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# File 'lib/measured/rails/active_record.rb', line 6
def measured(measured_class, *fields)
options = fields.
options = {}.merge(options)
measured_class = measured_class.constantize if measured_class.is_a?(String)
unless measured_class.is_a?(Class) && measured_class.ancestors.include?(Measured::Measurable)
raise Measured::Rails::Error, "Expecting #{ measured_class } to be a subclass of Measured::Measurable"
end
options[:class] = measured_class
fields.map(&:to_sym).each do |field|
raise Measured::Rails::Error, "The field #{ field } has already been measured" if measured_fields.key?(field)
measured_fields[field] = options
unit_field_name = if options[:unit_field_name]
measured_fields[field][:unit_field_name] = options[:unit_field_name].to_s
else
"#{ field }_unit"
end
value_field_name = if options[:value_field_name]
measured_fields[field][:value_field_name] = options[:value_field_name].to_s
else
"#{ field }_value"
end
define_method(field) do
value = public_send(value_field_name)
unit = public_send(unit_field_name)
return nil unless value && unit
instance = instance_variable_get("@measured_#{ field }") if instance_variable_defined?("@measured_#{ field }")
new_instance = begin
measured_class.new(value, unit)
rescue Measured::UnitError
nil
end
if instance == new_instance
instance
else
instance_variable_set("@measured_#{ field }", new_instance)
end
end
define_method("#{ field }=") do |incoming|
if incoming.is_a?(measured_class)
instance_variable_set("@measured_#{ field }", incoming)
precision = self.column_for_attribute(value_field_name).precision
scale = self.column_for_attribute(value_field_name).scale
rounded_to_scale_value = incoming.value.round(scale)
max = self.class.measured_fields[field][:max_on_assignment]
if max && rounded_to_scale_value > max
rounded_to_scale_value = max
elsif rounded_to_scale_value.to_i.to_s.length > (precision - scale)
raise Measured::Rails::Error, "The value #{rounded_to_scale_value} being set for column '#{value_field_name}' has too many significant digits. Please ensure it has no more than #{precision - scale} significant digits."
end
public_send("#{ value_field_name }=", rounded_to_scale_value)
public_send("#{ unit_field_name }=", incoming.unit.name)
else
instance_variable_set("@measured_#{ field }", nil)
public_send("#{ value_field_name}=", nil)
public_send("#{ unit_field_name }=", nil)
end
end
redefine_method("#{ unit_field_name }=") do |incoming|
unit_name = measured_class.unit_system.unit_for(incoming).try!(:name)
write_attribute(unit_field_name, unit_name || incoming)
end
end
end
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