1 # == Schema Information
2 # Schema version: 20100210063013
4 # Table name: problem_groups
6 # id :integer not null, primary key
7 # label :string(255) not null
9 # problem_group_problem_id :integer
10 # created_at :datetime
11 # updated_at :datetime
12 # lock_version :integer default(0), not null
15 class ProblemGroup < ActiveRecord::Base
16 has_many :problem_groups_problems, :class_name => 'ProblemGroupsProblems', :dependent => :destroy
17 has_many :problems, :through => :problem_groups_problems
18 has_many :learning_results
21 validates_presence_of :label
23 validate :must_have_problems
25 def must_have_problems
26 self.errors.add_to_base("Must have at least one problem.") unless self.problems.size > 0