How can I rollback a rails save/transaction?

Question

In my controller I have some code like...

...
if user.save
    something = Something.where("thing = ?", thing)
    if !(something.nil?)
        render json: { something: something }
    else
        #I WOULD LIKE TO ROLLBACK THE user.save HERE
    end
else
    render json: { error: user.errors.full_messages }, status: :bad_request
end

I have tried

raise ActiveRecord::Rollback, "Could not create new User, Something was not found."
render json: { error: "Could not create new User, Something was not found"}, status: :unprocessable_entity

in place of the ROLLBACK COMMENT area above, but this does not work. The user.save ends up going through. It spits something out to 'rails s', but it does not rollback the last transaction.

Answer 1

You need to wrap the code in a transaction for the rollback to work properly. Here's the documentation: http://api.rubyonrails.org/classes/ActiveRecord/Transactions/ClassMethods.html

Something like

ActiveRecord::Base.transaction do
  # the code from your question
end

The key is that both the user.save call (which modifies the DB) and the raise ActiveRecord::Rollback call need to be in that block.