Question

I’ve been tinkering with this for some time now, and can’t seem to figure this out. It’s probably something simple, but here goes:

I have a has_many :trough relationship between ‘laminate’, and ‘standards’ with a joined model ‘standardization’.

Standard.rb

class Standard < ActiveRecord::Base
attr_accessible :description, :name
has_many :standardizations
has_many :laminates, :through => :standardizations
end

Standardization.rb

class Standardization < ActiveRecord::Base
  attr_accessible :laminate_id, :standard_id
  belongs_to :laminate
  belongs_to :standard
end

Laminate.rb

class Laminate < ActiveRecord::Base
attr_accessible :name, :standard_ids
has_many :standardizations
has_many :standards, :through => :standardizations
end

The scenario is that laminates can belong to several standards, and I’ve got everything working in the new-part of the view – checkboxes and everything. My problem is when trying to display the names of the corresponding standards for a given laminate. As of now I’m able to display which standards the laminates are assigned to, but not ONLY the names of the standards.

My show.html.erb says:

<%= @laminate.standards %>

And this returns everything correct, but saying

 <%= @laminate.standards.name %>

… does not work. How on earth can I tap into the names of each individual, assigned standard?

Laminate_controller:

class LaminatesController < ApplicationController
# GET /laminates
# GET /laminates.json
def index
@laminates = Laminate.all
@standards = Standard.all

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

# GET /laminates/1
# GET /laminates/1.json
def show
@laminate = Laminate.find(params[:id])
@standard = Standard.find(params[:id])

respond_to do |format|
  format.html # show.html.erb
  format.json { render json: @laminate }
end
end

# GET /laminates/new
# GET /laminates/new.json
def new
@laminate = Laminate.new


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

# GET /laminates/1/edit
def edit
@laminate = Laminate.find(params[:id])
end

# POST /laminates
# POST /laminates.json
def create
@laminate = Laminate.new(params[:laminate])

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

# PUT /laminates/1
# PUT /laminates/1.json
def update
@laminate = Laminate.find(params[:id])

respond_to do |format|
  if @laminate.update_attributes(params[:laminate])
    format.html { redirect_to @laminate, notice: 'Laminate was successfully updated.' }
    format.json { head :no_content }
  else
    format.html { render action: "edit" }
    format.json { render json: @laminate.errors, status: :unprocessable_entity }
  end
 end
end

# DELETE /laminates/1
# DELETE /laminates/1.json
def destroy
@laminate = Laminate.find(params[:id])
@laminate.destroy

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

Answer 1

The following @laminate.standards return a list of Standards. Call name here can’t work, you should do a each loop on the list:

# replace the following:
<%= @laminate.standards.name %>
# with this code:
<% @laminate.standards.each do |standard| %>
  <%= standard.name %>
<% end %>

If you want a shorter version but less customizable:

<%= @laminate.standards.map{ |standard| standard.name }.join(', ') %>
# This will show all the standards' name with a coma-space ',' between it

# same a above but shorter:
<%= @laminate.standards.map(&:name).join(', ') %>
# this will call the 'name' method on each standard of @laminate.standards
# and join them with a coma-space
# something that would look like this:
# name1, name2, name3