通过ajax在rails中显示警报消息

Question

我需要知道如何通过javascript显示在rails中创建帖子的验证错误消息

我正在使用 remotipart gem 异步上传图片

后模型是

class Post < ActiveRecord::Base
  belongs_to :topic
  has_many :comments
  has_many :ratings
  belongs_to :user
  has_and_belongs_to_many :users , join_table: :posts_users_read_status
  has_and_belongs_to_many :tags
  has_attached_file :image
  validates_presence_of :name, :presence => true
  validates_attachment_size :image, :less_than => 1.megabytes
  validates_attachment_content_type :image, :content_type => ["image/jpg", "image/jpeg", "image/png", "image/gif"]
  validates_length_of :name,:maximum => 20

end

验证是名称不应超过 20 个字符

我正在我的索引页面中呈现表单

帖子的索引是

<p id="notice"><%= notice %></p>
<style>
table, th, td {
    border: 1px solid black;
    border-collapse: collapse;

}
th, td {
    padding: 5px;
text-align: center;
}
</style>
<h1>Listing Posts</h1>
<table style='width:100%' id="posts">
  <thead>
    <tr>
      <th>Name</th> 
      <th>Email</th>
      <th>Message</th>
      <th>Topic</th>
      <th>Status</th>
      <th>No of<br> comments</th>
      <th colspan="3">Edit_options</th>
    </tr>
  </thead>
  <tbody>

    <%= render @posts%>

  </tbody>
</table>

<br>
<%= will_paginate @posts%>
<% if @topic %>
<%= link_to 'New Post', "#" ,id: "posts-link"%> |
    <section id ="new-posts">
<%= render 'form'%>
    </section>
<%= link_to 'Back to Topics', topic_path(@topic) %>
<% else %>
<%= link_to 'Topics', topics_path %>
<%end%>

创建帖子的javascript是

<%if @posts.save%>
$("#posts").append('<%= j render @posts%>');
alert("Post Created")
$("#post_name").val("")
$("#post_message").val("")
<%else%>
alert(<%=@posts.save!%>)
<%end%>

当我给出超过 20 个字符的名称时，我需要在使用控制台时显示错误消息，我可以通过 .save 来显示它！ 但它不适用于 javascript

请任何人帮助我...！

Answer 1

我怀疑您使用的是以下模式：

#app/controllers/posts_controller.rb
class PostsController < ApplicationController
   respond_to :js, only: :create

   def create
      @post = Post.new post_params
      @post.save
   end 
end

#app/views/posts/create.js.erb
<% if @post.save %>
    alert("Post Created");
    $("#posts").append("<%=j render @post %>"); // make sure you have the partial for this
    $("#post_name").val("");
    $("#post_message").val("");
<% else %>
    <% if @post.errors.any? %>
        <% @post.errors.each do |name,message| %>
           $("#<%=j name %>").append(<%=j message %>);
        <% end %>
    <% end %>
<% end %> 

---

您真的应该在某种程度上修复您的 Post 模型：

#app/models/post.rb
class Post < ActiveRecord::Base
  has_many :comments
  has_many :ratings
  belongs_to :user
  belongs_to :topic

  has_and_belongs_to_many :users , join_table: :posts_users_read_status
  has_and_belongs_to_many :tags

  has_attached_file :image

  validates :name, presence: true, length: { maximum: 20 }
  validates_attachment :image, presence: true,
     content_type: { content_type: ["image/jpg", "image/jpeg", "image/png", "image/gif"] },
     size:         { less_than: 1.megabytes }

end

Ref 用于回形针验证