Module: HappyMapper

Defined in:
lib/happymapper.rb,
lib/happymapper/item.rb,
lib/happymapper/element.rb,
lib/happymapper/attribute.rb,
lib/happymapper/text_node.rb

Defined Under Namespace

Modules: ClassMethods Classes: Attribute, Element, Item, TextNode

Constant Summary collapse

DEFAULT_NS = 
"happymapper"

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.included(base) ⇒ Object 



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# File 'lib/happymapper.rb', line 12

def self.included(base)
  base.instance_variable_set("@attributes", {})
  base.instance_variable_set("@elements", {})
  base.instance_variable_set("@registered_namespaces", {})

  base.extend ClassMethods
end

Instance Method Details

#to_xml(builder = nil, default_namespace = nil) ⇒ String, Nokogiri::XML::Builder

Create an xml representation of the specified class based on defined HappyMapper elements and attributes. The method is defined in a way that it can be called recursively by classes that are also HappyMapper classes, allowg for the composition of classes.

Parameters:

  • builder (Nokogiri::XML::Builder) (defaults to: nil) —

    an instance of the XML builder which is being used when called recursively.

  • default_namespace (String) (defaults to: nil) —

    the name of the namespace which is the default for the xml being produced; this is specified by the element declaration when calling #to_xml recursively.

Returns:

  • (String, Nokogiri::XML::Builder) —

    return XML representation of the HappyMapper object; when called recursively this is going to return and Nokogiri::XML::Builder object.



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# File 'lib/happymapper.rb', line 389

def to_xml(builder = nil,default_namespace = nil)
  
  #
  # If to_xml has been called without a passed in builder instance that
  # means we are going to return xml output. When it has been called with
  # a builder instance that means we most likely being called recursively
  # and will return the end product as a builder instance. 
  #
  unless builder
    write_out_to_xml = true
    builder = Nokogiri::XML::Builder.new
  end
  
  #
  # Find the attributes for the class and collect them into an array
  # that will be placed into a Hash structure
  #
  attributes = self.class.attributes.collect do |attribute|
    
    #
    # If an attribute is marked as read_only then we want to ignore the attribute
    # when it comes to saving the xml document; so we wiill not go into any of
    # the below process
    # 
    unless attribute.options[:read_only]
    
      value = send(attribute.method_name)
    
      #
      # If the attribute defines an on_save lambda/proc or value that maps to 
      # a method that the class has defined, then call it with the value as a
      # parameter.
      #
      if on_save_action = attribute.options[:on_save]
        if on_save_action.is_a?(Proc)
          value = on_save_action.call(value)
        elsif respond_to?(on_save_action)
          value = send(on_save_action,value)
        end
      end
    
      #
      # Attributes that have a nil value should be ignored unless they explicitly
      # state that they should be expressed in the output.
      #
      if value || attribute.options[:state_when_nil]
        attribute_namespace = attribute.options[:namespace] || default_namespace
        [ "#{attribute_namespace ? "#{attribute_namespace}:" : ""}#{attribute.tag}", value ]
      else
        []
      end
      
    else
      []
    end
    
  end.flatten
  
  attributes = Hash[ *attributes ]

  #
  # Create a tag in the builder that matches the class's tag name and append
  # any attributes to the element that were defined above.
  #
  builder.send("#{self.class.tag_name}_",attributes) do |xml|
    
    #
    # Add all the registered namespaces to the root element.
    # When this is called recurisvely by composed classes the namespaces
    # are still added to the root element
    # 
    # However, we do not want to add the namespace if the namespace is 'xmlns'
    # which means that it is the default namesapce of the code.
    #
    if self.class.instance_variable_get('@registered_namespaces') && builder.doc.root
      self.class.instance_variable_get('@registered_namespaces').each_pair do |name,href|
        name = nil if name == "xmlns"
        builder.doc.root.add_namespace(name,href)
      end
    end
    
    #
    # If the object we are persisting has a namespace declaration we will want
    # to use that namespace or we will use the default namespace.
    # When neither are specifed we are simply using whatever is default to the
    # builder
    #
    if self.class.respond_to?(:namespace) && self.class.namespace
      xml.parent.namespace = builder.doc.root.namespace_definitions.find { |x| x.prefix == self.class.namespace }
    elsif default_namespace
      xml.parent.namespace = builder.doc.root.namespace_definitions.find { |x| x.prefix == default_namespace }
    end

    
    #
    # When a content has been defined we add the resulting value
    # the output xml
    #
    if content = self.class.instance_variable_get('@content')
      
      unless content.options[:read_only]
        text_accessor = content.tag || content.name
        value = send(text_accessor)
      
        if on_save_action = content.options[:on_save]
          if on_save_action.is_a?(Proc)
            value = on_save_action.call(value)
          elsif respond_to?(on_save_action)
            value = send(on_save_action,value)
          end
        end
      
        builder.text(value)
      end
      
    end

    #
    # for every define element (i.e. has_one, has_many, element) we are
    # going to persist each one
    #
    self.class.elements.each do |element|
      
      #
      # If an element is marked as read only do not consider at all when 
      # saving to XML.
      # 
      unless element.options[:read_only]
        
        tag = element.tag || element.name
        
        #
        # The value to store is the result of the method call to the element,
        # by default this is simply utilizing the attr_accessor defined. However,
        # this allows for this method to be overridden
        #
        value = send(element.name)

        #
        # If the element defines an on_save lambda/proc then we will call that
        # operation on the specified value. This allows for operations to be 
        # performed to convert the value to a specific value to be saved to the xml.
        #
        if on_save_action = element.options[:on_save]
          if on_save_action.is_a?(Proc)
            value = on_save_action.call(value)
          elsif respond_to?(on_save_action)
            value = send(on_save_action,value)
          end 
        end

        #
        # Normally a nil value would be ignored, however if specified then
        # an empty element will be written to the xml
        #
        if value.nil? && element.options[:single] && element.options[:state_when_nil]
          xml.send("#{tag}_","")
        end
      
        #
        # To allow for us to treat both groups of items and singular items
        # equally we wrap the value and treat it as an array.
        #
        if value.nil?
          values = []
        elsif value.respond_to?(:to_ary) && !element.options[:single]
          values = value.to_ary
        else
          values = [value]
        end
      
        values.each do |item|

          if item.is_a?(HappyMapper)

            #
            # Other items are convertable to xml through the xml builder
            # process should have their contents retrieved and attached
            # to the builder structure
            #
            item.to_xml(xml,element.options[:namespace])

          elsif item
          
            item_namespace = element.options[:namespace] || default_namespace
          
            #
            # When a value exists we should append the value for the tag
            #
            if item_namespace
              xml[item_namespace].send("#{tag}_",item.to_s)
            else
              xml.send("#{tag}_",item.to_s)
            end

          else

            #
            # Normally a nil value would be ignored, however if specified then
            # an empty element will be written to the xml
            #
            xml.send("#{tag}_","") if element.options[:state_when_nil]

          end

        end
        
      end
    end

  end

  # Write out to XML, this value was set above, based on whether or not an XML
  # builder object was passed to it as a parameter. When there was no parameter
  # we assume we are at the root level of the #to_xml call and want the actual
  # xml generated from the object. If an XML builder instance was specified 
  # then we assume that has been called recursively to generate a larger 
  # XML document.
  write_out_to_xml ? builder.to_xml : builder
  
end