Module: ActiveRecord::AttributeMethods

Defined in:
lib/gems/activerecord-2.2.2/lib/active_record/attribute_methods.rb

Overview

:nodoc:

Defined Under Namespace

Modules: ClassMethods

Constant Summary collapse

DEFAULT_SUFFIXES = 
%w(= ? _before_type_cast)
ATTRIBUTE_TYPES_CACHED_BY_DEFAULT = 
[:datetime, :timestamp, :time, :date]

Class Method Summary collapse

Instance Method Summary collapse

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(method_id, *args, &block) ⇒ Object

Allows access to the object attributes, which are held in the @attributes hash, as though they were first-class methods. So a Person class with a name attribute can use Person#name and Person#name= and never directly use the attributes hash – except for multiple assigns with ActiveRecord#attributes=. A Milestone class can also ask Milestone#completed? to test that the completed attribute is not nil or 0.

It’s also possible to instantiate related objects, so a Client class belonging to the clients table with a master_id foreign key can instantiate master through Client#master.



232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
 
# File 'lib/gems/activerecord-2.2.2/lib/active_record/attribute_methods.rb', line 232

def method_missing(method_id, *args, &block)
  method_name = method_id.to_s

  if self.class.private_method_defined?(method_name)
    raise NoMethodError.new("Attempt to call private method", method_name, args)
  end

  # If we haven't generated any methods yet, generate them, then
  # see if we've created the method we're looking for.
  if !self.class.generated_methods?
    self.class.define_attribute_methods
    if self.class.generated_methods.include?(method_name)
      return self.send(method_id, *args, &block)
    end
  end
  
  if self.class.primary_key.to_s == method_name
    id
  elsif md = self.class.match_attribute_method?(method_name)
    attribute_name, method_type = md.pre_match, md.to_s
    if @attributes.include?(attribute_name)
      __send__("attribute#{method_type}", attribute_name, *args, &block)
    else
      super
    end
  elsif @attributes.include?(method_name)
    read_attribute(method_name)
  else
    super
  end
end

Class Method Details

.included(base) ⇒ Object 



6
7
8
9
10
11
12
13
14
15
 
# File 'lib/gems/activerecord-2.2.2/lib/active_record/attribute_methods.rb', line 6

def self.included(base)
  base.extend ClassMethods
  base.attribute_method_suffix(*DEFAULT_SUFFIXES)
  base.cattr_accessor :attribute_types_cached_by_default, :instance_writer => false
  base.attribute_types_cached_by_default = ATTRIBUTE_TYPES_CACHED_BY_DEFAULT
  base.cattr_accessor :time_zone_aware_attributes, :instance_writer => false
  base.time_zone_aware_attributes = false
  base.class_inheritable_accessor :skip_time_zone_conversion_for_attributes, :instance_writer => false
  base.skip_time_zone_conversion_for_attributes = []
end

Instance Method Details

#query_attribute(attr_name) ⇒ Object 



318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
 
# File 'lib/gems/activerecord-2.2.2/lib/active_record/attribute_methods.rb', line 318

def query_attribute(attr_name)
  unless value = read_attribute(attr_name)
    false
  else
    column = self.class.columns_hash[attr_name]
    if column.nil?
      if Numeric === value || value !~ /[^0-9]/
        !value.to_i.zero?
      else
        !value.blank?
      end
    elsif column.number?
      !value.zero?
    else
      !value.blank?
    end
  end
end

#read_attribute(attr_name) ⇒ Object

Returns the value of the attribute identified by attr_name after it has been typecast (for example, “2004-12-12” in a data column is cast to a date object, like Date.new(2004, 12, 12)).



266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
 
# File 'lib/gems/activerecord-2.2.2/lib/active_record/attribute_methods.rb', line 266

def read_attribute(attr_name)
  attr_name = attr_name.to_s
  if !(value = @attributes[attr_name]).nil?
    if column = column_for_attribute(attr_name)
      if unserializable_attribute?(attr_name, column)
        unserialize_attribute(attr_name)
      else
        column.type_cast(value)
      end
    else
      value
    end
  else
    nil
  end
end

#read_attribute_before_type_cast(attr_name) ⇒ Object 



283
284
285
 
# File 'lib/gems/activerecord-2.2.2/lib/active_record/attribute_methods.rb', line 283

def read_attribute_before_type_cast(attr_name)
  @attributes[attr_name]
end

#respond_to?(method, include_private_methods = false) ⇒ Boolean

Returns:

  • (Boolean) 


341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
 
# File 'lib/gems/activerecord-2.2.2/lib/active_record/attribute_methods.rb', line 341

def respond_to?(method, include_private_methods = false)
  method_name = method.to_s
  if super
    return true
  elsif !include_private_methods && super(method, true)
    # If we're here than we haven't found among non-private methods
    # but found among all methods. Which means that given method is private.
    return false
  elsif !self.class.generated_methods?
    self.class.define_attribute_methods
    if self.class.generated_methods.include?(method_name)
      return true
    end
  end
    
  if @attributes.nil?
    return super
  elsif @attributes.include?(method_name)
    return true
  elsif md = self.class.match_attribute_method?(method_name)
    return true if @attributes.include?(md.pre_match)
  end
  super
end

#respond_to_without_attributes? ⇒ Object

A Person object with a name attribute can ask person.respond_to?(:name), person.respond_to?(:name=), and person.respond_to?(:name?) which will all return true.



340
 
# File 'lib/gems/activerecord-2.2.2/lib/active_record/attribute_methods.rb', line 340

alias :respond_to_without_attributes? :respond_to?

#unserializable_attribute?(attr_name, column) ⇒ Boolean

Returns true if the attribute is of a text column and marked for serialization.

Returns:

  • (Boolean) 


288
289
290
 
# File 'lib/gems/activerecord-2.2.2/lib/active_record/attribute_methods.rb', line 288

def unserializable_attribute?(attr_name, column)
  column.text? && self.class.serialized_attributes[attr_name]
end

#unserialize_attribute(attr_name) ⇒ Object

Returns the unserialized object of the attribute.



293
294
295
296
297
298
299
300
301
302
 
# File 'lib/gems/activerecord-2.2.2/lib/active_record/attribute_methods.rb', line 293

def unserialize_attribute(attr_name)
  unserialized_object = object_from_yaml(@attributes[attr_name])

  if unserialized_object.is_a?(self.class.serialized_attributes[attr_name]) || unserialized_object.nil?
    @attributes.frozen? ? unserialized_object : @attributes[attr_name] = unserialized_object
  else
    raise SerializationTypeMismatch,
      "#{attr_name} was supposed to be a #{self.class.serialized_attributes[attr_name]}, but was a #{unserialized_object.class.to_s}"
  end
end

#write_attribute(attr_name, value) ⇒ Object

Updates the attribute identified by attr_name with the specified value. Empty strings for fixnum and float columns are turned into nil.



307
308
309
310
311
312
313
314
315
 
# File 'lib/gems/activerecord-2.2.2/lib/active_record/attribute_methods.rb', line 307

def write_attribute(attr_name, value)
  attr_name = attr_name.to_s
  @attributes_cache.delete(attr_name)
  if (column = column_for_attribute(attr_name)) && column.number?
    @attributes[attr_name] = convert_number_column_value(value)
  else
    @attributes[attr_name] = value
  end
end