Hallo.
I have a user and a skill table joined in a SkillUser table. (has many through)
Now I try to get all Skills listed which are not already in the join table for user 1
In other words: user 1 has entries in the SkillUser table for skill 1 and 2. And I want to get skill 3…to …in the result, but not 1 or 2.
I have tried:
skills = Skill.sort.includes(:skill_users).where(‘skill_users.user_id NOT IN (?)’, @user.id)
But then I only get all the skills listed for all other users already listed in the SkillUser table.
Somehow I thing about a filter like
skill = Skill.sort
skill.filter(substract skills for user x which are already in SkillUser)
I have a user and a skill table joined in a SkillUser table. (has many
through)
Now I try to get all Skills listed which are not already in the join table
for user 1
Stop thinking in terms of tables and think about your models, e.g.
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You’re doing 2 queries by default plus the array subtraction
It’s better to just use a scope or a class method on Skill or some service class in my opinion but for brevity nothing tops that. The results would (should) be cached anyway.
