Multiple has_many relationships to same model

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抹茶落季
抹茶落季 2021-02-04 09:07

I have a model User that can create Posts

User
 has_many :posts
Post
 belongs_to :user

However, I want to also allow users to save posts as boo

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4条回答
  • 2021-02-04 09:12

    I did something similar to previous comments here but successfully used inverse_of to differentiate users and 'post authors':

    User
    has_many :authored_posts, class_name: 'Post', inverse_of: 'author'
    
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  • 2021-02-04 09:15

    Maybe something like this?

    User
      has_many :bookmarks
      has_many :posts, through: :bookmarks
      has_many :authored_posts, foreign_key: :author_id, class_name: 'Post'
    Bookmark
      belongs_to :post
      belongs_to :user
    Post
      belongs_to :author, class_name: 'User'
      has_many :bookmarks
      has_many :users, through: :bookmarks
    

    In this way, you are able to keep posts that are written by and bookmarked by a user separate. You could also set it up so that whenever an author creates a post, it can automatically get bookmarked by the user. i.e.

    class PostsController < ActionController::Base
      def create
        @post = @user.authored_posts.build(post_params)
        @user.posts << @post
    
        if @post.valid?
          # do good stuff
        else
          # do errors
        end
      end
    end
    

    There is a strong 1:N relationship between author and authored_posts. Then there is a weaker N:M relationship between Users and Posts using Bookmark as the join model. You can add authored posts to be bookmarked when they are created using the controller code above. Removing a bookmark on an authored post will simply remove it from the posts relationship, but not the authored_posts relationship.

    You cannot define multiple relationships using the same name.

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  • 2021-02-04 09:16

    Check the rails API on this. You should be able to specify :as and :source

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  • 2021-02-04 09:34

    How do you get around this problem?

    By giving your associations unique names. It's not that you can't unambiguously access them, it's that your second one is destroying the first one.

    Instead of calling both posts, use bookmarked_posts for your second association:

    has_many :bookmarked_posts, through: :bookmarks, source: :posts
    
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