Convert/serialize/marshal column type to richer type and back

[davetron5000]

I have scoured the docs and cannot find if there is a way to do this. Essentially I want to have the attribute method of a model return a custom type based on the underlying database type and back again.

For example, suppose my Widget model has the check_inventory_time_of_day attribute, that stores a time of day in 24 hour time, like "4:30" I store that as a text in the database. Suppose I have a class TimeOfDay that can interpret that value.

I'd like:

Widget.first.check_inventory_time_of_day #=> <#TimeOfDay hour=4 minute=30>
widget.check_inventory_time_of_day = TimeOfDay.new(hour: 14, minute: 00)
widget.save #=> Writes "14:00" to the database

I can't find docs on how the attr readers/writers are created to know if they are safe to override and if they are all that needs overriding.

[jeremyevans]

You probably want to use the serialization plugin.

In pretty much all cases in Sequel, you can override the method, then call super to get the default behavior (methods defined automatically are generally defined in a module included in the class).

[davetron5000]

Ah, ok, that worked!

class Widget # ...
  plugin :serialization
  serialize_attributes [
    :to_s.to_proc,
    TimeOfDay.method(:parse),
  ], :check_inventory_time_of_day

end