Question

我在事件和用户之间有一个has_and_belongs_to_many关系。

user.rb

class User < ActiveRecord::Base
  rolify
  has_and_belongs_to_many :events, join_table: :events_users
  after_create :assign_default_role

  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable

   def assign_default_role
     add_role(:basic)
   end
end

event.rb

class Event < ActiveRecord::Base
  rolify
  has_and_belongs_to_many :users, join_table: :events_users
end

当我想删除一个事件时，我会做两件事：

删除所有关联（来自events_users表）
销毁事件（来自事件表）

所以我写了这段代码来实现这个目标：

events_controller.rb

  def destroy
    @event.users.clear #remove all associations
    @event.destroy #destroy event

    respond_to do |format|
      flash[:success] = 'Event was successfully deleted.'
      format.html { redirect_to events_url }
      format.json { head :no_content }
    end
  end

清除联接表中的关联（@ event.users.clear）。

我在尝试销毁实际事件时遇到错误（@ event.destroy）。

  (0.7ms)  BEGIN
  SQL (0.4ms)  DELETE FROM "events_users" WHERE "events_users"."event_id" = $1  [["event_id", 13]]
PG::UndefinedTable: ERROR:  relation "events_roles" does not exist
LINE 5:                WHERE a.attrelid = '"events_roles"'::regclass
                                          ^
:               SELECT a.attname, format_type(a.atttypid, a.atttypmod),
                     pg_get_expr(d.adbin, d.adrelid), a.attnotnull, a.atttypid, a.atttypmod
                FROM pg_attribute a LEFT JOIN pg_attrdef d
                  ON a.attrelid = d.adrelid AND a.attnum = d.adnum
               WHERE a.attrelid = '"events_roles"'::regclass
                 AND a.attnum > 0 AND NOT a.attisdropped
               ORDER BY a.attnum

   (0.3ms)  ROLLBACK
ActiveRecord::StatementInvalid: PG::UndefinedTable: ERROR:  relation "events_roles" does not exist
LINE 5:                WHERE a.attrelid = '"events_roles"'::regclass
                                          ^
:               SELECT a.attname, format_type(a.atttypid, a.atttypmod),
                     pg_get_expr(d.adbin, d.adrelid), a.attnotnull, a.atttypid, a.atttypmod
                FROM pg_attribute a LEFT JOIN pg_attrdef d
                  ON a.attrelid = d.adrelid AND a.attnum = d.adnum
               WHERE a.attrelid = '"events_roles"'::regclass
                 AND a.attnum > 0 AND NOT a.attisdropped
               ORDER BY a.attnum

它似乎正在寻找“events_ 角色 ”表格，我不明白为什么。

（events_ 用户有意义，但events_ 角色突然出现）

帮助表示赞赏。

Answer 1

这与您在Event类中的'rolify'有关。

class Event < ActiveRecord::Base
  rolify
  ...

这是Rolify gem，它可能在DB中生成额外的表/字段。

Rails 4 - 销毁HABTM记录导致UndefinedTable

1 个答案: