为什么我的 Rails Show 操作在选择后会创建新记录？

Question

Rails nooby，所以我不知道要提供什么信息。基本上，当我的显示操作从图片控制器调用时，就会插入新的评论记录。我的输出如下所示：

Started GET "/pictures/2" for 127.0.0.1 at Wed Oct 19 18:43:24 -0400 2011
  Processing by PicturesController#show as HTML
  Parameters: {"id"=>"2"}
  Picture Load (0.2ms)  SELECT "pictures".* FROM "pictures" WHERE "pictures"."id" = $1     LIMIT 1  [["id", "2"]]
  Comment Load (0.4ms)  SELECT "comments".* FROM "comments" WHERE "comments"."picture_id"     = 2
   (0.2ms)  BEGIN
  SQL (0.7ms)  INSERT INTO "comments" ("comment", "created_at", "downvote", "picture_id",     "updated_at", "upvote") VALUES ($1, $2, $3, $4, $5, $6) RETURNING "id"  [["comment", nil],     ["created_at", Wed, 19 Oct 2011 22:43:24 UTC +00:00], ["downvote", nil], ["picture_id", 2],     ["updated_at", Wed, 19 Oct 2011 22:43:24 UTC +00:00], ["upvote", nil]]
   (1.1ms)  COMMIT
Rendered pictures/show.html.erb within layouts/application (32.2ms)
Completed 200 OK in 51ms (Views: 41.0ms | ActiveRecord: 7.5ms)

显示控制器：

def show
  @picture = Picture.find(params[:id])
  @comments = @picture.comments
  respond_to do |format|
    format.html # show.html.erb
    format.json { render :json => @picture }
  end
end

显示视图：

<p id="notice"><%= notice %></p>

<h2><%= @picture.title %></h2> <br />
    <ul class="media-grid">
     <li>
     <a href="#">
     <%= image_tag @picture.url %>
    </a>
    </li>
  </ul>
<table>
<% @comments.each do |comment| %>
  <tr>
    <td><%= comment.comment %></td>
<td><%= comment.upvote %></td>
<td><%= comment.downvote %></td>
</tr>
<% end %>
</table>
<%= form_for [@picture, @picture.comments.create] do |f| %>
  <%= f.label "Comment:" %><br />
  <%= f.text_field :comment %>
  <%= f.submit %>
<% end %>

<%= link_to 'Back', pictures_path %>

模型：

class Comment < ActiveRecord::Base
  belongs_to :picture
end

class Picture < ActiveRecord::Base
  has_many :comments
end

Answer 1

据我所知，你不想使用

<%= form_for [@picture, @picture.comments.create] do |f| %>

但是

<%= form_for [@picture, @picture.comments.new] do |f| %>