How to raise an ActiveRecord::Rollback exception and return a value together?

Question

I have a model that uses a `acts_as_nested_set` fork, and I've added a method to the model to save the model and move the node into the set in one transaction. This method calls a validation method to make sure the move is valid, which returns true or false. If the validation fails, I want my save method to raise `ActiveRecord::Rollback` to rollback the transaction, but also return false to the caller. My model looks like this: ``` class Category < ActiveRecord::Base acts_as_nested_set :dependent => :destroy, :scope => :journal def save_with_place_in_set(parent_id) Category.transaction do return false if !save_without_place_in_set if !validate_move parent_id raise ActiveRecord::Rollback and return false else place_in_nested_set parent_id return true end end end alias_method_chain :save, :place_in_set def validate_move(parent_id) # return true or false if the move is valid # ... end def place_in_nested_set(parent_id) # place the node in the correct place in the set # ... end end ``` Ho…

Accepted Answer

You could store the value you want returned from the function in a variable and return that outside the transaction block. E.g.

```
  def save_with_place_in_set(parent_id)
    return_value = false
    Category.transaction do
      if !save_without_place_in_set
        return_value = false
      elsif !validate_move parent_id
        return_value = false
        raise ActiveRecord::Rollback
      else
        place_in_nested_set parent_id
        return_value = true
      end
    end
    return return_value
  end
```

I've set the return_value to false initially as the only other way you can get out of that transaction block is if one of the other methods raises `ActiveRecord::Rollback` I believe.

How to raise an ActiveRecord::Rollback exception and return a value together?

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