Rails XML builder not rendering - ruby-on-rails

Question

I’m having an issue rendering XML in the response body of a request in a Rails 4 application. In the example below the response body is blank. I’ve put a debugger in the template so I know it runs through it but doesn’t render anything out.
I created a simple rails app to demonstrate the issue I’m having using builder to return xml. Can anyone point me to the (probably stupid simple) problem with this example?
Here are the controller, template, and test:
controllers/bars_controller.rb
require 'builder'
class BarsController < ApplicationController
before_action :set_bar, only: [:show]
# GET /bars/1
# GET /bars/1.json
def show
#xml = Builder::XmlMarkup.new
render template: 'bars/show.xml.builder', formats: [:xml]
end
private
# Use callbacks to share common setup or constraints between actions.
def set_bar
#bar = Bar.find(params[:id])
end
# Never trust parameters from the scary internet, only allow the white list through.
def bar_params
params.require(:bar).permit(:foo, :bar)
end
end
/views/bars/show.xml.builder
#xml.instruct!
#xml.bar do
#xml.foo(#bar.foo)
#xml.bar(#bar.bar)
end
/test/controllers/bars_controller_test.rb
require 'test_helper'
class BarsControllerTest < ActionController::TestCase
setup do
#bar = bars(:one)
end
test "should show bar" do
get :show, id: #bar
assert_response :success
assert_match "<bar>", response.body
end
end
debugging session
1: #xml.instruct!
2: binding.pry
=> 3: #xml.bar do
4: #xml.foo(#bar.foo)
5: #xml.bar(#bar.bar)
6: end
[2] pry(#<#<Class:0x007fc669e9f610>>)> #xml.bar do
[2] pry(#<#<Class:0x007fc669e9f610>>)* #xml.foo(#bar.foo)
[2] pry(#<#<Class:0x007fc669e9f610>>)* #xml.bar(#bar.bar)
[2] pry(#<#<Class:0x007fc669e9f610>>)* end
=> "<?xml version=\"1.0\" encoding=\"UTF-8\"?><bar><foo>MyString</foo><bar>MyString</bar></bar>"

Answer 1

It looks like creating the instance of the Builder::XmlMarkup.new is your problem. Remove the explicit creation of the builder so your controller looks like this:
def show
# You can also simplify by removing "bars/"
render 'bars/show.xml.builder', formats: [:xml]
end
And your view should look like this:
xml.instruct!
xml.bar do
xml.foo(#bar.foo)
xml.bar(#bar.bar)
end