小编Wal*_*llE的帖子

我正在尝试使用Roo将Excel电子表格中的数据导入Rails应用程序中的表(data_points).

我收到错误:

undefined method `fetch_value' for nil:NilClass

并且该错误在行引用了我的data_point.rb文件(参见下面的完整代码摘录):

data_point.save!

"应用程序跟踪"说:

app/models/data_point.rb:29:in `block in import'
app/models/data_point.rb:19:in `import'
app/controllers/data_points_controller.rb:65:in `import'

我很困惑,因为我的整个应用程序中的"查找所有"都没有显示fetch_value的实例

这是我的应用程序中的其他代码:

在我的模型中,data_point.rb:

class DataPoint < ActiveRecord::Base
attr_accessor :annual_income, :income_percentile, :years_education

def initialize(annual_income, income_percentile, years_education)
    @annual_income = annual_income
    @income_percentile = income_percentile
    @years_education = years_education
end

def self.import(file)
    spreadsheet = open_spreadsheet(file)
    header = spreadsheet.row(1)
    (2..11).each do |i| 
        annual_income = spreadsheet.cell(i, 'A')
        income_percentile = spreadsheet.cell(i, 'B')
        years_education = spreadsheet.cell(i, 'C')
        data_point = DataPoint.new(annual_income, income_percentile, years_education)
        data_point.save!
    end
end 

def self.open_spreadsheet(file)
    case File.extname(file.original_filename)
    when ".xlsx" …