Having difficulty using validates_uniqueness_of with a specific condition

Question

My model, Goal, has these three attributes: goal_type, goal_length, and is_complete.
Goal belongs_to :user.

goal_type can only be "X", "Y", or "Z"

goal_length can only be "short", "mid", or "long"

is_complete can be true or false

I want there to only ever be one Goal (validates_uniqueness_of) with a specified goal_length and goal_type when looking at Goals that both belong to the same user and have is_complete set to false

Plain english examples:

If a user has a short X goal that they have not yet completed, they cannot create a new short X goal. If a user has a short X goal that they have completed, they can create a new short X goal.

This validation works, but does not check if the existing goals have their is_complete attribute set to true. If is_complete is true on the previously existing models, it is ok to create a new goal with the same attributes:

validates_uniqueness_of :goal_type, scope: [:goal_length, :user_id]

How would I add a check for the condition where the validation is ignored if the matching previous goal has is_complete set to true ?

Answer 1

This validation appears to work as expected:

validates_uniqueness_of :goal_type, scope: [:goal_length, :user_id],  conditions: -> { where(is_complete: false) }