title: Undefined method `user_id=' for #<Comment
body: <p>I trying to create app, with 3 model user, posts and comment.They 3 models 
  associated "has_many" and "belongs_to" associations.But I did not get do that would have been comments from the user, how to do it?</p>
  
  <p>controller comments_controller.Here browser show an error in 5 line (Undefined method `user_id=' for #
  
  <pre><code>class CommentsController &lt; ApplicationController
    def create
      @post = Post.find(params[:post_id])
      @comment = @post.comments.create(comment_params)
      @comment.user_id = current_user.id
      redirect_to post_path(@post)
    end
  
    private
      def comment_params
        params.require(:comment).permit(:body)
      end
  end
  </code></pre>
  
  <p>model comment.rb</p>
  
  <pre><code>class Comment &lt; ActiveRecord::Base
    belongs_to :post
    belongs_to :user
  end
  </code></pre>
  
  <p>model user.rb</p>
  
  <pre><code>class User &lt; ActiveRecord::Base
  has_many :posts
  has_many :comments
  end
  </code></pre>
  
  <p>model post.rb</p>
  
  <pre><code>class Post &lt; ActiveRecord::Base
      belongs_to :user
      has_many :comments
  end
  </code></pre>
  
  <p>shema.rb</p>
  
  <pre><code>ActiveRecord::Schema.define(version: 20141114150704) do
  
    create_table "comments", force: true do |t|
      t.text     "body"
      t.integer  "post_id"
      t.datetime "created_at"
      t.datetime "updated_at"
    end
  
    add_index "comments", ["post_id"], name: "index_comments_on_post_id"
  
    create_table "posts", force: true do |t|
      t.string   "title"
      t.text     "text"
      t.datetime "created_at"
      t.datetime "updated_at"
    end
  
    create_table "users", force: true do |t|
      t.string   "name"
      t.string   "email"
      t.datetime "created_at"
      t.datetime "updated_at"
      t.string   "password_digest"
      t.string   "remember_token"
    end
  
    add_index "users", ["remember_token"], name: "index_users_on_remember_token"
  
  end
  </code></pre>
  
  <p><strong>UPD</strong>
  full error trace</p>
  
  <pre><code>app/controllers/comments_controller.rb:5:in `create'
  actionpack (4.1.6) lib/action_controller/metal/implicit_render.rb:4:in `send_action'
  actionpack (4.1.6) lib/abstract_controller/base.rb:189:in `process_action'
  actionpack (4.1.6) lib/action_controller/metal/rendering.rb:10:in `process_action'
  actionpack (4.1.6) lib/abstract_controller/callbacks.rb:20:in `block in process_action'
  activesupport (4.1.6) lib/active_support/callbacks.rb:113:in `call'
  activesupport (4.1.6) lib/active_support/callbacks.rb:113:in `call'
  activesupport (4.1.6) lib/active_support/callbacks.rb:229:in `block in halting'
  activesupport (4.1.6) lib/active_support/callbacks.rb:229:in `call'
  activesupport (4.1.6) lib/active_support/callbacks.rb:229:in `block in halting'
  activesupport (4.1.6) lib/active_support/callbacks.rb:166:in `call'
  activesupport (4.1.6) lib/active_support/callbacks.rb:166:in `block in halting'
  activesupport (4.1.6) lib/active_support/callbacks.rb:166:in `call'
  activesupport (4.1.6) lib/active_support/callbacks.rb:166:in `block in halting'
  activesupport (4.1.6) lib/active_support/callbacks.rb:166:in `call'
  activesupport (4.1.6) lib/active_support/callbacks.rb:166:in `block in halting'
  activesupport (4.1.6) lib/active_support/callbacks.rb:86:in `call'
  activesupport (4.1.6) lib/active_support/callbacks.rb:86:in `run_callbacks'
  actionpack (4.1.6) lib/abstract_controller/callbacks.rb:19:in `process_action'
  actionpack (4.1.6) lib/action_controller/metal/rescue.rb:29:in `process_action'
  actionpack (4.1.6) lib/action_controller/metal/instrumentation.rb:31:in `block in process_action'
  activesupport (4.1.6) lib/active_support/notifications.rb:159:in `block in instrument'
  activesupport (4.1.6) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
  activesupport (4.1.6) lib/active_support/notifications.rb:159:in `instrument'
  actionpack (4.1.6) lib/action_controller/metal/instrumentation.rb:30:in `process_action'
  actionpack (4.1.6) lib/action_controller/metal/params_wrapper.rb:250:in `process_action'
  activerecord (4.1.6) lib/active_record/railties/controller_runtime.rb:18:in `process_action'
  actionpack (4.1.6) lib/abstract_controller/base.rb:136:in `process'
  actionview (4.1.6) lib/action_view/rendering.rb:30:in `process'
  actionpack (4.1.6) lib/action_controller/metal.rb:196:in `dispatch'
  actionpack (4.1.6) lib/action_controller/metal/rack_delegation.rb:13:in `dispatch'
  actionpack (4.1.6) lib/action_controller/metal.rb:232:in `block in action'
  actionpack (4.1.6) lib/action_dispatch/routing/route_set.rb:82:in `call'
  actionpack (4.1.6) lib/action_dispatch/routing/route_set.rb:82:in `dispatch'
  actionpack (4.1.6) lib/action_dispatch/routing/route_set.rb:50:in `call'
  actionpack (4.1.6) lib/action_dispatch/journey/router.rb:73:in `block in call'
  actionpack (4.1.6) lib/action_dispatch/journey/router.rb:59:in `each'
  actionpack (4.1.6) lib/action_dispatch/journey/router.rb:59:in `call'
  actionpack (4.1.6) lib/action_dispatch/routing/route_set.rb:678:in `call'
  rack (1.5.2) lib/rack/etag.rb:23:in `call'
  rack (1.5.2) lib/rack/conditionalget.rb:35:in `call'
  rack (1.5.2) lib/rack/head.rb:11:in `call'
  actionpack (4.1.6) lib/action_dispatch/middleware/params_parser.rb:27:in `call'
  actionpack (4.1.6) lib/action_dispatch/middleware/flash.rb:254:in `call'
  rack (1.5.2) lib/rack/session/abstract/id.rb:225:in `context'
  rack (1.5.2) lib/rack/session/abstract/id.rb:220:in `call'
  actionpack (4.1.6) lib/action_dispatch/middleware/cookies.rb:560:in `call'
  activerecord (4.1.6) lib/active_record/query_cache.rb:36:in `call'
  activerecord (4.1.6) lib/active_record/connection_adapters/abstract/connection_pool.rb:621:in `call'
  activerecord (4.1.6) lib/active_record/migration.rb:380:in `call'
  actionpack (4.1.6) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
  activesupport (4.1.6) lib/active_support/callbacks.rb:82:in `run_callbacks'
  actionpack (4.1.6) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
  actionpack (4.1.6) lib/action_dispatch/middleware/reloader.rb:73:in `call'
  actionpack (4.1.6) lib/action_dispatch/middleware/remote_ip.rb:76:in `call'
  actionpack (4.1.6) lib/action_dispatch/middleware/debug_exceptions.rb:17:in `call'
  actionpack (4.1.6) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
  railties (4.1.6) lib/rails/rack/logger.rb:38:in `call_app'
  railties (4.1.6) lib/rails/rack/logger.rb:20:in `block in call'
  activesupport (4.1.6) lib/active_support/tagged_logging.rb:68:in `block in tagged'
  activesupport (4.1.6) lib/active_support/tagged_logging.rb:26:in `tagged'
  activesupport (4.1.6) lib/active_support/tagged_logging.rb:68:in `tagged'
  railties (4.1.6) lib/rails/rack/logger.rb:20:in `call'
  actionpack (4.1.6) lib/action_dispatch/middleware/request_id.rb:21:in `call'
  rack (1.5.2) lib/rack/methodoverride.rb:21:in `call'
  rack (1.5.2) lib/rack/runtime.rb:17:in `call'
  activesupport (4.1.6) lib/active_support/cache/strategy/local_cache_middleware.rb:26:in `call'
  rack (1.5.2) lib/rack/lock.rb:17:in `call'
  actionpack (4.1.6) lib/action_dispatch/middleware/static.rb:64:in `call'
  rack (1.5.2) lib/rack/sendfile.rb:112:in `call'
  railties (4.1.6) lib/rails/engine.rb:514:in `call'
  railties (4.1.6) lib/rails/application.rb:144:in `call'
  rack (1.5.2) lib/rack/lock.rb:17:in `call'
  rack (1.5.2) lib/rack/content_length.rb:14:in `call'
  rack (1.5.2) lib/rack/handler/webrick.rb:60:in `service'
  /home/weare138/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/webrick/httpserver.rb:138:in `service'
  /home/weare138/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/webrick/httpserver.rb:94:in `run'
  /home/weare138/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/webrick/server.rb:295:in `block in start_thread'
  </code></pre>
  
  <p>sorry for my bad English</p>