Association deletion in Rails

Scenes

When deleting a record, it needs to delete a certain type of record associated with it, for example:

class Category < ApplicationRecord
    has_many :blogs
end
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When deleting a category, all blogs associated with it need to be deleted.

solution

spelling one

class Category < ApplicationRecord
    has_many :blogs, dependent: :destroy
    # or
    # has_many :blogs, dependent: :delete_all
end
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shortcoming

dependent: :destroyIt is an n+1 operation. When a category needs to be deleted, all blogs belonging to this category will be found out and then deleted, which has performance risks. At this point you can use thedelete_all

spelling two

class Category < ApplicationRecord 
    def before_destroy 
        self.blogs.destroy_all # 此处n+1，可使用delete_all
    end
end
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If there are errors, please point them out.