conditional validates_associated


Have you guys noticed that conditional validation with validates_associated does not work well when you are creating a new record?

Consider this gist:

The Lawyer class has validates_associated on address conditioned on whether the Lawyer data comes from a known source or not. So, if lawyer.source equals to some string, then lawyer.address must not be validated. However, if I’m trying to create a new record, it is validated regardless of whether source is nil or not. Is it expected to behave like that? Is that a bug?



The behavior is intentional, though perhaps not documented as well as it should be. It has to do with the autosave behavior for has_many on new records - the part that enables you to build a new record, add some unsaved child records (phones, etc in your example) and then save the parent object and get all the others saved as well.

You should be able to turn off this validation by passing ‘validate: false’ to your has_many associations as needed.

–Matt Jones

I see. Thank you for the clarification. However, isn’t that behavior counter-intuitive? Why should “valid?” return a different thing depending on whether a nested model is saved or not? If you want to skip the validation of one nested model, but still validate other things, then your only option is doing something like: validate:false


object.valid? || object.delete

That also has the potential problem of leaving some of the nested model data behind in the database.

Maybe there’s some gem that changes that behavior. Anyhow, at least now I know what’s going on, I can come up with a workaround.



Better option: don’t save records to the DB that are invalid. That’s typically considered a bad thing, so Rails makes it hard to do.

I’d recommend extending the “extracted?” method into your related models:

class Lawyer < ActiveRecord::Base

has_many :phones, :inverse_of => :lawyer


class Phone < ActiveRecord::Base

belongs_to :lawyer, :inverse_of => :phones

validates_something_of :foo, :if => :extracted?

def extracted?




This has the advantage of making the validations you want to skip explicit (they get the :if => :extracted? condition) instead of just skipping them entirely when needed.

–Matt Jones