Question

I have a form which has a select box with categories. If a particular category is selected, another select box/dropdown is displayed to the user. I need this second dropdown to be a required field when this category is selected.

I cannot add validates :course, :presence => {:message => 'Course cannot be blank.'} to the model because this field is not always required, I need some other way to make it required only when certain category is selected in the first dropbox.

Thanks for your help

Answer 1

You could try using the if argument to validates, like this:

validates :course, :presence => {:message => "Course cannot be blink."}, :if => Proc.new { |u| u.first_dropdown_value == 'value_that_you_validate_courses_for' }

For more information, check out the Rails documentation on conditional validation.