Question

I’ve got a simple nested form working in my rails3 application. I’m trying to work out how to save a value from the parent model into the child when saving.

class Radcheck < ActiveRecord::Base
  set_table_name 'radcheck'
  attr_accessible :attribute_name, :username, :value, :op
  belongs_to :raduser  
end

class Raduser < ActiveRecord::Base
  has_many :radcheck, :dependent => :destroy
  accepts_nested_attributes_for :radcheck  
end

And my form:

<%= form_for @raduser do |f| %>  
  <p>  
    <%= f.label :username %><br />  
    <%= f.text_field :username %>  
  </p>  
  <%= f.fields_for :radcheck do |builder| %>  
  <li>  
    <%= builder.label :attribute_name %><%= builder.text_field :attribute_name %>  

  </li>  
  <% end %>  
  <p><%= f.submit "Submit" %></p>  
<% end %>

What I want to do is save the Raduser.username value in to the radcheck table on save. For each record.

I’ve tried putting something in the controller but that wasn’t really working for us.

— Update —

In my radcheck controller, I’ve tried this (as a test) but the values don’t save.

def create
      @radcheck = Radcheck.new(params[:radcheck])
      @radcheck.username = '123'
      respond_to do |format|
        if @radcheck.save

          format.html { redirect_to @radcheck, notice: 'Radcheck was successfully created.' }
          format.json { render json: @radcheck, status: :created, radcheck: @radcheck }
        else
          format.html { render action: "new" }
          format.json { render json: @radcheck.errors, status: :unprocessable_entity }
        end
      end
    end

Have also tried in radusers but that gave error.

Answer 1

It looks like the controller code you posted is for the Radcheck controller, correct? If so, the form you have also posted will be using the create action of the RaduserController class, not the one from RadcheckController. This would explain why you aren’t seeing the username ‘123’ in the radcheck rows.

If the username field is the same between parent and child, a common way to sync these two up would be with an observer or a before_save callback. I’ll outline the before_save method below:

class Radcheck < ActiveRecord::Base
  set_table_name 'radcheck'
  attr_accessible :attribute_name, :username, :value, :op
  belongs_to :raduser

  before_save :sync_usernames

private

  def sync_usernames
    self.username = self.raduser.username
  end
end

I’ve tested this with Rails 3.1 and it works; however, I know I have run into issues accessing parent models within a child model in previous versions of Rails. In those cases, I had to put the before_save action on the parent model, and have it iterate over each child, setting the appropriate attributes that way.