canvas-lms/app/models/assessment_question_bank.rb

#
# Copyright (C) 2011 Instructure, Inc.
#
# This file is part of Canvas.
#
# Canvas is free software: you can redistribute it and/or modify it under
# the terms of the GNU Affero General Public License as published by the Free
# Software Foundation, version 3 of the License.
#
# Canvas is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
# A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
# details.
#
# You should have received a copy of the GNU Affero General Public License along
# with this program. If not, see <http://www.gnu.org/licenses/>.
#

class AssessmentQuestionBank < ActiveRecord::Base
  include Workflow
  attr_accessible :context, :title, :user, :outcomes
  belongs_to :context, :polymorphic => true
  has_many :assessment_questions, :order => 'name, position, created_at'
  has_many :assessment_question_bank_users
  has_many :learning_outcome_tags, :as => :content, :class_name => 'ContentTag', :conditions => ['content_tags.tag_type = ? AND content_tags.workflow_state != ?', 'learning_outcome', 'deleted'], :include => :learning_outcome
  has_many :quiz_groups
  before_save :infer_defaults
  validates_length_of :title, :maximum => maximum_string_length, :allow_nil => true
  
  workflow do
    state :active
    state :deleted
  end
  
  set_policy do
    given{|user, session| cached_context_grants_right?(user, session, :manage_assignments) }
    can :read and can :create and can :update and can :delete and can :manage
    
    given{|user, session| user && self.assessment_question_bank_users.exists?(:user_id => user.id) }
    can :read
  end

  def self.default_imported_title
    t :default_imported_title, 'Imported Questions'
  end

  def self.default_unfiled_title
    t :default_unfiled_title, 'Unfiled Questions'
  end

  def self.unfiled_for_context(context)
    context.assessment_question_banks.find_by_title_and_workflow_state(default_unfiled_title, 'active') || context.assessment_question_banks.create(:title => default_unfiled_title) rescue nil
  end
  
  def cached_context_short_name
    @cached_context_name ||= Rails.cache.fetch(['short_name_lookup', self.context_code].cache_key) do
      self.context.short_name rescue ""
    end
  end
  
  def assessment_question_count
    self.assessment_questions.active.count
  end
  
  def context_code
    "#{self.context_type.underscore}_#{self.context_id}"
  end
  
  def infer_defaults
    self.title = t(:default_title, "No Name - %{course}", :course => self.context.name) if self.title.blank?
  end
  
  def bookmark_for(user, do_bookmark=true)
    if do_bookmark
      question_bank_user = self.assessment_question_bank_users.find_by_user_id(user.id)
      question_bank_user ||= self.assessment_question_bank_users.create(:user => user)
    else
      AssessmentQuestionBankUser.delete_all({:user_id => user.id, :assessment_question_bank_id => self.id})
    end
  end
  
  def bookmarked_for?(user)
    user && self.assessment_question_bank_users.map(&:user_id).include?(user.id)
  end
  
  def select_for_submission(count, exclude_ids=[])
    ids = AssessmentQuestion.connection.select_all("SELECT id FROM assessment_questions WHERE workflow_state != 'deleted' AND assessment_question_bank_id = #{self.id}")
    ids = (ids.map{|i|i['id'].to_i} - exclude_ids).sort_by{rand}[0...count]
    ids.empty? ? [] : AssessmentQuestion.find_all_by_id(ids)
  end
  
  def outcomes=(hash)
    raise "Can't set outcomes on unsaved bank" if new_record?
    hash = {} if hash.blank?
    ids = []
    hash.each do |key, val|
      ids.push(key) if !key.blank? && key.to_i != 0
    end
    ids.uniq!
    tags = self.learning_outcome_tags
    tag_outcome_ids = tags.map(&:learning_outcome_id).compact.uniq
    outcomes = LearningOutcome.available_in_context(self.context, tag_outcome_ids)
    missing_ids = ids.select{|id| !tag_outcome_ids.include?(id) }
    tags.each do |tag|
      if hash[tag.learning_outcome_id.to_s]
        tag.update_attribute(:mastery_score, hash[tag.learning_outcome_id.to_s].to_f)
      end
    end
    tags_to_delete = tags.select{|t| !ids.include?(t.learning_outcome_id) }
    missing_ids.each do |id|
      lot = self.learning_outcome_tags.build(:context => self.context, :tag_type => 'learning_outcome', :mastery_score => hash[id].to_f)
      lot.learning_outcome_id = id.to_i
      lot.save!
    end
    tags_to_delete.each{|t| t.destroy }
    true
  end
  
  alias_method :destroy!, :destroy
  def destroy
    self.workflow_state = 'deleted'
    self.save
  end

  # clear out all questions so that the bank can be replaced. this is currently
  # used by the respondus API.
  def clear_for_replacement
    assessment_questions.destroy_all
    quiz_groups.destroy_all
  end
  
  named_scope :active, lambda {
    {:conditions => ['assessment_question_banks.workflow_state != ?', 'deleted'] }
  }
end