通过抛出错误建立has_many命名空间模型

Question

这些都是我有问题的模型。

class Admin::FilterGroup < ActiveRecord::Base
    has_many :admin_filter_groups_agents,class_name: "Admin::FilterGroupsAgents"
    has_many :agents, through: :admin_filter_groups_agents
end

class Admin::FilterGroupsAgents < ActiveRecord::Base
  belongs_to :admin_filter_group, :class_name => "Admin::FilterGroup",foreign_key: "admin_filter_group_id"
  belongs_to :agent, :class_name => "Agent",foreign_key: "agent_id"
end

class Agent < ActiveRecord::Base
    has_many :admin_filter_groups_agents,class_name: "Admin::FilterGroupsAgents"
    has_many :admin_filter_groups, through: :admin_filter_groups_agents
end

当我尝试调用Admin::FilterGroup.first.agents时，我得到以下错误：

    irb(main):001:0> Admin::FilterGroup.first.agents
  Admin::FilterGroup Load (0.1ms)  SELECT  `admin_filter_groups`.* FROM `admin_filter_groups`   ORDER BY `admin_filter_groups`.`id` ASC LIMIT 1
  Agent Load (63.2ms)  SELECT `agents`.* FROM `agents` INNER JOIN `admin_filter_groups_agents` ON `agents`.`id` = `admin_filter_groups_agents`.`agent_id` WHERE `admin_filter_groups_agents`.`filter_group_id` = 1
Mysql2::Error: Unknown column 'admin_filter_groups_agents.filter_group_id' in 'where clause': SELECT `agents`.* FROM `agents` INNER JOIN `admin_filter_groups_agents` ON `agents`.`id` = `admin_filter_groups_agents`.`agent_id` WHERE `admin_filter_groups_agents`.`filter_group_id` = 1
ActiveRecord::StatementInvalid: Mysql2::Error: Unknown column 'admin_filter_groups_agents.filter_group_id' in 'where clause': SELECT `agents`.* FROM `agents` INNER JOIN `admin_filter_groups_agents` ON `agents`.`id` = `admin_filter_groups_agents`.`agent_id` WHERE `admin_filter_groups_agents`.`filter_group_id` = 1

如何解决这个问题？

class CreateAdminFilterGroups < ActiveRecord::Migration
  def change
    create_table :admin_filter_groups do |t|
      t.string :name

      t.timestamps
    end
  end
end


class CreateAdminFilterGroupsAgents < ActiveRecord::Migration
  def change
    create_table :admin_filter_groups_agents do |t|
      t.references :admin_filter_group, index: true
      t.references :agent, index: true

      t.timestamps
    end
  end
end


class CreateAgents < ActiveRecord::Migration
  def change
    create_table :agents do |t|
      t.string :name
      t.references :user, index: true

      t.timestamps
    end
  end
end

Answer 1

尝试在关联的另一端指定foreign_key，在Agent和Admin::FilterGroup类中都是如此。

所以对于Agent

has_many :admin_filter_groups_agents, class_name: "Admin::FilterGroupsAgents", foreign_key: "agent_id"

对于Admin::FilterGroup

has_many :admin_filter_groups_agents,class_name: "Admin::FilterGroupsAgents", foreign_key: "admin_filter_group_id"