没有方法错误

Question

我正在 rails 4 中开展一个项目，其中一个用户可以拥有多个项目，并且许多人都与一个项目相关联。 IE。项目和用户共享多对多关系。

我使用此迁移代码创建了一个新的 table -

class CreateProjectsUsersJoin < ActiveRecord::Migration
  def change
    create_table :projects_users_joins, :id => false do |t|

        t.integer :user_id
        t.integer :project_id
    end

    add_index :projects_users_joins, ["user_id","project_id"]
  end
end

并通过以下方式添加关联 -

class Project < ActiveRecord::Base

    validates :name , :presence => true
    validates :description, :presence => true


    #associations
    has_and_belongs_to_many :users

end


class User < ActiveRecord::Base

    include CarrierWave::MiniMagick

    #removes the white spaces before validating the data 


    before_validation :strip_whitespace, :only => [:name,:email]

    #data validations
    validates :email, :presence =>true,  :uniqueness => {case_sensitive: false}, :format => { :with=> /([a-zA-Z0-9_\-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([a-zA-Z0-9\-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)/, :message => "please enter a valid e-mail" }
    validates :name, :presence=>true
    validates :password ,:presence =>true, :confirmation=> true #, :length =>{ :minimum=>6, :maximum=>30}, :format=>{:with=>/(?=.*\d)(?=.*[a-z])(?=.*[A-Z]).{6,30}/}

    #for the image
    mount_uploader :image, ImageUploader

    #for the password
    has_secure_password


    #associations
    has_many :issues
    has_many :comments
    has_and_belongs_to_many :projects

end


    #squishes the data(removes heading and trailing  white spaces and replaces multiple space by songle)
def strip_whitespace
    self.email = self.email.squish
    self.name = self.name.squish
end

当我运行在 rails 控制台上执行以下命令时，出现无方法错误 - 请帮助

pro = Project.find(1)  (works)
me = User.find(27) (works)
pro.users << me  (throws a no method defined error)

请帮忙

Answer 1

您输入的 table 名字有误。 As the docs say 默认连接 table 名称应该只是两个类的复数名称按词汇顺序用下划线连接。所以在这种情况下 projects_users。

如果您想要 projects_users_joins，那么您可以在两个 habtm 调用中提供 :join_table 选项，或者（我的建议）对该迁移进行 rake db:migrate:down ，然后删除 "_joins" 并再次迁移以创建默认的 table 名称。

没有方法错误

No method error

ruby-on-rails

has-and-belongs-to-many

ruby-on-rails-3

ruby-on-rails-4