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 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::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 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::ClassMapper = MyCustomClassMapper
# No warning about already initialized constant ClassMapper
RocketAMF::ClassMapper # 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'
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

Copies configuration from class level configs to populate object



152
153
154
155
 
# File 'lib/rocketamf/class_mapping.rb', line 152

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.



121
122
123
 
# File 'lib/rocketamf/class_mapping.rb', line 121

def use_array_collection
  @use_array_collection
end

Instance Attribute Details

#use_array_collection ⇒ Object (readonly)

Returns the value of attribute use_array_collection.



149
150
151
 
# File 'lib/rocketamf/class_mapping.rb', line 149

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

Yields:



137
138
139
 
# File 'lib/rocketamf/class_mapping.rb', line 137

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.



125
126
127
 
# File 'lib/rocketamf/class_mapping.rb', line 125

def mappings
  @mappings ||= MappingSet.new
end

.reset ⇒ Object

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



143
144
145
146
 
# File 'lib/rocketamf/class_mapping.rb', line 143

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.



159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
 
# File 'lib/rocketamf/class_mapping.rb', line 159

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
  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

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



178
179
180
181
182
183
184
185
186
187
 
# File 'lib/rocketamf/class_mapping.rb', line 178

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. props and dynamic_props will be hashes with symbols for keys.



191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
 
# File 'lib/rocketamf/class_mapping.rb', line 191

def populate_ruby_obj obj, props, dynamic_props=nil
  props.merge! dynamic_props if dynamic_props

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

  # Some type of object
  hash_like = obj.respond_to?("[]=")
  props.each do |key, value|
    if obj.respond_to?("#{key}=")
      obj.send("#{key}=", value)
    elsif hash_like
      obj[key] = 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. If overriding, make sure to return a hash wth string keys unless you are only going to be using the native C extensions, as the pure ruby serializer performs a sort on the keys to acheive consistent, testable results.



217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
 
# File 'lib/rocketamf/class_mapping.rb', line 217

def props_for_serialization ruby_obj
  # 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

  # Generic object 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