Module: ActiveRecord::AttributeMethods::ClassMethods

Defined in:
lib/active_record/attribute_methods.rb

Instance Method Summary collapse

Instance Method Details

#attribute_method?(attribute) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_record/attribute_methods.rb', line 101

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

#attribute_methods_generated? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_record/attribute_methods.rb', line 52

def attribute_methods_generated?
  @attribute_methods_generated ||= false
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.



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# File 'lib/active_record/attribute_methods.rb', line 108

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) 


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# File 'lib/active_record/attribute_methods.rb', line 85

def dangerous_attribute_method?(name)
  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.



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# File 'lib/active_record/attribute_methods.rb', line 39

def define_attribute_methods
  # Use a mutex; we don't want two thread simaltaneously trying to define
  # attribute methods.
  @attribute_methods_mutex ||= Mutex.new

  @attribute_methods_mutex.synchronize do
    return if attribute_methods_generated?
    superclass.define_attribute_methods unless self == base_class
    super(column_names)
    @attribute_methods_generated = true
  end
end

#generated_external_attribute_methods ⇒ Object

We will define the methods as instance methods, but will call them as singleton methods. This allows us to use method_defined? to check if the method exists, which is fast and won’t give any false positives from the ancestors (because there are no ancestors).



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# File 'lib/active_record/attribute_methods.rb', line 60

def generated_external_attribute_methods
  @generated_external_attribute_methods ||= Module.new { extend self }
end

#instance_method_already_implemented?(method_name) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_record/attribute_methods.rb', line 69

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

Returns:

  • (Boolean) 


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# File 'lib/active_record/attribute_methods.rb', line 89

def method_defined_within?(name, klass, sup = klass.superclass)
  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 



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# File 'lib/active_record/attribute_methods.rb', line 64

def undefine_attribute_methods
  super
  @attribute_methods_generated = false
end