Customise message for validates_uniqueness_of

[Ricky Hopkins]

I am trying to convert an integer to a DAYNAME in my validation message

validates_uniqueness_of :day, scope: :store, :message => "already has a target for #{Date::DAYNAMES[self.day]}."

This does not seem to work, I cannot access the day value.

The following displays the correct value

validates_uniqueness_of :day, scope: :store, :message => "already has a target for %{value}."

This throws an error:

validates_uniqueness_of :day, scope: :store, :message => "already has a target for #{Date::DAYNAMES[%{value}]}."

Any help would be Amazing!

[Matt Jones]

Using double quotes with #{} will *definitely* not do what you want; the interpolation will be attempted at class-load time, not when the string is needed.

The value passed to :message is handed off to I18n.translate, so the docs for that may be some help.

It may be easier (and clearer) to just define a custom validation function that does what you want.

--Matt Jones

[Eric Saupe]

This is along the lines of what Matt is referring to.

class DayValidator < ActiveRecord::Validator
  def validate()
    if YOUR_TEST_FOR_INVALIDITY(record.day)
      date = Date::DAYNAMES[record.day]
      record.errors[:day] << "already has a target #{date}"
    end
  end
end

class YourClass < ActiveRecord::Base
  validates_with DayValidator
end