Error rendering XML when render_nil is set to true and value is nil.

[konung]

Code:

class ProductRepresenter < Roar::Decorator
  include Roar::JSON
  include Roar::XML
  self.representation_wrap= nil

  Product.attribute_names.each do |attr|
    property attr.to_sym,  render_nil: true 
  end

 # This works fine  - cause this is a required attribute
  property :manufacturer, class: Manufacturer, decorator: ManufacturerRepresenter, render_nil: true

  # For the product in Question - this  :distribution_restriction is nil ( can be set to NULL if there is no restriction) so it causes a problem when trying to render xml
  property :distribution_restriction, class: DistributionRestriction, decorator: RestrictionRepresenter, render_nil: true

end

here is the error

ArgumentError: Requires a Node, NodeSet or String argument, and cannot accept a NilClass.
(You probably want to select a node from the Document with at() or search(), or create a new Node via Node.new().)
from /home/vagrant/.rbenv/versions/2.2.1/lib/ruby/gems/2.2.0/gems/nokogiri-.6.6.2/lib/nokogiri/xml/node.rb:803:in `coerce'

[apotonick]

Please try this with separate representers (one for XML, only) and give me a complete test setup so I have a chance to understand what you're doing (No test, just some pseudo code is ok).

BTW: You don't need to to_sym property names, strings are fine.
BTW2: Sorry to disappoint you but XML support in Representable is very very low on my very very full priority list, so don't get angry at me if things take a bit longer. ❤️

[konung]

let me simplify a bit - so I don't get into how I implemented restrictions - as this bug happens whenever an associated Representer doesn't have anything to render - in this case manufacturer_id is nil and therefore associated manufacture is also nil - and I say render it as blank
( I want to supply a full set of attributes regardless of the value they are holding or not holding :) on each api call)

class ProductRepresenter < Roar::Decorator
  include Roar::XML
  self.representation_wrap= nil

  Product.attribute_names.each do |attr|
    property attr,  render_nil: true
  end

  property :manufacturer, class: Manufacturer, decorator: ManufacturerRepresenter, render_nil: true
end

class ManufacturerRepresenter < Roar::Decorator
  include Roar::XML
  self.representation_wrap= nil

  property :id
  property :name
  property :code
end


class Product < ActiveRecord::Base
  belongs_to :manufacturer, inverse_of: :products
end


class Manufacturer < ActiveRecord::Base
  has_many :products, inverse_of: :manufacturer
end


class ProductsController < ApplicationController
  include Roar::Rails::ControllerAdditions
  %w(json xml).each do |response|
    represents response.to_sym, Product
  end
  respond_to :html, :json, :xml

  def show
    product = Product.include_all.find_by_id(params[:id])
    #include_all is a scope that eager loads all related associations 
    #( I don't want to call it using default scope - as that slows down
    # all other lookups that don't need this level of detail)
    respond_with product
  end

end

So when I call http://api.dev/products/1.xml and product doesn't have a manufacturer for instance - than I get that error above.

THis only happens in XML, not in JSON -