Question

My nested model form is now working, but I am having trouble displaying the data in a view. How do I display nested model data with a one-to-many relationship? Any help will be greatly appreciated.

Here’s my form and controller:

<%= form_for @account do |f| %>

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

    <%= f.fields_for :organizations do |builder| %>
        <%= builder.label :name %><br />
        <%= builder.text_field :name %><br />
        <%= builder.label :website %><br />
        <%= builder.text_field :website %><br />

        <%= builder.fields_for :locations do |lb| %>
            <%= lb.label :phone %><br />
            <%= lb.text_field :phone %><br />
            <%= lb.label :toll_free_phone %><br />
            <%= lb.text_field :toll_free_phone %><br />
            <%= lb.label :fax %><br />
            <%= lb.text_field :fax %><br />

            <%= lb.fields_for :addresses do |ab| %>
                <%= ab.label :address1 %><br />
                <%= ab.text_field :address1 %><br />
                <%= ab.label :address2 %><br />
                <%= ab.text_field :address2 %><br />
                <%= ab.label :city %><br />
                <%= ab.text_field :city %><br />
                <%= ab.label :state %><br />
                <%= ab.text_field :state %><br />
                <%= ab.label :zip %><br />
                <%= ab.text_field :zip %><br />
            <% end %>
        <% end %>
    <% end %>

<%= f.submit "Add account" %>
<% end %>

class AccountsController < ApplicationController

def show
    @account = Account.find(params[:id])
    @organization = @account.organizations
end

def new
    @account = Account.new
    organization = @account.organizations.build
    location = organization.locations.build
    location.addresses.build

    @header = "Create account"
end

def create
    @account = Account.new(params[:account])
    if @account.save
        flash[:success] = "Account added successfully"
        render 'show'
    else
        render 'new'
    end
end
end

In general, how do I reference nested model data in a view when there is one-to-many relationship? Do I need to specify the child with some type of “where clause” like method?

Here is a simple example show.html.erb where I am trying to display the Name of the Organization that I just created. It doesn’t work.

<h1><%= @organization.name %></h1>

The render ‘show’ action after creating an Account with the above form results in this error:

NoMethodError in Accounts#create

Showing C:/Documents and Settings/Corey Quillen/My     
Documents/rails_projects/shop_manager/app/views/accounts/show.html.erb where line #1     
raised:

undefined method `name' for nil:NilClass
Extracted source (around line #1):

1: <h1><%= @organization.name %></h1>
Rails.root: C:/Documents and Settings/Corey Quillen/My    
Documents/rails_projects/shop_manager

Application Trace | Framework Trace | Full Trace
app/views/accounts/show.html.erb:1:in    
`_app_views_accounts_show_html_erb__790921876_14235864__946051513'
app/controllers/accounts_controller.rb:21:in `create'
Request

Parameters:

{"utf8"=>"✓",
 "authenticity_token"=>"y59rGAhS+kqfH3v3axhlYuxvBbBxIWXg0yucCFwfBq8=",
 "account"=>{"account_type"=>"dfdf",
 "organizations_attributes"=>{"0"=>{"name"=>"dfdf",
 "website"=>"dfdf",
 "locations_attributes"=>{"0"=>{"phone"=>"dfdf",
 "toll_free_phone"=>"dfd",
 "fax"=>"",
 "addresses_attributes"=>{"0"=>{"address1"=>"",
 "address2"=>"",
 "city"=>"",
 "state"=>"",
 "zip"=>""}}}}}}},
 "commit"=>"Add account"}

Answer 1

You say @organization = @account.organizations in your show action.
Just what are you expecting @organization to contain?
Think about it. It’s going to be an array not a single organization so loop through that and get the name for each organization

Actually I think you haven’t thought your relationships through properly surely an account belongs_to an organisation. Do you really want an account to be associated with more than one organisation ?

UPDATE – Ref comment below
That is totally possible to do but you need to decide what the business logic is that determines which organisation needs to be displayed here.
If you can explain exactly how your relationships are supposed to work it shouldn’t be too difficult to show you how to apply your logic

UPDATE – How to get the primary organisation

This is simply a matter of setting up a new association on the Account model

has_one :primary_organization.
        :class_name => 'Organization',
        :conditions => ['primary = ?', true]

Then in your show action just write

@account.primary_organization.first #because anything use on a find other than the primary key will always return an array even if there is only one record.

You might also want to check that primary_organization is not empty?
Consider refactoring that has_one into a class method. May not be necessary depending on your needs
Read more here http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html