如何验证"file_fields"在铁轨3 [英] How to validate "file_fields" in rails 3

问题描述

我是Rails的新手，请引导我.

i am a newbie for rails, please guide me.

我想验证"file_field"用于图像上传. 只能上传jpg/png/gif，并且可以上传特定尺寸，例如最大尺寸(500x500)

i want to validate "file_field" for image upload. just jpg/png/gif can be upload and specific size like max size (500x500)

这是我的_form.html.erb

this is my _form.html.erb

<%= form_for(@photo, :html => {:multipart => true} ) do |f| %>
<% if @photo.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(@photo.errors.count, "error") %> prohibited this photo from being saved:</h2>

  <ul>
  <% @photo.errors.full_messages.each do |msg| %>
    <li><%= msg %></li>
  <% end %>
  </ul>
</div>
<% end %>

<div class="field">
<%= f.label :title %><br />
<%= f.text_field :title %>
</div>
<div class="field">
<%= f.label :description %><br />
<%= f.text_area :description, :size => '115x20' %>
</div>
<div class="field">
<label for="image_file">File</label><br />
<%= file_field 'upload', 'datafile'%>
</div>
<div class="actions">
<%= f.submit %>
</div>
<% end %> 

我试图像这样进行验证

class Photo < ActiveRecord::Base
validates_presence_of :title, :description, :upload
validates_uniqueness_of :title

validates_format_of :upload, :allow_blank => false,
                  :with    => %r{\.(gif|jpg|png)$}i,
                  :message => 'must be a URL for GIF, JPG ' +
                              'or PNG image.'
end

错误就这样

undefined method `upload' for #<Photo:0xad6b294>

我错过了什么吗?

推荐答案

如果您使用任何照片上传插件，都会发现使用它的validates方法

if you are using any photo upload plugin, you will find validates methods with it

例如，使用papaerclip.您会发现

for example ,using papaerclip. you will find

validates_attachment_size :upload, :less_than => 2.megabytes

并更改您的代码

<%= file_field 'upload', 'datafile'%> to <%= f.file_field :upload, 'datafile'%>

这篇关于如何验证"file_fields"在铁轨3的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！