与Rails中的公共活动使用多对多关系

Question

我有一个作者拥有并且属于多本书的场景，反之亦然。在instructions之后建立one-to-many关系中的关联可以正常工作，但是当介绍many-to-many关系时，只要尝试创建或更新我的书籍模型，就会收到此错误消息。

undefined method `author' for #<Book:0x007fb91ae56a70> 

至于设立的作者是如何选择一本书我使用令牌输入提供的代码railscast here有一些改变。

class Author < ActiveRecord::Base 
    has_many :authorships 
    has_many :books, through: :authorships 

    def self.tokens(query) 
     authors = where("name like ?", "%#{query}%") 
     if authors.empty? 
      [{id: "<<<#{query}>>>", name: "Add New Author: \"#{query}\""}] 
     else 
      authors 
     end 
    end 

    def self.ids_from_tokens(tokens) 
     tokens.gsub!(/<<<(.+?)>>>/) {create!(name: $1).id} 
     tokens.split(',') 
    end 
end 

class Book < ActiveRecord::Base 
    attr_reader :author_tokens 

    include PublicActivity::Model 
    tracked owner: :author 

    has_many :authorships 
    has_many :authors, through: :authorships 

    def author_tokens=(ids) 
     self.author_ids = Author.ids_from_tokens(ids) 
    end 
end 

表单视图

<%= form_for(@book) do |f| %> 
    ... 

    <div class="field"> 
    <%= f.text_field :author_tokens, label: 'Author', input_html: {"data-pre" => @book.authors.to_json} %> 
    </div> 

    <div class="actions"> 
    <%= f.submit %> 
    </div> 
<% end %> 

Answer 1

class Author < ActiveRecord::Base 
    has_many :author_books, inverse_of: :author, dependent: :destroy 
    accepts_nested_attributes_for :author_books 
    has_many :books, through: :author_books 
end 

class Book < ActiveRecord::Base 
    has_many :author_books, inverse_of: :book, dependent: :destroy 
    accepts_nested_attributes_for :author_books 
    has_many :authors, through: :author_books 
end 

class AuthorBook < ActiveRecord::Base 
    validates_presence_of :book, :author 
end 

=============视图==============

<%= form_for @book do |f| %> 
    <%= f.text_field :title %> 
    <%= f.fields_for :author_books do |f2| %> 
    <%# will look through all author_books in the form builder.. %> 
    <%= f2.fields_for :author do |f3| %> 
     <%= f3.text_field :name %> 
    <% end %> 
    <% end %> 
<% end %> 

Answer 2

您的Book模型中没有author关系。

什么

tracked owner: :author 

确实基本上是调用您的图书实例方法author。您应该尝试:authors

但是！

这不会解决您的问题，因为owner只能是一个。所以你可以这样做：

tracked owner: proc {|_, book| book.authors.first } 

将所有者设置为书的第一作者。