

How to query embedded document in rails & mongoid

I have a class model, a student model and an attendance model. Attendance is embedded in Student to improve the performance.

I want to show number of all students in Class, number of present students, number of absent student & percentage of attendance. I am a newbie in Mongodb and i would appreciate any help. Thanks you for your time.

class Klass
  include Mongoid::Document
  include Mongoid::Timestamps

  has_and_belongs_to_many :students

  field :name, type: String
end

class Student
  include Mongoid::Document
  include Mongoid::Timestamps

  has_and_belongs_to_many :klasses
  embeds_many :attendances

  field :name, type: String
end

class Attendance
  include Mongoid::Document
  include Mongoid::Timestamps

  embedded_in :student

  field :status, type: Integer # 1 = Present, 2 = Absent
  field :klass_id, type: BSON::ObjectId
end

Upvotes: 0

Views: 1369

Answers (2)

Sharvy Ahmed
Sharvy Ahmed

Reputation: 7405

You can try these:

@class = Klass.where(name: 'something').first

@total_students = @class.students.count

@present_students = @class.students.where('attendances.status' => '1').count

@absent_students = @class.students.where('attendances.status' => '2').count

@p_s_today = @class.students.where('attendances.status' => '1', 'attendances.created_at' => {'$gte' => Date.today} ).count

@a_s_today = @class.students.where('attendances.status' => '2', 'attendances.created_at' => {'$gte' => Date.today} ).count

Upvotes: 1

Murtza
Murtza

Reputation: 1416

I have solved my problem by following technique.

@students_present_today = @class.students.where({ attendances: { '$elemMatch' => {status: 1, :created_at.gte => Date.today} } }).count
@students_absent_today = @class.students.where({ attendances: { '$elemMatch' => {status: 2, :created_at.gte => Date.today} } }).count

Upvotes: 1

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