Rails User Comments on Movies

问题:

I have three scaffolds Users, Comments and Movies

In my app, I want Users to Comment on Movies, and different users can Comment on a Movie page.

How would i create the associations code that lets users add comments on movies and then on the movie page display all comments? COuld you please also tell me the code to count the comments, so show how many comments there are and display them in integers

What i've got so far

Comments table with Subject and Body Movies table Users table

user.rb

has_many: comments

movies.rb

has_many: comments

comments.rb

belongs_to :users
belongs_to :movies

Thanks !

回答1:

The associations you would need is to tell what they belong to. so you would need to do the following in the models:

Comment Model:

class Comment < ActiveRecord::Base
  belongs_to :user
  belongs_to :movie
end

User Model:

class User < ActiveRecord::Base
  has_many :comments
end

Movie Model:

class Movie < ActiveRecord::Base
  has_many :comments
end

You would need to generate migrations to add the foreign key columns to the comment table. Once you have that, all you need to do is attach the comments to the movies and users through their id. Then to have them the comments display, in the view:

<% @movie.comments.each do |comment| %>
  <%= comment.text %>
<% end %>

EDIT: To create a comment, you would need a link to add a new comment. in the view:

<%= link_to 'New Comment', new_movie_comment_path(@movie) %>

That should take you to the new comment view and the form for it. In the form, you can associate the comment to the user by setting a hidden field that associates the user to the comment. In the comment form view:

<%= form_for(@comment) do |f| %>
  <%= f.label :user %>
  <%= f.hidden_field :comment, :user_id, current_user_id %>
<% end %>

The last part assumes you have a session active.

EDIT 2:

In the routes, you would nest the comments resource inside the movies resource:

resources :movies do
  resources :comments
end

EDIT 3:

In your comments controller, you'll have to point the actions to the movie. In the controller

class CommentsController < ApplicationController
  before_filter :load_movie

  private
    def load_movie
      @movie = Movie.find(params[:movie_id])
    end

The private section needs to be at the bottom of the controller. With that done, update the actions to use the @movie.

def index
  @comments = @movie.comments.all
end

Do that for show, new, etc actions in the controller. In the create action and update action, you'll need to update the html redirect.

format.html { redirect_to (@movie, @comment), notice: 'Comment was successfully created.' }

and

format.html { redirect_to (@movie, @comment), notice: 'Comment was successfully Updated.' }

回答2:

In users.rb

has_many :movies, through: :comments

In movies.rb

has_many :users, through: comments

This is called a has-many-through association. Reference here.

To count:

number_of_comments = Comment.all.size
number_of_comments_on_a_movie = Movie.find(movie_id).comments.size
number_of_comments_by_a_user = User.find(user_id).comments.size

回答3:

You may have :

class User < ActiveRecord::Base
  has_many :comments, :dependent => :destroy
end

class Comment< ActiveRecord::Base
  belongs_to :user
  belongs_to :movie
end

class Movies< ActiveRecord::Base
  has_many :comments, :dependent => :destroy
end

In yours views you can do something like :

Number of comments : <%= @movie.comments.length %>
<% @movie.comments.each do |comment| %>
  Pseudo : <%= comment.user.pseudo%>
  Body : <%= comment.body %>
<% end %>

If you start with Rails you should take a look at this tutorial. It's awesome for basics ;)