Question

I have several tables, let s say for example: articles, thoughts and pages and I want to be able to add comments for each one of them. Should I add comments tables for each on of the table (articles_comments,pages_comments...) or somehow do general comments table for all kinds of data (plz extend how to implement that in rails if you can)

我有这样的想法,即发表载有评论的表格。

[COMMENTS] ID, MODEL, MODEL_ID, USER_ID, TEXT

while model contain the destination table(articles/posts...) and model_id the foreign id in the table, is it good solution? the problem is that I have no idea how to implement such model in rails.

I also would like to know how Facebook implemented their posts db. fb user can post any kind of data (question/status/poll/picture) and it s just fit in the feeds table with current order and comments.

Answer 1

形成一个一般的<条码>Comment模型,使之与这种模型一样多变:

class Comment < ActiveRecord::Base
  belongs_to :commentable, :polymorphic => true
end

class Article < ActiveRecord::Base
  has_many :comments, :as => :commentable
end

class Thought < ActiveRecord::Base
  has_many :comments, :as => :commentable
end

根据<条码>第模式的事例,您可检索以下意见汇编:@article.comments。

如果您有<条码>Comment模型,你可以通过<条码>@comment.commentable将其带至母。

为了开展这项工作,你需要宣布模型中一个外国关键栏和一个称为多形态界面的类别栏:

class CreateComments < ActiveRecord::Migration
  def self.up
    create_table :comments do |t|
      t.text       :content
      t.references :user
      t.references :commentable, :polymorphic => true
      t.timestamps
    end
  end

  def self.down
    drop_table :comments
  end
end

Answer 2

I suspect that "articles", "thoughts" and "pages" are more alike than unalike, and perhaps should be in one table. Then this question goes away.

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