ActiveRecord::HasManyThroughAssociationNotFoundError 根据文档解决所有问题

Question

以下是我的模型：

class Client < ApplicationRecord

  has_many :client_authorization_rules
  has_many :projects, through: :client_authorization_rule

end

class Project < ApplicationRecord

  has_many :client_authorization_rules
  has_many :clients, through: :client_authorization_rule

end

class ClientAuthorizationRule < ApplicationRecord

  belongs_to :project
  belongs_to :client

  validates_presence_of :project
  validates_presence_of :client

end

所以，我已经按照文档进行了所有操作：http://guides.rubyonrails.org/association_basics.html#the-has-many-through-association

我得到的错误是当我做类似的事情时：

p.clients

这里"p"是一个项目。如果不出现以下错误，我什至无法访问项目的 "clients" 方法：

ActiveRecord::HasManyThroughAssociationNotFoundError: Could not find the association :client_authorization_rule in model Project

不确定我错过了什么。谢谢。我的 Rails 版本是 Rails 5.0.6 和 ruby 2.2.3。这是一些已知问题吗？我找不到任何有这个问题的人。

Answer 1

through: :client_authorization_rule

应该是client_authorization_rules

class Client < ApplicationRecord

  has_many :client_authorization_rules
  has_many :projects, through: :client_authorization_rules

end

class Project < ApplicationRecord

  has_many :client_authorization_rules
  has_many :clients, through: :client_authorization_rules

end

当您在 rails 5 中写入 belongs_to :project 时，还有一件事作为旁注，它自动意味着在保存之前需要 project_id。所以没有validates_presence_of :project

的感觉

class ClientAuthorizationRule < ApplicationRecord

  belongs_to :project #it means that project_id required is true
  belongs_to :client  #it means that client_id required is true

  #validates_presence_of :project
  #validates_presence_of :client

end

Answer 2

关注

class Client < ApplicationRecord

  has_many :client_authorization_rules
  has_many :projects, through: :client_authorization_rule

end

class Project < ApplicationRecord

  has_many :client_authorization_rules
  has_many :clients, through: :client_authorization_rule

end

应该是

class Client < ApplicationRecord    
  has_many :client_authorization_rules
  has_many :projects, through: :client_authorization_rules    
end

class Project < ApplicationRecord    
  has_many :client_authorization_rules
  has_many :clients, through: :client_authorization_rules    
end

注意：- through: :client_authorization_rule 应该是 through: :client_authorization_rules

ActiveRecord::HasManyThroughAssociationNotFoundError 根据文档解决所有问题

ActiveRecord::HasManyThroughAssociationNotFoundError issue with everything as per the Docs

ruby

activerecord

ruby-on-rails

associations