Class: RocketAMF::ClassMapping

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

Overview

Handles class name mapping between AS 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::CLASS_MAPPER.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 require subclassing the class mapper to add support.

Complete Replacement

In some cases, it may be beneficial to replace the default provider of class mapping completely. In this case, simply assign your class mapper class to RocketAMF::CLASS_MAPPER after loading RocketAMF. Through the magic of const_missing, CLASS_MAPPER is only defined after the first access by default, so you get no annoying warning messages. Custom class mappers must implement the following methods on instances: use_array_collection, get_as_class_name, get_ruby_obj, populate_ruby_obj, and props_for_serialization. In addition, it should have a class level mappings method that returns the mapping set it’s using, although its not required. If you’d like to see an example of what complete replacement offers, check out RubyAMF (github.com/rubyamf/rubyamf).

Example:

require 'rubygems'
require 'rocketamf'

RocketAMF.const_set(CLASS_MAPPER, MyCustomClassMapper)

C ClassMapper

The C class mapper, RocketAMF::Ext::FastClassMapping, has the same public API that RubyAMF::ClassMapping does, but has some additional performance optimizations that may interfere with the proper serialization of objects. To reduce the cost of processing public methods for every object, its implementation of props_for_serialization caches valid properties by class, using the class as the hash key for property lookup. This means that adding and removing properties from instances while serializing using a given class mapper instance will result in the changes not being detected. As such, it’s not enabled by default. So long as you aren’t planning on modifying classes during serialization using encode_amf, the faster C class mapper should be perfectly safe to use.

Activating the C Class Mapper:

require 'rubygems'
require 'rocketamf'

todo:review

RocketAMF::ClassMapper = RocketAMF::Ext::FastClassMapping

Class Attribute Summary collapse

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ ClassMapping

Returns a new instance of ClassMapping.



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# File 'lib/rocketamf/mapping/class_mapping.rb', line 110

def initialize
  @mappings             = self.class.mappings
  @use_array_collection = self.class.use_array_collection === true
end

Class Attribute Details

.use_array_collection ⇒ Object

Global configuration variable for sending Arrays as ArrayCollections. Defaults to false.



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# File 'lib/rocketamf/mapping/class_mapping.rb', line 70

def use_array_collection
  @use_array_collection
end

Instance Attribute Details

#use_array_collection ⇒ Object (readonly)

Properties



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# File 'lib/rocketamf/mapping/class_mapping.rb', line 102

def use_array_collection
  @use_array_collection
end

Class Method Details

.define {|mappings| ... } ⇒ Object

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

Example:

RocketAMF::CLASS_MAPPER.define do |m|
  m.map as: 'AsClass', ruby: 'RubyClass'
end

Yields:



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# File 'lib/rocketamf/mapping/class_mapping.rb', line 86

def define(&block) #:yields: mapping_set
  yield mappings
end

.mappings ⇒ Object

Returns the mapping set with all the class mappings that is currently being used.



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# File 'lib/rocketamf/mapping/class_mapping.rb', line 74

def mappings
  @mappings ||= MappingSet.new
end

.reset ⇒ Object

Reset all class mappings except the defaults and return use_array_collection to false



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# File 'lib/rocketamf/mapping/class_mapping.rb', line 92

def reset
  @use_array_collection = false
  @mappings             = nil
end

Instance Method Details

#get_as_class_name(obj) ⇒ Object

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



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# File 'lib/rocketamf/mapping/class_mapping.rb', line 117

def get_as_class_name(obj)
  # Get class name
  if obj.is_a?(String)
    ruby_class_name = obj
  elsif obj.is_a?(Types::TypedHash)
    ruby_class_name = obj.type
  elsif obj.is_a?(Hash)
    return nil
  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 



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

def get_ruby_obj(as_class_name)
  result = nil

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

  result
end

#populate_ruby_obj(target, props) ⇒ Object 



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# File 'lib/rocketamf/mapping/class_mapping.rb', line 154

def populate_ruby_obj(target, props)

  # Don't even bother checking if it responds to setter methods if it's a TypedHash
  if target.is_a?(Types::TypedHash)
    target.merge! props
    return target
  end

  # Some type of object
  hash_like = target.respond_to?("[]=")
  props.each do |key, value|
    if target.respond_to?("#{key}=")
      target.send("#{key}=", value)
    elsif hash_like
      target[key] = value
    end
  end

  target
end

#props_for_serialization(ruby_obj) ⇒ Object 



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# File 'lib/rocketamf/mapping/class_mapping.rb', line 181

def props_for_serialization(ruby_obj)
  result = {}

  # Handle hashes
  if ruby_obj.is_a?(Hash)

    # Stringify keys to make it easier later on and allow sorting
    ruby_obj.each { |k, v| result[k.to_s] = v }

  else

    # Generic object serializer
    @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)
      result[method_name.to_s] = ruby_obj.send(method_name) if method_def.arity == 0
    end
  end

  result
end