Question

我刚开始学习rails。我正在尝试创建一个页面来显示评论/内容以及添加评论。这就是我的更新控制器的样子：

  def update_memo
    @article = Article.find_by_id(params[:id])
    @article.update_attributes(:memo => params[:remark])
    redirect_to :back
  end

这就是我的表格：

<%= form_for @article.memo, url: {action: "update_memo", id: @article.id},  html: {method: "put"} do |f| %>
  <%= f.label :'Comment:' %>
  <%= f.text_field :remark %>
  <%= f.submit "Save !"%>
<%  end %>

第一次更新备忘录字段时很好。但是当我再次尝试更新时。它显示“Mysql2 :: Error：Column'备忘录'不能为空”

Started PUT "/showarticle/update_memo?id=1" 
Processing by ShowarticleController#update_memo as HTML
Parameters: {"utf8"=>"‚ì", "authenticity_token"=>"LXEUxk>wI9W+VpAP+mpULojiGeYTDoSBIjrCkkA3GacYwZLZyJyfHFOsoxwdSS5LUoQDuP3FGidopp2KA==", "test1"=>{"remark"=>"test0"}, "commit"=>"Save !", "id"=>"1"}
Article Load (1.8ms)  SELECT  `articles`.* FROM `articles` WHERE `articles`.`id` = 1 LIMIT 1
   (1.5ms)  BEGIN
SQL (3.5ms)  UPDATE `articles` SET `memo` = NULL WHERE `articles`.`id` = 1
Mysql2::Error: Column 'memo' cannot be null: UPDATE `articles` SET `memo` = NULL WHERE `articles`.`id` = 1
   (1.5ms)  ROLLBACK
Completed 500 Internal Server Error in 14ms (ActiveRecord: 8.3ms)

Answer 1

将文章对象传递给form_for帮助程序：

<%= form_for @article, url: {action: "update_memo", id: @article.id},  html: {method: "put"} do |f| %>
  <%= f.label :'Comment:' %>
  <%= f.text_field :memo %>
  <%= f.submit "Save !"%>
<%  end %>

你的控制者的行动：

def update_memo
  @article = Article.find_by_id(params[:id])
  @article.update_attributes(:memo => params][:article][:memo])
  redirect_to :back
end

我建议你阅读一下strong_parameters（http://api.rubyonrails.org/classes/ActionController/Parameters.html）

Answer 2

这样做：

#config/routes.rb
resources :articles do
   resources :memos #-> url.com/articles/:article_id/memos/new
end

#app/controllers/memos_controller.rb
class MemosController < ApplicationController
   def new
      @article = Article.find params[:article_id]
      @memo = @article.memos.new
   end

   def create
      @article = Article.find params[:article_id]
      @memo = @article.memos.new memo_params
      @memo.save
   end

   private

   def memo_params
      params.require(:memo).permit(:article_id, :remark)
   end
end

#app/views/memos/new.html.erb
<%= form_for @memo do |f| %>
   <%= f.text_field :remark %>
   <%= f.submit %>
<% end %>

ruby on rails form params在更新操作时变为null

2 个答案: