Active Model XML serialization : undefined method `[]' for nil:NilClass - ruby-on-rails

Question

Originally from here, i'm posting a new thread to focus on my issue resolving around the "to_xml" method.
What i'm trying to do : make a conversion from a ruby Object (Whois::Record) to XML.
I am currently using ActiveModel but not ActiveRecord (eg previous thread for reasons)
Here is the relevant controller :
def lookup
domain = params[:domain]
#whois = Request.new
#whois.search(domain)
respond_to do |format|
if #whois != nil
format.html
format.json {render :json => #whois.body}
format.xml {render :xml => #whois}
else
format.html { render :new }
format.json { render json: #request.errors, status: :unprocessable_entity }
end
end
end
Please note that #whois is NOT a Whois::Record object, but a class that contains such object (in the body property)
And the view :
<% if #whois != nil %>
<%= #whois %>
<!--JSON-->
<%= #whois.body.to_json %>
<!--XML-->
<% byebug %>
<%= #whois.to_xml %>
<% end %>
Note that the to_json method works fine, so the fact that ruby throws a nilClass exception is quite weird.
Here is the stacktrace starting from to_xml :
/home/nico/.rvmruby (2.1.3) gems/activesupport-4.1.6/lib/active_support/xml_mini.rb:148:in _dasherize'
/home/nico/.rvmruby (2.1.3) gems/activesupport-4.1.6/lib/active_support/xml_mini.rb:140:inrename_key'
/home/nico/.rvmruby (2.1.3) gems/activesupport-4.1.6/lib/active_support/xml_mini.rb:119:in to_tag'
/home/nico/.rvmruby (2.1.3) gems/activesupport-4.1.6/lib/active_support/core_ext/hash/conversions.rb:88:inblock (2 levels) in to_xml'
/home/nico/.rvmruby (2.1.3) gems/activesupport-4.1.6/lib/active_support/core_ext/hash/conversions.rb:88:in each'
/home/nico/.rvmruby (2.1.3) gems/activesupport-4.1.6/lib/active_support/core_ext/hash/conversions.rb:88:inblock in to_xml'
/home/nico/.rvmruby (2.1.3) gems/builder-3.2.2/lib/builder/xmlbase.rb:175:in call'
/home/nico/.rvmruby (2.1.3) gems/builder-3.2.2/lib/builder/xmlbase.rb:175:in_nested_structures'
/home/nico/.rvmruby (2.1.3) gems/builder-3.2.2/lib/builder/xmlbase.rb:68:in tag!'
/home/nico/.rvmruby (2.1.3) gems/activesupport-4.1.6/lib/active_support/core_ext/hash/conversions.rb:87:into_xml'
app/models/request.rb:26:in `to_xml'
Byebug gives me a lead as such :
to_xml > ActiveSupport::SafeBuffer::OutpuBuffer#safe_concat
153: def safe_concat(value)
=> 154: raise SafeConcatError unless html_safe?
155: original_concat(value)
156: end
note : html_safe? is set at 'true' here, and value equals "\t"
original_concat
File activesupport/lib/active_support/core_ext/string/output_safety.rb, line 132
Alias to original_concat
def concat(value)
if !html_safe? || value.html_safe?
super(value)
else
super(ERB::Util.h(value))
end
end
And when i step over i come back to the to_xml method, that's throwing a tantrum about not having a class to call upon methhods. I would be grateful for any help, thanks.
Edit
Here is the class Request from my model :
#This is a generic class for checking Key authenticity and sending requests to the engine
#Furthermore, this class will contain the WHOIS response in body
include ActiveModel::Model
include ActiveModel::Serializers::JSON
include ActiveModel::Serializers::Xml
attr_accessor :body
def attributes
{body => nil}
end
def to_xml(options = {})
to_xml_opts = {:skip_types => true} # no type information, not such a great idea!
to_xml_opts.merge!(options.slice(:builder, :skip_instruct))
# a builder instance is provided when to_xml is called on a collection of instructors,
# in which case you would not want to have <?xml ...?> added to each item
to_xml_opts[:root] ||= "instructor"
self.attributes.to_xml(to_xml_opts)
end
def search(domain)
# since rails compiles the code before executing a search once,
# we have to catch niClass exceptions and such
if domain != ( nil && true && "" )
c = Whois::Client.new
self.body = c.lookup(domain)
end
end
I've used this as from what i've understood XML tries to define a type for each attribute, and has problems with named objects. Here's the thread about to_xml and objects in rails