Ruby on Rails

File Upload

The following code example illustrates how to handle file upload on your server using Ruby as a server-side language. For step by step explanation of the upload flow see file upload concept.

Frontend

The main index page.

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">

  <!-- Include Editor style. -->
  <link href="https://cdn.jsdelivr.net/npm/froala-editor@3.0.0-beta.1/css/froala_editor.pkgd.min.css" rel="stylesheet" type="text/css" />
</head>

<body>
  <!-- Include Editor JS files. -->
  <script type="text/javascript" src="https://cdn.jsdelivr.net/npm/froala-editor@3.0.0-beta.1//js/froala_editor.pkgd.min.js"></script>
  <div class="sample">
    <h2>File upload example.</h2>
    <form>
      <textarea id="edit" name="content"></textarea>
    </form>
  </div>

  <!-- Initialize the editor. -->
  <script>
    new FroalaEditor('#edit', {
      // Set the file upload URL.
      fileUploadURL: '/upload_file',

      fileUploadParams: {
        id: 'my_editor'
      }
    })
  </script>
</body>
</html>

Backend

upload_controller.rb file will manage the upload part. It has basic file format validations this can be easily extended.

The uploads directory will be automatically created if it dose not exist under public/uploads/files

After processing the uploaded file, if it passes the validation, the server will respond with a JSON object containing a link to the uploaded file.

E.g.: {"link":"http://server_address/download_file/name_of_file"}.

class UploadController < ActionController::Base

  FILE_EXT = [".txt", ".pdf", ".doc"]

  def upload_file
    if params[:file]
      FileUtils::mkdir_p(Rails.root.join("public/uploads/files"))

      ext = File.extname(params[:file].original_filename)
      ext = file_validation(ext)
      file_name = "#{SecureRandom.urlsafe_base64}#{ext}"
      path = Rails.root.join("public/uploads/files/", file_name)

      File.open(path, "wb") {|f| f.write(params[:file].read)}
      view_file = Rails.root.join("/download_file/", file_name).to_s
      render :json => {:link => view_file}.to_json

    else
      render :text => {:link => nil}.to_json
    end
  end

  def file_validation(ext)
    raise "Not allowed" unless FILE_EXT.include?(ext)
  end

  def access_file
    if File.exists?(Rails.root.join("public", "uploads", "files", params[:name]))
      send_data File.read(Rails.root.join("public", "uploads", "files", params[:name])), :disposition => "attachment"
    else
      render :nothing => true
    end
  end
end

routes.rb file will manage the routing part.

Inside this file you need to define the routes for the POST file upload and the GET uploaded file requests

Rails.application.routes.draw do
# For details on the DSL available within this file, see http://guides.rubyonrails.org/routing.html

post "/upload_file" => "upload#upload_file", :as => :upload_file
get "/download_file/:name" => "upload#access_file", :as => :upload_access_file, :name => /.*/