在rails中,保存active_record对象时,也会保存其关联的对象.但是has_one和has_many关联在保存对象时有不同的顺序.
我有三个简化模型：
class Team < ActiveRecord::Base has_many :players has_one :coach end class Player < ActiveRecord::Base belongs_to :team validates_presence_of :team_id end class Coach < ActiveRecord::Base belongs_to :team validates_presence_of :team_id end
我预计当调用team.save时,团队应该在其关联的教练和球员之前保存.
我使用以下代码来测试这些模型：
t = Team.new team.coach = Coach.new team.save!
team.save！返回true.
但在另一个测试中：
t = Team.new team.players << Player.new team.save!
team.save！给出以下错误：
> ActiveRecord::RecordInvalid: > Validation Failed: Players is invalid
我想出了team.save！按以下顺序保存对象：1)玩家,2)团队,3)教练.这就是我收到错误的原因：当玩家被保存时,团队还没有id,所以validates_presence_of：team_id在玩家中失败.
有人可以向我解释为什么按此顺序保存对象？这对我来说似乎不合逻辑.
解决方法
您应该使用“validates_associated”来实现这一目标
检查Here
有点像没有检查
class Team < ActiveRecord::Base has_many :players has_one :coach validates_associated :players,:coach ###MOST IMPORTANT LINE end class Player < ActiveRecord::Base belongs_to :team validates_presence_of :team_id end class Coach < ActiveRecord::Base belongs_to :team validates_presence_of :team_id end
在你的控制器中
t = Team.new @coach = t.build_coach(:column1=> "value1",:column2=> "value2" ) # This create new object with @coach.team_id= t.id @players = t.players.build t.save#This will be true it passes the validation for all i.e. Team,COach & Player also save all at once otherwise none of them will get saved.