default for serialized column in activerecord migration

Question

so i have a serialized column :dimensions, and in my migration, i would like to set the field to be a default hash.

i have tried...

create_table :shippin         


        

Answer 1

You can also specify a default class for the serialized column. See the docs.

class MyModel < ActiveRecord::Base
  serialize :dimensions_in, Hash
end

I've found that after_initialize blocks can cause a huge performance hit, especially if you would ever need to MyModel.all (eg: for a bulk export)

Without the class: MyModel.new.dimensions_in => nil

With a default Hash class: MyModel.new.dimensions_in => {}