轨道has_many_through数据插入问题 [英] rails has_many_through data insertion question

问题描述

我有一个场景，模特的样子

I have a scenario where the models look like

create_table :users do |t|
  t.string :name
  t.timestamps
end

create_table :blogs do |t|
  t.string :url
  t.string :title
  t.text :description
  t.timestamps
end

create_table :posts do |t|
  t.integer :user_id, :null => false
  t.integer :blog_id, :null => false
  t.text :post_text
end

class Blog < ActiveRecord::Base
  has_many :users, :through =>:posts
  has_many :posts, :dependent=>true
end

class User < ActiveRecord::Base
  has_many :blogs
  has_many :posts, :through=>:blogs
end

class Post < ActiveRecord::Base
  belongs_to :blog
  belongs_to :user
end

我的问题是： 1.当创建一个用户，我想自动创建一个博客给他。

The question I have is: 1. When a user is created, I would like to create a blog for him automatically.

@user = User.find_or_create_by_name（用户名）

@user = User.find_or_create_by_name(user_name)

我如何去创建一个博客？    @blog = Blog.find_or_create_by_user_id（@user）

How do I go about creating a blog? @blog = Blog.find_or_create_by_user_id(@user)

我收到以下错误：

undefined method `find_or_create_by_user_id' for #<Class:0x1044735b0>

@blogs = @user.blogs

给我：

 Mysql::Error: Unknown column 'blogs.user_id' in 'where clause': SELECT * FROM `blogs` WHERE (`blogs`.user_id=1234)

我知道博客表没有user_id列。  但事实并非联接应该照顾它？ 我在做什么错在这里？

I know Blogs table does not have user_id column. But isn't the join supposed to take care of it? What am I doing wrong here?

感谢您的帮助

推荐答案

要使用Post模型的关联表，用户模式需要进行调整，以正确展示的关联。一旦这样做，你可以使用 after_create 来创建一个新创建的用户一个新的博客。

To use the Post model as the association table, the User model needs to be tweaked to properly demonstrate the association. Once done, you could use after_create to create a new blog for a newly created user.

class User < ActiveRecord::Base
  has_many :posts
  has_many :blogs, :through=>:posts
  after_create :add_blog

  private
  def add_blog
    blogs << Blog.new
  end

end

编辑：

最好的，我知道如何处理这是解释我想的关系，试图实现，那么你告诉我，我要走了，我们从那里。

The best I know how to handle it is to explain what I "think" the relationships are attempting to accomplish then you tell me where I'm off and we go from there.

1），用户可以拥有许多博客

1) A User can "own" many blogs

2）一个博客可以有很多帖子

2) A blog can have many posts

3）职位属于单个用户和单个博客

3) A post belongs to a single user and to a single blog

4）博客中只能有一个老板（用户）

4) a blog can only have one "owner" (user)

5）博客可以拥有，受到了很多用户，从而使他们的权限来发布。

5) Blogs can be "owned" by many users thereby giving them permission to post.

如果1-4是真的，5假的... ...这不是一个的has_many：通过方案，或许多一对多的关系，只是一个一对多的关系。

If 1-4 are true, and 5 false... that isn't a "has_many :through" scenario or many-to-many relationship, just one-to-many relationships.

因此​​，职位不应被用作关联表。有不需要的关联表

Accordingly, posts should not be used as an association table. There isn't an association table needed.

添加 t.integer：USER_ID，：空=＆GT;假的博客表

class Blog < ActiveRecord::Base
  belongs_to :users, 
  has_many :posts, :dependent=>:destroy # rec'd error in RoR3... replaced true with :destroy
end

class User < ActiveRecord::Base
  has_many :blogs, :dependent=>:destroy
  has_many :posts
  after_create :add_blog

  private
  def add_blog
    blogs << Blog.new
  end
end

class Post < ActiveRecord::Base
  belongs_to :blog
  belongs_to :user
end

如果5是真的，这将是一个真正的多到很多......但我不认为这就是你试图做什么。

If 5 is true, this would be a true many-to-many... but I don't think that's what you're attempting to do.

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