Htykuut

here is my condition: i have a model named Game and a model named GameLevel, their relationship is like code below:

class Game < ApplicationRecord

  has_many :game_level



class GameLevel < ApplicationRecord

  belongs_to :game

here is my situation:

when a Game has a GameLevel which name is default, it should not have low, medium, high;

when a Game has a GameLevel which names are low, medium, high, it should not have default.

so how do i delete default when i creating(or updating when record exists) low, medium, high , and how do i delete low ,medium, high when i creating(or updating when record exists) default in rails model?

You can use before_save callback mentioned here
And you should use game_levels instead of game_level as convention.

As an example you can write something like this;

class GameLevel < ApplicationRecord #or ActiveRecord::Base

  belongs_to :game

  before_save :remove_unnecessary



  private

    def remove_unnecessary

      if self.name == "default"

        self.game.game_levels.where(name: ["low", "medium", "high"]).destroy_all()

      end

      if ["low", "medium", "high"].any?{ |type| self.name == type }

        self.game.game_levels.where(name: "default").destroy_all()

      end

    end

end

for destroy you can look to here

You can use below code

class GmaeLevel < ApplicationRecord

    belongs_to :game

    before_save :update_date

    private

       def update_date

           self.name == "default" ? self.game.game_levels.(name: ["low","medium","high"]).destroy_all : self.game.game_levels.where(name: "default").destroy

       end

end