Methods

Constants

COLUMN_NAME_ORDER_WHITELIST = / \A (?:\w+\.)? \w+ (?:\s+asc|\s+desc)? (?:\s+nulls\s+(?:first|last))? \z /ix
 

Regexp whitelist. Matches the following:

"#{table_name}.#{column_name}"
"#{table_name}.#{column_name} #{direction}"
"#{table_name}.#{column_name} #{direction} NULLS FIRST"
"#{table_name}.#{column_name} NULLS LAST"
"#{column_name}"
"#{column_name} #{direction}"
"#{column_name} #{direction} NULLS FIRST"
"#{column_name} NULLS LAST"
COLUMN_NAME_WHITELIST = /\A(?:\w+\.)?\w+\z/i
 

Regexp whitelist. Matches the following:

"#{table_name}.#{column_name}"
"#{column_name}"

Instance Public methods

attribute_method?(attribute)

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
📝 Source code 
# File activerecord/lib/active_record/attribute_methods.rb, line 150
      def attribute_method?(attribute)
        super || (table_exists? && column_names.include?(attribute.to_s.sub(/=$/, "")))
      end
🔎 See on GitHub

attribute_names()

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"]
📝 Source code 
# File activerecord/lib/active_record/attribute_methods.rb, line 162
      def attribute_names
        @attribute_names ||= if !abstract_class? && table_exists?
          attribute_types.keys
        else
          []
        end
      end
🔎 See on GitHub

column_for_attribute(name)

Returns the column object for the named attribute. Returns a ActiveRecord::ConnectionAdapters::NullColumn if the named attribute does not exist.

class Person < ActiveRecord::Base
end

person = Person.new
person.column_for_attribute(:name) # the result depends on the ConnectionAdapter
# => #<ActiveRecord::ConnectionAdapters::Column:0x007ff4ab083980 @name="name", @sql_type="varchar(255)", @null=true, ...>

person.column_for_attribute(:nothing)
# => #<ActiveRecord::ConnectionAdapters::NullColumn:0xXXX @name=nil, @sql_type=nil, @cast_type=#<Type::Value>, ...>
📝 Source code 
# File activerecord/lib/active_record/attribute_methods.rb, line 246
      def column_for_attribute(name)
        name = name.to_s
        columns_hash.fetch(name) do
          ConnectionAdapters::NullColumn.new(name)
        end
      end
🔎 See on GitHub

dangerous_class_method?(method_name)

A class method is 'dangerous' if it is already (re)defined by Active Record, but not by any ancestors. (So 'puts' is not dangerous but 'new' is.)

📝 Source code 
# File activerecord/lib/active_record/attribute_methods.rb, line 125
      def dangerous_class_method?(method_name)
        BLACKLISTED_CLASS_METHODS.include?(method_name.to_s) || class_method_defined_within?(method_name, Base)
      end
🔎 See on GitHub

has_attribute?(attr_name)

Returns true if the given attribute exists, otherwise false.

class Person < ActiveRecord::Base
end

Person.has_attribute?('name')   # => true
Person.has_attribute?(:age)     # => true
Person.has_attribute?(:nothing) # => false
📝 Source code 
# File activerecord/lib/active_record/attribute_methods.rb, line 229
      def has_attribute?(attr_name)
        attribute_types.key?(attr_name.to_s)
      end
🔎 See on GitHub

instance_method_already_implemented?(method_name)

Raises an 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 Active Record. Check to make sure that you don't have an attribute or method with the same name.

Person.instance_method_already_implemented?(:name)
# => false
📝 Source code 
# File activerecord/lib/active_record/attribute_methods.rb, line 89
      def instance_method_already_implemented?(method_name)
        if dangerous_attribute_method?(method_name)
          raise DangerousAttributeError, "#{method_name} is defined by Active Record. Check to make sure that you don't have an attribute or method with the same name."
        end

        if superclass == Base
          super
        else
          # If ThisClass < ... < SomeSuperClass < ... < Base and SomeSuperClass
          # defines its own attribute method, then we don't want to overwrite that.
          defined = method_defined_within?(method_name, superclass, Base) &&
            ! superclass.instance_method(method_name).owner.is_a?(GeneratedAttributeMethods)
          defined || super
        end
      end
🔎 See on GitHub