Rails:上传文件

Question

我正试着跟随本教程。它是用以前版本的Rails编写的，我使用的是Rails 4。我试图上传文件，但是我得到了以下错误：

NoMethodError in UploadController#uploadfile
undefined method `[]' for nil:NilClass

Extracted source (around line #3):

class DataFile < ActiveRecord::Base
  def self.save(upload)
    name =  upload['datafile'].original_filename
    directory = "public/data"
    # create the file path
    path = File.join(directory, name)

Rails.root: C:/Ruby193/mylibrary

Application Trace | Framework Trace | Full Trace
app/models/data_file.rb:3:in `save'
app/controllers/upload_controller.rb:6:in `uploadfile'

这是data_file.rb

class DataFile < ActiveRecord::Base
  def self.save(upload)
    name =  upload['datafile'].original_filename
    directory = "public/data"
    # create the file path
    path = File.join(directory, name)
    # write the file
    File.open(path, "wb") { |f| f.write(upload['datafile'].read) }
  end
end

这是控制器upload_controller.rb

class UploadController < ApplicationController
  def index
    render :file => 'app\views\upload\uploadfile.html'
  end
  def uploadfile
    post = DataFile.save(params[:upload])
    render :text => "File has been uploaded successfully"
  end
end

这是uploadfile.html

<h1>File Upload</h1>
<%= form_tag({:action => 'uploadfile'}, :multipart => true) do %>
<p><label for="upload_file">Select File</label>
    <%= file_field 'upload', 'datafile' %></p>
<%= submit_tag "Upload" %>
<% end %>

我该怎么办？提前感谢

Answer 1

它看起来像平面图:上传不是你想的那样。您忘记将表单设置为多部分。如果修复不起作用，就开始检查params，看看你实际得到了什么。

def uploadfile
  puts params.inspect # Add this line to see what's going on
  post = DataFile.save(params[:upload])
  render :text => "File has been uploaded successfully"
end

而且，这不是一个很好的“答案”，但我在使用回形针处理文件上传方面取得了很好的成功。如果你只想要一些有用的东西(而不是自己学习)，那就去看看吧。