在 rails 中导入 csv 文件时出现未初始化常量 Student::Roo 错误

Question

我有一个应用程序，我想在该应用程序上提供从 CSV 和 Excel 文件格式导入记录的功能。我为此使用 roo gem，但在导入时出现错误 "uninitialized constant Student::Roo".

这是代码：

student.rb

def self.import(file)
  spreadsheet = open_spreadsheet(file)
  header = spreadsheet.row(1)
  (2..spreadsheet.last_row).each do |i|
    row = Hash[[header, spreadsheet.row(i)].transpose]
    product = find_by_id(row["id"]) || new
    product.attributes = row.to_hash.slice(*accessible_attributes)
    product.save!
  end
end


def self.open_spreadsheet(file)
  case File.extname(file.original_filename)
  when ".csv" then Roo::Csv.new(file.path, nil, :ignore)
  when ".xls" then Roo::Excel.new(file.path, nil, :ignore)
  when ".xlsx" then Roo::Excelx.new(file.path, nil, :ignore)
  else raise "Unknown file type: #{file.original_filename}"
  end
end

student_controller.rb :

def import
    Student.import(params[:file])
    #puts @session[:current_organization_id].inspect
    redirect_to students_path, notice: "Record imported Successfully."
  end

new.html.erb :

<%= form_tag import_students_path, multipart: true do %>
        <%= file_field_tag :file , :required=> true%> <br/>
        <%= submit_tag "Import" , :class => "btn btn-primary btn-block" %>
<% end %>

宝石文件：

source 'https://rubygems.org'
gem 'rails', '4.2.0'
gem 'mysql2'
gem 'sass-rails', '~> 5.0'
gem 'uglifier', '>= 1.3.0'
gem 'coffee-rails', '~> 4.1.0'
gem 'therubyracer', platforms: :ruby
gem 'jquery-rails'
gem 'jbuilder', '~> 2.0'
gem 'sdoc', '~> 0.4.0', group: :doc
gem 'sass', '3.2.19'
gem 'bower-rails'
gem 'font-awesome-sass'
gem 'devise'
gem 'roo'
group :development, :test do
    gem "rspec-rails", "~> 2.0"
    gem "factory_girl_rails", "~> 4.0"
    gem "capybara"
    gem "database_cleaner"
    gem "selenium-webdriver"
end

student.csv : 这是学生的测试数据。

enrollment_no,roll_no,address,father_name
11,21,test,test
17,21,test,test
18,21,test,test
19,21,test,test
20,21,test,test
22,21,test,test
23,21,test,test
24,21,test,test

Answer 1

首先，@SKV 评论后：CSV class 的正确名称是 Roo::CSV 而不是 Roo::Csv.

如果错误仍然存在，则意味着 Roo class 中的任何一个（Roo::CSV、Roo::Excel 等）在此时未定义Studentclass。这可能意味着，虽然您可能将 roo gem 添加到您的 Gemfile 并捆绑，但您需要 require roo 在任何您想要使用 gem 的地方。 gem docs.

中提到了这一点

将 require 'roo' 添加到 student.rb 文件的顶部，它应该可以正常工作：

# student.rb
require 'roo'  # <==== 

class Student < ActiveRecord::Base
  def self.open_spreadsheet(file)
    ...
  end
end

Answer 2

不是 Roo::Csv，是 Roo::CSV。所以代码应该像

def self.open_spreadsheet(file)
  case File.extname(file.original_filename)
  when ".csv" then Roo::CSV.new(file.path, nil, :ignore)
  when ".xls" then Roo::Excel.new(file.path, nil, :ignore)
  when ".xlsx" then Roo::Excelx.new(file.path, nil, :ignore)
  else raise "Unknown file type: #{file.original_filename}"
  end
end

顺便说一句，不需要做 require 'roo'

在 rails 中导入 csv 文件时出现未初始化常量 Student::Roo 错误

Getting uninitialized constant Student::Roo error while importing csv file in rails

ruby-on-rails-4

roo-gem