Module: ActiveRecord::AttributeMethods::ClassMethods

Defined in:
activerecord/lib/active_record/attribute_methods.rb

Instance Method Summary collapse

Instance Method Details

#attribute_method?(attribute) ⇒ Boolean

Returns true if attribute is an attribute method and table exists, false otherwise.

class Person < ActiveRecord::Base
end

Person.attribute_method?('name')   # => true
Person.attribute_method?(:age=)    # => true
Person.attribute_method?(:nothing) # => false

Returns:

  • (Boolean) 


144
145
146
 
# File 'activerecord/lib/active_record/attribute_methods.rb', line 144

def attribute_method?(attribute)
  super || (table_exists? && column_names.include?(attribute.to_s.sub(/=$/, '')))
end

#attribute_names ⇒ Object

Returns an array of column names as strings if it’s not an abstract class and table exists. Otherwise it returns an empty array.

class Person < ActiveRecord::Base
end

Person.attribute_names
# => ["id", "created_at", "updated_at", "name", "age"]



156
157
158
159
160
161
162
 
# File 'activerecord/lib/active_record/attribute_methods.rb', line 156

def attribute_names
  @attribute_names ||= if !abstract_class? && table_exists?
      column_names
    else
      []
    end
end

#dangerous_attribute_method?(name) ⇒ Boolean

A method name is ‘dangerous’ if it is already defined by Active Record, but not by any ancestors. (So ‘puts’ is not dangerous but ‘save’ is.)

Returns:

  • (Boolean) 


119
120
121
 
# File 'activerecord/lib/active_record/attribute_methods.rb', line 119

def dangerous_attribute_method?(name) # :nodoc:
  method_defined_within?(name, Base)
end

#define_attribute_methods ⇒ Object

Generates all the attribute related methods for columns in the database accessors, mutators and query methods.



70
71
72
73
74
75
76
77
78
79
80
 
# File 'activerecord/lib/active_record/attribute_methods.rb', line 70

def define_attribute_methods # :nodoc:
  # Use a mutex; we don't want two thread simultaneously trying to define
  # attribute methods.
  generated_attribute_methods.synchronize do
    return false if @attribute_methods_generated
    superclass.define_attribute_methods unless self == base_class
    super(column_names)
    @attribute_methods_generated = true
  end
  true
end

#inherited(child_class) ⇒ Object

:nodoc:



57
58
59
60
 
# File 'activerecord/lib/active_record/attribute_methods.rb', line 57

def inherited(child_class) #:nodoc:
  child_class.initialize_generated_modules
  super
end

#initialize_generated_modules ⇒ Object

:nodoc:



62
63
64
65
66
 
# File 'activerecord/lib/active_record/attribute_methods.rb', line 62

def initialize_generated_modules # :nodoc:
  @generated_attribute_methods = Module.new { extend Mutex_m }
  @attribute_methods_generated = false
  include @generated_attribute_methods
end

#instance_method_already_implemented?(method_name) ⇒ Boolean

Raises a ActiveRecord::DangerousAttributeError exception when an Active Record method is defined in the model, otherwise false.

class Person < ActiveRecord::Base
  def save
    'already defined by Active Record'
  end
end

Person.instance_method_already_implemented?(:save)
# => ActiveRecord::DangerousAttributeError: save is defined by ActiveRecord

Person.instance_method_already_implemented?(:name)
# => false

Returns:

  • (Boolean) 


103
104
105
106
107
108
109
110
111
112
113
114
115
 
# File 'activerecord/lib/active_record/attribute_methods.rb', line 103

def instance_method_already_implemented?(method_name)
  if dangerous_attribute_method?(method_name)
    raise DangerousAttributeError, "#{method_name} is defined by Active Record"
  end

  if superclass == Base
    super
  else
    # If B < A and A defines its own attribute method, then we don't want to overwrite that.
    defined = method_defined_within?(method_name, superclass, superclass.generated_attribute_methods)
    defined && !ActiveRecord::Base.method_defined?(method_name) || super
  end
end

#method_defined_within?(name, klass, sup = klass.superclass) ⇒ Boolean

:nodoc:

Returns:

  • (Boolean) 


123
124
125
126
127
128
129
130
131
132
133
 
# File 'activerecord/lib/active_record/attribute_methods.rb', line 123

def method_defined_within?(name, klass, sup = klass.superclass) # :nodoc:
  if klass.method_defined?(name) || klass.private_method_defined?(name)
    if sup.method_defined?(name) || sup.private_method_defined?(name)
      klass.instance_method(name).owner != sup.instance_method(name).owner
    else
      true
    end
  else
    false
  end
end

#undefine_attribute_methods ⇒ Object

:nodoc:



82
83
84
85
86
87
 
# File 'activerecord/lib/active_record/attribute_methods.rb', line 82

def undefine_attribute_methods # :nodoc:
  generated_attribute_methods.synchronize do
    super if @attribute_methods_generated
    @attribute_methods_generated = false
  end
end