ruby-on-rails - Rails 5.1 ActiveAdmin 错误未定义方法 `klass' 为 nil :NilClass

Question

当我尝试通过 ActiveAdmin 的仪表板查看两个特定模型时，我收到以下错误。我读过的所有内容都指向一个可能的关联问题，但我不确定如何纠正它。我看到很多人遇到同样的问题，但还没有找到任何解决方案。任何帮助将非常感激。

NoMethodError in Admin::Listings#index
undefined method `klass' for nil:NilClass

或

NoMethodError in Admin::Buildings#index
undefined method `klass' for nil:NilClass

模型

class Company < ApplicationRecord
  has_many :appointments, through: :listings, dependent: :destroy
  has_many :listings, through: :users, dependent: :destroy
  has_many :buildings, through: :users, dependent: :destroy
  has_many :users, dependent: :destroy
end

class User < ApplicationRecord
  belongs_to :company
  has_many :apointments, through: :listings
  has_many :listings, through: :buildings
  has_many :buildings
end

class Listing < ApplicationRecord
  has_many :companies, through: :users
  has_many :users, through: :buildings
  belongs_to :building
  has_many :appointments
end

class Building < ApplicationRecord
  has_many :companies, through: :users
  belongs_to :user
  has_many :appointments, through: :listings
  has_many :listings, dependent: :destroy
end


class Appointment < ApplicationRecord
  belongs_to :listing
  has_many :companies, through: :listings 
end

Answer 1

我认为您在 has_many :apointments, through: :lisings 中有错字

尝试使用 has_many :appointments, through: :listings

你少了一个p和一个t

没有解决方案，但https://github.com/activeadmin/activeadmin/issues/4470看起来也像你的问题。

另一个想法:

在具有 belong_to 的模型上并且您使用该关联进行通关，请尝试将其更改为单数。例如:


class Appointment < ApplicationRecord
belongs_to :listing
has_many :companies, through: :listing # nb: singular here
end


也许这会有帮助？