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POMy has_many :through association of Users, Groups, and Memberships is causing trouble in some methods
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  1. POMy has_many :through association of Users, Groups, and Memberships is causing trouble in some methods
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    copied!<p>I am working with a has_many :through association: Users join Groups through a Membership. I am having trouble with some methods I created in the user model to determine if the user is a member of a group, and to allow a user to join and leave a group. Using the console, <code>memberships.find_by_group_id</code> always returns nil. I am not sure why and I think it might be the way I have set up my has_many :through associations, though after looking it over many, many times and consulting railscasts/blogs it seems ok. If you want me to post more info, like the schema.db or something, let me know</p> <pre><code>class User &lt; ActiveRecord::Base has_many :memberships, :dependent =&gt; :destroy has_many :groups, :through =&gt; :memberships . . . def member?(group) memberships.find_by_group_id(group) end def join!(group) memberships.create!(:group_id =&gt; group.id) end def leave!(group) memberships.find_by_group_id(group).destroy end . . . end class Group &lt; ActiveRecord::Base has_many :memberships has_many :members, :through =&gt; :memberships, :source =&gt; :user has_attached_file :photo, :styles =&gt; { :thumb =&gt; "100x100", :small =&gt; "200x200" } attr_accessible :name, :description, :private, :created_at, :group_id attr_accessible :photo, :photo_file_name, :photo_content_type, :photo_file_size, :photo_updated_at end class Membership &lt; ActiveRecord::Base attr_accessible :group_id belongs_to :user belongs_to :group end </code></pre> <p>Here is the membership controller:</p> <pre><code>class MembershipsController &lt; ApplicationController def create @group = Group.find(params[:membership][:group_id]) current_user.join!(@group) respond_to do |format| format.html { redirect_to @group } format.js end end def destroy @group = Membership.find(params[:id]).group current_user.leave!(@group) respond_to do |format| format.html { redirect_to @group } format.js end end def index @memberships = Membership.all end end </code></pre>
 

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