Question

UPDATE:
If the after_validation callback is used, it works as desired (e.g. the false value is persistent). Still would like to know why that is, but I guess this is solved for my purposes 🙂

For a boolean field, I would like a callback in the model to set the default value to false instead of nil.

Currently when I create a new record, it initially shows the value as false, but then shows it as nil.

Wondering what’s going on here and if the desired behavior is possible w/ a callback.

This is in the model:

  after_save :default_is_forsale

  def default_is_forsale
    self.not_for_sale = false if self.not_for_sale.nil?
  end

Here is the rails console output (irrelevant bits omitted):

1.9.3p125 :001 > Item.create(name: "thing 4")
   (0.1ms)  begin transaction
  SQL (6.4ms)  INSERT INTO items [...]
   (190.8ms)  commit transaction
 => #<Item id: 20, name: "thing 4", not_for_sale: false> 

Cool, created the new record with a default value of false. But when I check again:

1.9.3p125 :002 > Item.last
  Item Load (0.3ms)  SELECT [...]
 => #<Item id: 20, name: "thing 4", not_for_sale: nil> 

Weird, now the value is nil.

But if I create a new record and explicitly set the value to false, it acts as I’d expect:

1.9.3p125 :003 > Item.create(name: "more thing", not_for_sale: false)
   (0.1ms)  begin transaction
  SQL (0.7ms)  INSERT INTO items [...]
   (225.2ms)  commit transaction
 => #<Item id: 21, name: "more thing", not_for_sale: false> 

When retrieved, the record still shows its boolean value of false

1.9.3p125 :004 > Item.last
  Item Load (0.3ms)  SELECT [...]
=> #<Item id: 21, name: "more thing", not_for_sale: false> 

BTW, I read elsewhere that the desired result is achievable via db migrations, but I am new to rails and would like to accomplish it through the model.

Thanks

Answer 1

Change your migration to set this boolean to false, as default. if there was code i’d show you.

I just read you were ‘new to rails’ but that doesn’t matter. You don’t need to do it in the model, unless you want that record to be true.