# File activemodel/lib/active_model/type/value.rb, line 37
def cast(value)
  cast_value(value) unless value.nil?
end

Type casts a value from user input (e.g. from a setter). This value may be a string from the form builder, or a ruby object passed to a setter. There is currently no way to differentiate between which source it came from.

The return value of this method will be returned from ActiveRecord::AttributeMethods::Read#read_attribute. See also: #cast_value.

value The raw input, as provided to the attribute setter.

# File activemodel/lib/active_model/type/value.rb, line 64
def changed?(old_value, new_value, _new_value_before_type_cast)
  old_value != new_value
end

Determines whether a value has changed for dirty checking. old_value and new_value will always be type-cast. Types should not need to override this method.

# File activemodel/lib/active_model/type/value.rb, line 85
def changed_in_place?(raw_old_value, new_value)
  false
end

Determines whether the mutable value has been modified since it was read. Returns false by default. If your type returns an object which could be mutated, you should override this method. You will need to either:

• pass new_value to #serialize and compare it to raw_old_value

or

• pass raw_old_value to #deserialize and compare it to new_value

raw_old_value The original value, before being passed to deserialize.

new_value The current value, after type casting.

# File activemodel/lib/active_model/type/value.rb, line 23
def deserialize(value)
  cast(value)
end

Converts a value from database input to the appropriate ruby type. The return value of this method will be returned from ActiveRecord::AttributeMethods::Read#read_attribute. The default implementation just calls #cast.

value The raw input, as provided from the database.

# File activemodel/lib/active_model/type/value.rb, line 45
def serialize(value)
  value
end

Casts a value from the ruby type to a type that the database knows how to understand. The returned value from this method should be a String, Numeric, Date, Time, Symbol, true, false, or nil.

# File activemodel/lib/active_model/type/value.rb, line 121
def cast_value(value) # :doc:
  value
end

Convenience method for types which do not need separate type casting behavior for user and database inputs. Called by #cast for values except nil.