elections_controller.rb

class ElectionsController < ApplicationController
  def index
    @elections = Election.all

    respond_to do |format|
      format.html # index.html.erb
      format.json { render json: @elections }
    end
  end

  def new
    @election = Election.new

    respond_to do |format|
      format.html #new.html.erb
      format.json {render :json => @election}
    end
  end

  def show
    @election = Election.find(params[:id])

    respond_to do |format|
      format.html #show.html.erb
      format.json {render :json =>@election}
    end
  end
  def create
    @election = Election.new(params[:election])

    respond_to do |format|
      if @election.save
        format.html { redirect_to @election, notice: 'Election was successfully created.' }
        format.json { render json: @election, status: :created, location: @election }
      else
        format.html { render action: "new" }
        format.json { render json: @election.errors, status: :unprocessable_entity }
      end
    end
  end

  def edit
    @election = Election.find(params[:id])
  end

  def update
    @election = Election.find(params[:id])
    params[:election][:candidates] = params[:election].fetch(:candidate, []).map { |id| Candidate.find(id) }
    
    respond_to do |format|
      if @election.update_attributes(params[:election])
        format.html {redirect_to(@election,
                                 :notice => 'Election was successfully updated.')}
        format.json {head :no_content}
      else
        format.html {render :action=>'edit'}
        format.json {render :json => @election.errors,
                            :status => :unprocessable_entity}
      end
    end

    def destroy
      @election = Election.find(params[:id])
      @election.destroy

      respond_to do |format|
        format.html {redirect_to elections_url}
        format.json {head :no_content}
      end
    end
  end
end

Error

NoMethodError in ElectionsController#update

undefined method `each' for "#<Candidate:0x000000046fb310>":String

Rails.root: /home/jonblack/projects/mcet
Application Trace | Framework Trace | Full Trace

app/controllers/elections_controller.rb:50:in `block in update'
app/controllers/elections_controller.rb:49:in `update'

Request

Parameters:

{"utf8"=>"✓",
 "_method"=>"put",
 "authenticity_token"=>"G+rEHO99U7mGhETIyphwXMCuYnmXPpH3GC8fE+KcfhM=",
 "election"=>{"candidates"=>"#<Candidate:0x000000046fb310>",
 "location"=>"Haiti",
 "year"=>"2010",
 "round1_votes"=>"",
 "round2_votes"=>"",
 "round3_votes"=>"",
 "position"=>"President"},
 "commit"=>"Update Election",
 "id"=>"1"}

Show session dump

Show env dump
Response

Headers:

None

form.erb

<%= form_for(@election) do |f| %>
    <% if @election.errors.any? %>
        <div id="error_explanation">
          <h2><%= pluralize(@election.errors.count, "error") %> prohibited this user
            from being saved:</h2>

          <ul>
            <% @election.errors.full_messages.each do |msg| %>
                <li><%= msg %></li>
            <% end %>
          </ul>
        </div>
    <% end %>

    <div class="field">
      <h2>Candidates in the Race</h2>

      <%=  f.collection_select("candidates[]", Candidate.all, :id, :first_name) %>

      <h2>Election Information</h2>
      <%= f.label :location %><br/>
      <%= f.text_field :location %>

      <%= f.label :year %><br/>
      <%= f.text_field :year %>

      <%= f.label :round1_votes %><br/>
      <%= f.text_field :round1_votes %>

      <%= f.label :round2_votes %><br/>
      <%= f.text_field :round2_votes %>

      <%= f.label :round3_votes %><br/>
      <%= f.text_field :round3_votes %>

      <%= f.label :position %><br/>
      <%= f.text_field :position %>

    </div>
    <div class="actions">
      <%= f.submit %>
    </div>
<% end %>

models.rb

class Election < ActiveRecord::Base
  attr_accessible :location, :position, :round1_votes, :round2_votes, :round3_votes, :year, :candidates
  has_many :candidates
  accepts_nested_attributes_for :candidates
end


class Candidate < ActiveRecord::Base
  attr_accessible :birthday, :criminal_history, :description, :education, :first_name, :last_name, :location, :party, :position, :professional_history, :election_id
  belongs_to :election
  def name_with_initial
    "#{first_name.first}. #{last_name}"
  end
end

select html

<select id="election_candidates" name="election[candidates]"><option value="#&lt;Candidate:0x00000004605f28&gt;">#&lt;Candidate:0x00000004605f28&gt;</option>
<option value="#&lt;Candidate:0x000000046fb310&gt;">#&lt;Candidate:0x000000046fb310&gt;</option>
<option value="#&lt;Candidate:0x000000046facd0&gt;">#&lt;Candidate:0x000000046facd0&gt;</option>
<option value="#&lt;Candidate:0x000000046fa730&gt;">#&lt;Candidate:0x000000046fa730&gt;</option></select>