Accept_nested_attributes_for 和新记录

发布于 2024-09-26 15:21:11 字数 662 浏览 1 评论 0原文

我将 Accepts_nested_attributes_for 与以下模型一起使用：

用户模型：

class User < ActiveRecord::Base

  has_many :competences
  has_many :skills, :through => :competences, :foreign_key => :skill_id

  accepts_nested_attributes_for :skills
end

技能模型：

class Skill < ActiveRecord::Base
  has_many :competences
  has_many :users, :through => :competences, :foreign_key => :user_id
end

能力模型：

class Competence < ActiveRecord::Base
  belongs_to :user
  belongs_to :skill
end

技能表有一个“名称”属性。如果已存在具有相同技能名称的记录，如何才能让 Accepts_nested_attributes_for 不创建新的技能记录？

原文

I'm using accepts_nested_attributes_for with the following models:

User model:

class User < ActiveRecord::Base

  has_many :competences
  has_many :skills, :through => :competences, :foreign_key => :skill_id

  accepts_nested_attributes_for :skills
end

Skill model:

class Skill < ActiveRecord::Base
  has_many :competences
  has_many :users, :through => :competences, :foreign_key => :user_id
end

Competence model:

class Competence < ActiveRecord::Base
  belongs_to :user
  belongs_to :skill
end

The Skill table has a "name" attribute. How can I have accepts_nested_attributes_for not create a new skill record if a record with the same skill name already exists?

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时光暖心i 2024-10-03 15:21:11

您可以通过验证技能名称的唯一性来避免创建新技能：

class Skill < ActiveRecord::Base
  validates_uniqueness_of :name
end

我想您真正想知道的是如何将现有技能与他们为新用户指定的名称相关联，而不是在以下情况下创建新技能：一个已经存在。

如果您尝试这样做，它向我建议属性实际上根本不应该嵌套。

如果您确实愿意，您可能可以使用 before_save 回调来完成此操作，但同样，它又违背了嵌套属性的目的：

class User << ActiveRecord::Base
  before_save :check_for_existing_skill
  def check_for_existing_skill
    if self.skill
      existing_skill = Skill.find_by_name(self.skill.name)
      if existing_skill
        self.skill = existing_skill
      end
    end
  end
end

You can avoid creating a new skill by validating the skill name to be unique:

class Skill < ActiveRecord::Base
  validates_uniqueness_of :name
end

I guess what you really want to know though, is how to associate the existing skill with the name they have specified to the new user instead of creating a new skill when one already exists.

If you are trying to do that it suggests to me that the attributes shouldn't actually be nested at all.

You could probably do it with a before_save callback if you really wanted to but again, it kind of defeats the purpose of nested attributes:

class User << ActiveRecord::Base
  before_save :check_for_existing_skill
  def check_for_existing_skill
    if self.skill
      existing_skill = Skill.find_by_name(self.skill.name)
      if existing_skill
        self.skill = existing_skill
      end
    end
  end
end

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