Question

I’m trying to have an Engineer be created by a checkbox in the Army form but it doesn’t get created. The name of the checkbox is siege and is part of my Army model:

models/army.rb

class Army < ActiveRecord::Base
 attr_accessible :siege
 attr_reader :siege
 validates_inclusion_of :siege, :in => [true, false]
 has_many :engineers

 def siege=(string_value)
   @siege = (string_value == '1')
 end
end

models/engineer.rb

class Engineer < ActiveRecord::Base
  belongs_to :user
  belongs_to :army
end

armies/new.html.erb

<%= form_for @army do |f| %>
  <%= f.check_box :siege %>
  <%= f.submit "Create Army" %>
<% end %>

controllers/armies_controller.rb

def new
  @army = Army.new
end

def create
  @army = current_user.armies.build(params[:army])
    if @army.save
      redirect_to new_army_path
    else
      render :new
    end
  end
end

models/army_observer.rb

class ArmyObserver < ActiveRecord::Observer
  def after_save(army)
    if army.siege
      Engineer.new({ :user_id => current_user.id, :army_id => :army_id })
    end
  end
end

The army gets created but the Engineer does not. What needs to be corrected in my code to enable this?

Answer 1

You are not saving the record after initialing it 🙂

.new just builds a record does not save it.

In observer change new to create!

Engineer.new({ :user_id => current_user.id, :army_id => :army_id })

to

Engineer.create({ :user_id => current_user.id, :army_id => :army_id })

or else save it after building the record

engineer= Engineer.new({ :user_id => current_user.id, :army_id => :army_id }) 
engneer.save

also you need to have your observer register in config to make it listen to activities

http://guides.rubyonrails.org/active_record_validations_callbacks.html#registering-observers