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PORails validation count limit on has_many :through
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  1. PORails validation count limit on has_many :through
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    copied!<p>I've got the following models: Team, Member, Assignment, Role</p> <p>The Team model has_many Members. Each Member has_many roles through assignments. Role assignments are Captain and Runner. I have also installed devise and CanCan using the Member model.</p> <p>What I need to do is limit each Team to have a max of 1 captain and 5 runners.</p> <p>I found this <a href="https://stackoverflow.com/questions/9932445/rails-accepts-nested-attributes-count-validation">example</a>, and it seemed to work after some customization, but on update ('teams/1/members/4/edit'). It doesn't work on create ('teams/1/members/new'). But my other validation (validates :role_ids, :presence => true ) does work on both update and create. Any help would be appreciated.</p> <p><strong>Update:</strong> I've found this <a href="https://stackoverflow.com/questions/1270663/validate-max-amount-af-associated-objects">example</a> that would seem to be similar to my problem but I can't seem to make it work for my app.</p> <p>It seems that the root of the problem lies with how the count (or size) is performed before and during validation. </p> <p>For Example:</p> <p>When updating a record... It checks to see how many runners there are on a team and returns a count. (i.e. 5) Then when I select a role(s) to add to the member it takes the known count from the database (i.e. 5) and adds the proposed changes (i.e. 1), and then runs the validation check. (Team.find(self.team_id).members.runner.count > 5) This works fine because it returns a value of 6 and 6 > 5 so the proposed update fails without saving and an error is given.</p> <p><strong>But</strong> when I try to create a new member on the team... It checks to see how many runners there are on a team and returns a count. (i.e. 5) Then when I select a role(s) to add to the member it takes the known count from the database (i.e. 5) and then runs the validation check <strong>WITHOUT</strong> factoring in the proposed changes. This doesn't work because it returns a value of 5 known runner and 5 = 5 so the proposed update passes and the new member and role is saved to the database with no error.</p> <p>Member Model:</p> <pre><code>class Member &lt; ActiveRecord::Base devise :database_authenticatable, :registerable, :recoverable, :rememberable, :trackable, :validatable attr_accessible :password, :password_confirmation, :remember_me attr_accessible :age, :email, :first_name, :last_name, :sex, :shirt_size, :team_id, :assignments_attributes, :role_ids belongs_to :team has_many :assignments, :dependent =&gt; :destroy has_many :roles, through: :assignments accepts_nested_attributes_for :assignments scope :runner, joins(:roles).where('roles.title = ?', "Runner") scope :captain, joins(:roles).where('roles.title = ?', "Captain") validate :validate_runner_count validate :validate_captain_count validates :role_ids, :presence =&gt; true def validate_runner_count if Team.find(self.team_id).members.runner.count &gt; 5 errors.add(:role_id, 'Error - Max runner limit reached') end end def validate_captain_count if Team.find(self.team_id).members.captain.count &gt; 1 errors.add(:role_id, 'Error - Max captain limit reached') end end def has_role?(role_sym) roles.any? { |r| r.title.underscore.to_sym == role_sym } end end </code></pre> <p>Member Controller:</p> <pre><code>class MembersController &lt; ApplicationController load_and_authorize_resource :team load_and_authorize_resource :member, :through =&gt; :team before_filter :get_team before_filter :initialize_check_boxes, :only =&gt; [:create, :update] def get_team @team = Team.find(params[:team_id]) end def index respond_to do |format| format.html # index.html.erb format.json { render json: @members } end end def show respond_to do |format| format.html # show.html.erb format.json { render json: @member } end end def new respond_to do |format| format.html # new.html.erb format.json { render json: @member } end end def edit end def create respond_to do |format| if @member.save format.html { redirect_to [@team, @member], notice: 'Member was successfully created.' } format.json { render json: [@team, @member], status: :created, location: [@team, @member] } else format.html { render action: "new" } format.json { render json: @member.errors, status: :unprocessable_entity } end end end def update respond_to do |format| if @member.update_attributes(params[:member]) format.html { redirect_to [@team, @member], notice: 'Member was successfully updated.' } format.json { head :no_content } else format.html { render action: "edit" } format.json { render json: @member.errors, status: :unprocessable_entity } end end end def destroy @member.destroy respond_to do |format| format.html { redirect_to team_members_url } format.json { head :no_content } end end # Allow empty checkboxes # http://railscasts.com/episodes/17-habtm-checkboxes def initialize_check_boxes params[:member][:role_ids] ||= [] end end </code></pre> <p>_Form Partial</p> <pre><code>&lt;%= form_for [@team, @member], :html =&gt; { :class =&gt; 'form-horizontal' } do |f| %&gt; #... # testing the count... &lt;ul&gt; &lt;li&gt;Captain - &lt;%= Team.find(@member.team_id).members.captain.size %&gt;&lt;/li&gt; &lt;li&gt;Runner - &lt;%= Team.find(@member.team_id).members.runner.size %&gt;&lt;/li&gt; &lt;li&gt;Driver - &lt;%= Team.find(@member.team_id).members.driver.size %&gt;&lt;/li&gt; &lt;/ul&gt; &lt;div class="control-group"&gt; &lt;div class="controls"&gt; &lt;%= f.fields_for :roles do %&gt; &lt;%= hidden_field_tag "member[role_ids][]", nil %&gt; &lt;% Role.all.each do |role| %&gt; &lt;%= check_box_tag "member[role_ids][]", role.id, @member.role_ids.include?(role.id), id: dom_id(role) %&gt; &lt;%= label_tag dom_id(role), role.title %&gt; &lt;% end %&gt; &lt;% end %&gt; &lt;/div&gt; &lt;/div&gt; #... &lt;% end %&gt; </code></pre>
 

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