Question

In my “create” action on a form, I successfully save (1) MyObject to my local database and (2) OtherObject to a third-party database via its Ruby API. When something goes wrong with the save to the third party, I get an error in the form of a Ruby exception.

My question is: How do I stop the form submit and report the exception message to the client?

If this is not possible, what would be the best alternative?

Answer 1

Depending on whether you want to rollback your local database call, you might want to consider using Transactions. Something along these lines:

def create
  ActiveRecord::Base.transaction do
    @myobject = MyObject.create!(params[:myobject])
    begin
      # call third-party
    rescue Exception => e
      flash[:exception] = e.message
      raise ActiveRecord::Rollback # Raise this to cause a rollback on MyObject
    end
  end
  # redirect_to or render... might have to pick depending on if you got an exception
end

This will store the exception message into the flash which you can use to display to the user. Note Do not store the entire Exception object into the flash, you will definitely see overflow errors if your exception objects are too big.

If you’re not too concerned about rolling back the MyObject creation, then you can just use a simple begin…rescue similar to what I showed in my example. You may need to determine whether you want to do a redirect_to or render depending on whether an exception occurred, but you can always conditionally determine that based on whether flash[:exception].nil? is true or not.