Question

I have a Users model that can have many Groups through Memberships. If a user is a member of a group, and you submit the form with no changes, it will attempt to update the membership table and put group_id to 0 as per below.

My model for User accepts_nested_attributes_for Memberships

In my User controller…

    def edit
      @user = User.find(params[:id])
      @groups = Group.current
      @membership = @user.memberships.build
    end

    def update
      @user = User.find(params[:id])
      @groups = Group.current

      if params[:memberships][:group_id] != ""
        @membership = @user.memberships.build(:group_id => params[:memberships][:group_id])
      end

      respond_to do |format|
        if @user.update_attributes(params[:user])
          format.html { redirect_to admin_users_url, notice: 'User was successfully updated.' }
          format.json { head :no_content }
        else
          #if params[:memberships][:group_id] == ""
          #  @membership = @user.memberships.build
          #end
          format.html { render action: "edit" }
          format.json { render json: @user.errors, status: :unprocessable_entity }
        end
      end
    end

In my user form…

<%= form_for([:admin,@user]) do |f| %>
---
  <div class="field">
    <%= f.label :email %><br />
    <%= f.text_field :email %>
  </div>
  <div class="field">
    <%= f.label :password %><br />
    <%= f.password_field :password %>
  </div>
  <div class="field">
    <%= f.label :password_confirmation %><br />
    <%= f.password_field :password_confirmation %>
  </div>
    <%= f.fields_for :memberships do |builder| %>
  <div class="field">
    <% if builder.object.new_record? %>
        <%= builder.label :group_id %><br />
        <%= collection_select(:memberships, :group_id, @groups, 'id', 'name',    {:include_blank => true}) %>
    <% else %>
        <%= builder.label :group_id %><br />
        <%= builder.text_field :group_id, :value =>    Group.find(Membership.find(builder.object).group_id).name, :readonly => true %> <%= link_to 'Remove', [:admin,@user,Membership.find(builder.object)], :confirm => 'Are you sure?', :method => :delete %>
    <% end %>
  </div>
    <% end %>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

The form is submitting the data

Parameters: {"utf8"=>"✓", 
"authenticity_token"=>"6Vp9sgMySzRm2CU9Dko+Jpf6yaBkXjKkt10UDbb8dcw=", 
"user"=>{"email"=>"[e-mail]", 
"password"=>"[FILTERED]", "password_confirmation"=>"[FILTERED]", 
"memberships_attributes"=>{"0"=>{"group_id"=>"Cricket Maidstone June 2012",
"id"=>"18"}}}, 
"memberships"=>{"group_id"=>""}, 
"commit"=>"Update User", "id"=>"25"}

All I want to do is for the form to check and if there is nothing in the collection_select field to not update the memberships table, but still update any changes to email/password. Can anyone see a way to do this?

Answer 1

In your model, declare a parallel field with attr_accessor:

attr_accessor :memberships_attributes_input

def memberships_attributes_input
    memberships
end

def memberships_attributes_input=value
    # Update memeberships if required evaluating 'value'.
end

Use this new field in your form instead “memberships”.