Class: RocketAMF::ClassMapping

Inherits:
Object
  • Object
show all
Defined in:
lib/rocketamf/class_mapping.rb

Overview

Handles class name mapping between actionscript and ruby and assists in serializing and deserializing data between them. Simply map an AS class to a ruby class and when the object is (de)serialized it will end up as the appropriate class.

Example:

RocketAMF::ClassMapper.define do |m|
  m.map :as => 'AsClass', :ruby => 'RubyClass'
  m.map :as => 'vo.User', :ruby => 'Model::User'
end

Object Population/Serialization

In addition to handling class name mapping, it also provides helper methods for populating ruby objects from AMF and extracting properties from ruby objects for serialization. Support for hash-like objects and objects using attr_accessor for properties is currently built in, but custom classes may need custom support. As such, it is possible to create a custom populator or serializer.

Populators are processed in insert order and must respond to the can_handle? and populate methods.

class CustomPopulator
  def can_handle? obj
    true
  end

  def populate obj, props, dynamic_props
    obj.merge! props
    obj.merge!(dynamic_props) if dynamic_props
  end
end
RocketAMF::ClassMapper.object_populators << CustomPopulator.new

Serializers are also processed in insert order and must respond to the can_handle? and serialize methods.

class CustomSerializer
  def can_handle? obj
    true
  end

  def serialize obj
    {}
  end
end
RocketAMF::ClassMapper.object_serializers << CustomSerializer.new

Complete Replacement

In some cases, it may be beneficial to replace the default provider of class mapping completely. In this case, simply assign an instance of your own class mapper to RocketAMF::ClassMapper after loading RocketAMF. Through the magic of const_missing, ClassMapper is only defined after the first access by default, so you get no annoying warning messages. Custom class mappers must implement the following methods: get_as_class_name, get_ruby_obj, populate_ruby_obj, props_for_serialization.

Example:

require 'rubygems'
require 'rocketamf'

RocketAMF::ClassMapper = MyCustomClassMapper.new
# No warning about already initialized constant ClassMapper
RocketAMF::ClassMapper.class # MyCustomClassMapper

Defined Under Namespace

Classes: MappingSet

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ ClassMapping

:nodoc:



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# File 'lib/rocketamf/class_mapping.rb', line 124

def initialize #:nodoc:
  @object_populators = []
  @object_serializers = []
end

Instance Attribute Details

#object_populators ⇒ Object (readonly)

Array of custom object populators.



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# File 'lib/rocketamf/class_mapping.rb', line 119

def object_populators
  @object_populators
end

#object_serializers ⇒ Object (readonly)

Array of custom object serializers.



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# File 'lib/rocketamf/class_mapping.rb', line 122

def object_serializers
  @object_serializers
end

Instance Method Details

#define {|mappings| ... } ⇒ Object

Define class mappings in the block. Block is passed a MappingSet object as the first parameter.

Example:

RocketAMF::ClassMapper.define do |m|
  m.map :as => 'AsClass', :ruby => 'RubyClass'
end

Yields:

  • (mappings) 


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# File 'lib/rocketamf/class_mapping.rb', line 137

def define #:yields: mapping_set
  yield mappings
end

#get_as_class_name(obj) ⇒ Object

Returns the AS class name for the given ruby object. Will also take a string containing the ruby class name.



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# File 'lib/rocketamf/class_mapping.rb', line 148

def get_as_class_name obj
  # Get class name
  if obj.is_a?(String)
    ruby_class_name = obj
  elsif obj.is_a?(Values::TypedHash)
    ruby_class_name = obj.type
  else
    ruby_class_name = obj.class.name
  end

  # Get mapped AS class name
  mappings.get_as_class_name ruby_class_name
end

#get_ruby_obj(as_class_name) ⇒ Object

Instantiates a ruby object using the mapping configuration based on the source AS class name. If there is no mapping defined, it returns a RocketAMF::Values::TypedHash with the serialized class name.



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# File 'lib/rocketamf/class_mapping.rb', line 165

def get_ruby_obj as_class_name
  ruby_class_name = mappings.get_ruby_class_name as_class_name
  if ruby_class_name.nil?
    # Populate a simple hash, since no mapping
    return Values::TypedHash.new(as_class_name)
  else
    ruby_class = ruby_class_name.split('::').inject(Kernel) {|scope, const_name| scope.const_get(const_name)}
    return ruby_class.new
  end
end

#populate_ruby_obj(obj, props, dynamic_props = nil) ⇒ Object

Populates the ruby object using the given properties



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# File 'lib/rocketamf/class_mapping.rb', line 177

def populate_ruby_obj obj, props, dynamic_props=nil
  # Process custom populators
  @object_populators.each do |p|
    next unless p.can_handle?(obj)
    p.populate obj, props, dynamic_props
    return obj
  end

  # Fallback populator
  props.merge! dynamic_props if dynamic_props
  hash_like = obj.respond_to?("[]=")
  props.each do |key, value|
    if obj.respond_to?("#{key}=")
      obj.send("#{key}=", value)
    elsif hash_like
      obj[key.to_sym] = value
    end
  end
  obj
end

#props_for_serialization(ruby_obj) ⇒ Object

Extracts all exportable properties from the given ruby object and returns them in a hash



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# File 'lib/rocketamf/class_mapping.rb', line 200

def props_for_serialization ruby_obj
  # Proccess custom serializers
  @object_serializers.each do |s|
    next unless s.can_handle?(ruby_obj)
    return s.serialize(ruby_obj)
  end

  # Handle hashes
  if ruby_obj.is_a?(Hash)
    # Stringify keys to make it easier later on and allow sorting
    h = {}
    ruby_obj.each {|k,v| h[k.to_s] = v}
    return h
  end

  # Fallback serializer
  props = {}
  @ignored_props ||= Object.new.public_methods
  (ruby_obj.public_methods - @ignored_props).each do |method_name|
    # Add them to the prop hash if they take no arguments
    method_def = ruby_obj.method(method_name)
    props[method_name.to_s] = ruby_obj.send(method_name) if method_def.arity == 0
  end
  props
end

#reset ⇒ Object

Reset all class mappings except the defaults



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# File 'lib/rocketamf/class_mapping.rb', line 142

def reset
  @mappings = nil
end