Rails的自定义验证在多个属性

Question

我有以下的用户模型一个Rails应用程序：

卡车 用户

的卡车属于具有下列关联用户：

class Unit < ActiveRecord::Base 
    belongs_to :primary_crew_member, :foreign_key => :primary_crew_member_id, :class_name => 'User' 
    belongs_to :secondary_crew_member, :foreign_key => :secondary_crew_member_id, :class_name => 'User' 
end 

在Truck模型我有验证，以确保primary_crew_member_id和secondary_crew_member_id始终存在，因为Truck不能有用户/机组人员。

我希望能够做的是以下几点：

• 验证主要或次要机组成员（用户）没有分配到任何其他卡车
• 拓展上验证我需要确定卡车A上的John Doe是否是主要船员，他不能被分配到任何其他卡车上的主要或次要位置。
• 进一步扩大李四不应该能够采取两种中小学插槽在给定的卡车（双排班）

我一派，并想出了一个验证像主插槽验证所以：

验证：primary_multiple_assignment

def primary_multiple_assignment 
     if Truck.has_primary(primary_crew_member_id) 
     errors.add(:base, "User has already been assigned to another truck.") 
     end 
    end 

    def self.has_primary(primary_crew_member_id) 
     primary = Truck.where(primary_crew_member_id: primary_crew_member_id).first 
     !primary.nil? 
    end 

这似乎是工作，我可以确保没有用户被分配到一个主卡槽任何卡车除了单一的一个。但是，我需要能够满足我的验证要求，如上所述。所以基本上我试图验证多个列在一个单一的方法，但我不知道如何工作。

我已经阅读了Rails自定义验证指南，我几乎卡住了。任何您可能需要帮助的信息将不胜感激。与此同时，我会继续修补和搜索以找到解决方案。

Answer 1

您可以采用两种验证的做到这一点：

# validate that the primary or secondary crew member (user) is not assigned to 
# any other truck 
validates :primary_crew_member, uniqueness: true 
validates :secondary_crew_member, uniqueness: true 

# validate that the primary crew member can't be secondary crew member on any 
# truck (including current one) 
validate :primary_not_to_be_secondary 

# validate that the secondary crew member can't be primary crew member on any  
# truck (including current one) 
validate :secondary_not_to_be_primary 

def primary_not_to_be_secondary 
    if Truck.where(secondary_crew_member_id: primary_crew_member_id).present? 
     errors.add(:base, "Primary crew member already assigned as secondary crew member.") 
    end 
end 

def secondary_not_to_be_primary 
    if Truck.where(primary_crew_member_id: secondary_crew_member_id).present? 
     errors.add(:base, "Secondary crew member already assigned as primary crew member.") 
    end 
end