Ruby 无法将图表添加到Excel工作簿

Ruby 无法将图表添加到Excel工作簿,ruby,excel,charts,rubygems,Ruby,Excel,Charts,Rubygems,我正在使用writeexcelgem 以下是我的代码片段: workbook = WriteExcel.new("graphTest.xls") worksheet = workbook.add_worksheet(sheetname = "Test") chart = workbook.add_chart( :type => "Chart::column", :name => "Chart", :embedded => 1 ) 我得到以下错误: nil的

我正在使用
writeexcel
gem

以下是我的代码片段:

workbook = WriteExcel.new("graphTest.xls")

worksheet = workbook.add_worksheet(sheetname = "Test")

chart = workbook.add_chart(
  :type => "Chart::column",
  :name => "Chart",
  :embedded => 1
  )
我得到以下错误:

nil的未定义方法“new”:NilClass(NoMethodError)

完全错误:

/Users/guy/.rvm/gems/ruby-2.3.0/gems/writeexcel-1.0.5/lib/writeexcel/chart.rb
:79:in 'factory': undefined method 'new' for nil:NilClass (NoMethodError)
        from /Users/guy/.rvm/gems/ruby-2.3.0/gems/writeexcel-1.0.5/lib/writee
xcel/workbook.rb:334:in 'add_chart'
        from excelGraph.rb:18:in '<main>'
/Users/guy/.rvm/gems/ruby-2.3.0/gems/writeexcel-1.0.5/lib/writeexcel/chart.rb
:79:在“工厂”中:nil:NilClass(NoMethodError)的未定义方法“new”
来自/Users/guy/.rvm/gems/ruby-2.3.0/gems/writeexcel-1.0.5/lib/writee
xcel/workbook.rb:334:在“添加图表”中
从excelGraph.rb:18:in''
如果我直接从找到的gem文档中选取一个示例,为什么会收到此错误消息?

在代码段中找到的“Gotcha”是
图表中
列的大小写:

chart = workbook.add_chart(
  :type => "Chart::Column", #capitalized
  :name => "Chart",
  :embedded => 1
  )
而不是

chart = workbook.add_chart(
  :type => "Chart::column", #all lowercase
  :name => "Chart",
  :embedded => 1
  )

这里的示例代码有效,刚刚测试过。上面提到的图表示例可以找到。