use Erector for QuestionForm and AnswerKey builders

.rspec

@@ -0,0 +1 @@
+--color

Gemfile

@@ -1,7 +1,16 @@
 source "http://rubygems.org"
+
 gem 'nokogiri'
-gem 'jeweler'
-gem 'webmock'
 gem 'rest-client'
-gem 'rspec', "~>2"
-gem 'fakeweb'
+gem "erector", ">= 0.9.0.pre"
+
+group :development do
+  gem 'jeweler'
+end
+
+group :development, :test do
+  gem 'webmock'
+  gem 'rspec', "~>2"
+  gem 'fakeweb'
+  gem "wrong"
+end

lib/rturk/builders/answer_key_builder.rb

@@ -0,0 +1,39 @@
+require "erector/xml_widget"
+
+# see http://docs.amazonwebservices.com/AWSMechTurk/2008-08-02/AWSMturkAPI/index.html?ApiReference_CreateQualificationTypeOperation.html
+class RTurk::AnswerKey < Erector::XMLWidget
+
+  XMLNS = "http://mechanicalturk.amazonaws.com/AWSMechanicalTurkDataSchemas/2005-10-01/AnswerKey.xsd"
+
+  %w{
+  AnswerKey
+    Question
+      QuestionIdentifier
+      AnswerOption
+        SelectionIdentifier
+        AnswerScore
+      DefaultScore
+    QualificationValueMapping
+      PercentageMapping
+        MaximumSummedScore
+      ScaleMapping
+        SummedScoreMultiplier
+      RangeMapping
+        SummedScoreRange
+          InclusiveLowerBound
+          InclusiveUpperBound
+          QualificationValue
+        OutOfRangeQualificationValue
+  }.uniq.each do |element_name|
+    tag element_name
+    tag element_name, :snake_case
+  end
+
+  def content
+    answer_key :xmlns => XMLNS do
+      answer_key_content
+    end
+  end
+
+end
+

lib/rturk/builders/question_form_builder.rb

@@ -1,33 +1,86 @@
 require 'cgi'
 require 'uri'
+require "erector/xml_widget"
 
 module RTurk
-  class QuestionForm
+  # see http://docs.amazonwebservices.com/AWSMechTurk/2008-08-02/AWSMturkAPI/ApiReference_QuestionFormDataStructureArticle.html
+  # @param options hash (optional)
+  # ::xml:: raw xml (optional). If it starts with \<QuestionForm then it's used as the full QuestionForm value. Otherwise it is wrapped in a \<QuestionForm\> element. If it is nil then we use Erector to call its subclass' #question_form_content method.
+  class QuestionForm < Erector::XMLWidget
 
     XMLNS = "http://mechanicalturk.amazonaws.com/AWSMechanicalTurkDataSchemas/2005-10-01/QuestionForm.xsd"
 
-    # The QuestionForm data structure is hella complicated, so we're just treating it as a string for now. See
-    # http://docs.amazonwebservices.com/AWSMechTurk/2008-08-02/AWSMturkAPI/ApiReference_QuestionFormDataStructureArticle.html
+    needs :xml => nil
 
-    attr_accessor :text
+    def to_params
+      to_xml  # create a new output string and call 'content' via Erector
+    end
 
-    def initialize(text)
-      @text = text
+    # todo: fill out Application subelements
+    # todo: fill out EmbeddedBinary subelements
+    %w{
+    QuestionForm
+      Overview
+        Title
+        List
+        Binary
+          MimeType
+            Type
+            SubType
+          DataURL
+          AltText
+        Application
+        EmbeddedBinary
+        FormattedContent
+
+      Question
+        QuestionIdentifier
+        DisplayName
+        IsRequired
+        QuestionContent
+        AnswerSpecification
+          FreeTextAnswer
+            Constraints
+              IsNumeric
+              Length
+              AnswerFormatRegex
+            DefaultText
+            NumberOfLinesSuggestion
+          SelectionAnswer
+            MinSelectionCount
+            MaxSelectionCount
+            StyleSuggestion
+            Selections
+              Selection
+                SelectionIdentifier
+                  Text
+                  FormattedContent
+                  Binary
+              OtherSelection
+          FileUploadAnswer
+            MaxFileSizeInBytes
+            MinFileSizeInBytes
+    }.uniq.each do |element_name|
+      tag element_name
+      tag element_name, :snake_case unless element_name == 'Text'
     end
 
-    def to_params
-      if text =~ /^<QuestionForm/
-        text
+    tag "Text", "text_element"  # very sticky since 'text' is a core Erector method
+
+    def content
+      if @xml and @xml.strip =~ /^<QuestionForm/
+        rawtext @xml
       else
-        <<-XML
-<QuestionForm xmlns="#{XMLNS}">
-#{text}
-</QuestionForm>
-        XML
+        question_form :xmlns => XMLNS do
+          question_form_content
+        end
       end
     end
 
-  end
+    def question_form_content
+      rawtext @xml  # by default, use the parameter
+    end
 
+  end
 
 end

lib/rturk/operations/create_hit.rb

@@ -20,8 +20,12 @@ def question(*args)
       end
     end
 
-    def question_form(text)
-      @question = RTurk::QuestionForm.new(text)
+    def question_form(text_or_widget)
+      if text_or_widget.is_a? Erector::XMLWidget
+        @question = text_or_widget
+      else
+        @question = RTurk::QuestionForm.new(:xml => text)
+      end
     end
 
     def to_params

spec/builders/answer_key_builder_spec.rb

@@ -0,0 +1,26 @@
+require File.expand_path(File.join(File.dirname(__FILE__), '..', 'spec_helper'))
+require 'rturk/builders/answer_key_builder'
+
+module RTurk
+  describe AnswerKey do
+
+    before(:all) do
+    end
+
+    class SillyAnswerKey < AnswerKey
+      def answer_key_content
+        Question "Why did the chicken cross the road?"
+      end
+    end
+
+    it "is an abstract base class that calls down to 'answer_key_content' in its concrete subclasses" do
+      RTurk::SillyAnswerKey.new.to_xml.should ==
+        "<AnswerKey xmlns=\"#{RTurk::AnswerKey::XMLNS}\">" +
+          "<Question>Why did the chicken cross the road?</Question>" +
+        "</AnswerKey>"
+    end
+
+    # todo: test more
+
+  end
+end

spec/builders/question_form_builder_spec.rb

@@ -1,18 +1,75 @@
 require File.expand_path(File.join(File.dirname(__FILE__), '..', 'spec_helper'))
+require 'rturk/builders/question_form_builder'
 
-describe RTurk::QuestionForm do
+module RTurk
+  describe QuestionForm do
 
-  before(:all) do
-  end
+    before(:all) do
+    end
 
-  it "should build a question" do
-    question = RTurk::QuestionForm.new("[...]")
-    question.text.should == "[...]"
-    question.to_params.should == <<-XML
-<QuestionForm xmlns="#{RTurk::QuestionForm::XMLNS}">
-[...]
-</QuestionForm>
-    XML
-  end
+    it "should build a question, using its xml param as the full QuestionForm since it starts with <QuestionForm" do
+      xml = <<-XML
+      <QuestionForm xmlns="#{RTurk::QuestionForm::XMLNS}">
+      [...]
+      </QuestionForm>
+      XML
+      question = RTurk::QuestionForm.new(:xml => xml)
+      question.to_params.should == xml
+    end
+
+    it "should build a question, using its xml param as the QuestionForm content" do
+      question = RTurk::QuestionForm.new(:xml => "[...]")
+      question.to_params.should ==
+        "<QuestionForm xmlns=\"#{RTurk::QuestionForm::XMLNS}\">[...]</QuestionForm>"
+    end
+
+    class SillyQuestionForm < QuestionForm
+      def question_form_content
+        Question "Why did the chicken cross the road?"
+      end
+    end
 
+    it "is an abstract base class that calls down to 'question_form_content' in its concrete subclasses" do
+      RTurk::SillyQuestionForm.new.to_xml.should ==
+        "<QuestionForm xmlns=\"#{RTurk::QuestionForm::XMLNS}\">" +
+          "<Question>Why did the chicken cross the road?</Question>" +
+        "</QuestionForm>"
+    end
+
+    class AnotherSillyQuestionForm < QuestionForm
+      def question_form_content
+        question {
+          question_content {
+            Text "How many licks?" # note: Text vs text vs text_element gotcha
+          }
+          answer_specification {
+            free_text_answer {
+              constraints {
+                is_numeric true
+              }
+            }
+          }
+        }
+      end
+    end
+
+    it "allows snake_case element names" do
+      RTurk::AnotherSillyQuestionForm.new.to_xml.should ==
+        "<QuestionForm xmlns=\"#{RTurk::QuestionForm::XMLNS}\">" +
+          "<Question>" +
+            "<QuestionContent>" +
+              "<Text>How many licks?</Text>" +
+            "</QuestionContent>" +
+            "<AnswerSpecification>" +
+              "<FreeTextAnswer>" +
+                "<Constraints>" +
+                  "<IsNumeric>true</IsNumeric>" +
+                "</Constraints>" +
+              "</FreeTextAnswer>" +
+            "</AnswerSpecification>" +
+          "</Question>" +
+        "</QuestionForm>"
+    end
+
+  end
 end