rails state machine transitions & guards / validations

I can't seem to figure out how to make validations work correctly with a state machine. IE I'd like to do certain validations before allowing the new state of publish:

Transitions, the gem I'm using has a guard method but i can't seem to figure out how to use it correctly for more than one validation.

Tried simply applying basic validations like so:

validate_presence_of :age, :if => :publish? #

https://github.com/qoobaa/transitions

UPDATE: This seems to work like I want it to, but my next question is how can I lump all the validations together to simplify my method? I feel like I'm making it a lot more complicated than it could be and much less robust. Any ideas?

  state_machine do 
    state :draft
    state :active
    state :offline

    event :publish do
      transitions :to => :active, :from => :draft, :on_transition => :do_submit_to_user, :guard => :publish?
    end

  end

  def publish?
    unless description.blank? || invalid_minimum_feature_tags || invalid_minimum_images
      return true
    else
      errors.add(:description, 'cannot be blank') if description.blank?
      errors.add(:feature_list, 'must contain at least 4 features') if invalid_minimum_feature_tags
      errors.add(:photos, 'must exceed 4 to publish') if invalid_minimum_images
      return false
    end
  end

  def invalid_minimum_images
    if photos.size < 4
      return true
    else
      return false
    end
  end

  def invalid_min开发者_JAVA技巧imum_feature_tags
    if feature_list.size < 4
      return true
    else
      return false
    end
  end

With SimpleStateMachine the code would look like this:

def publish
  unless description.blank? || invalid_minimum_feature_tags || invalid_minimum_images
    do_submit_to_user
  else
    errors.add(:description, 'cannot be blank') if description.blank?
    errors.add(:feature_list, 'must contain at least 4 features') if invalid_minimum_feature_tags
    errors.add(:photos, 'must exceed 4 to publish') if invalid_minimum_images
  end
end
event :publish, :draft => :active

def invalid_minimum_images
  ...
end

def invalid_minimum_feature_tags
  ...
end