[](attr_name) Instance Public methods Returns the value of the attribute identified by attr_name after it has been typecast (for example, â2004-12-12â in a date column is cast to a date object, like Date.new(2004, 12, 12)). It raises ActiveModel::MissingAttributeError if the identified attribute is missing. Alias for the read_attribute method. class Person < ActiveRecord::Base belongs_to :organization end person = Person.new(name: 'Francesco', age: '22') person[:name] # =>

[]=(attr_name, value) Instance Public methods Updates the attribute identified by attr_name with the specified value. (Alias for the protected write_attribute method). class Person < ActiveRecord::Base end person = Person.new person[:age] = '22' person[:age] # => 22 person[:age] # => Fixnum

attribute_for_inspect(attr_name) Instance Public methods Returns an #inspect-like string for the value of the attribute attr_name. String attributes are truncated upto 50 characters, Date and Time attributes are returned in the :db format, Array attributes are truncated upto 10 values. Other attributes return the value of #inspect without modification. person = Person.create!(name: 'David Heinemeier Hansson ' * 3) person.attribute_for_inspect(:name) # => "\"David Heinemeier Han

attribute_names() Instance Public methods Returns an array of names for the attributes available on this object. class Person < ActiveRecord::Base end person = Person.new person.attribute_names # => ["id", "created_at", "updated_at", "name", "age"]

attribute_present?(attribute) Instance Public methods Returns true if the specified attribute has been set by the user or by a database load and is neither nil nor empty? (the latter only applies to objects that respond to empty?, most notably Strings). Otherwise, false. Note that it always returns true with boolean attributes. class Task < ActiveRecord::Base end person = Task.new(title: '', is_done: false) person.attribute_present?(:title) # => false person.attribute_pres

attributes() Instance Public methods Returns a hash of all the attributes with their names as keys and the values of the attributes as values. class Person < ActiveRecord::Base end person = Person.create(name: 'Francesco', age: 22) person.attributes # => {"id"=>3, "created_at"=>Sun, 21 Oct 2012 04:53:04, "updated_at"=>Sun, 21 Oct 2012 04:53:04, "name"=>"Francesco", "age"=>22}

column_for_attribute(name) Instance Public methods Returns the column object for the named attribute. Returns nil if the named attribute not exists. class Person < ActiveRecord::Base end person = Person.new person.column_for_attribute(:name) # the result depends on the ConnectionAdapter # => #<ActiveRecord::ConnectionAdapters::SQLite3Column:0x007ff4ab083980 @name="name", @sql_type="varchar(255)", @null=true, ...> person.column_for_attribute(:nothing) # => nil

has_attribute?(attr_name) Instance Public methods Returns true if the given attribute is in the attributes hash, otherwise false. class Person < ActiveRecord::Base end person = Person.new person.has_attribute?(:name) # => true person.has_attribute?('age') # => true person.has_attribute?(:nothing) # => false

respond_to?(name, include_private = false) Instance Public methods 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. It also define the attribute methods if they have not been generated. class Person < ActiveRecord::Base end person = Person.new person.respond_to(:name) # => true person.respond_to(:name=) # => true person.respond_to(:name?) # => true pers

changed_for_autosave?() Instance Public methods Returns whether or not this record has been changed in any way (including whether any of its nested autosave associations are likewise changed)