ruby 没有将 nil 隐式转换为 String 错误
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no implicit conversion of nil into String error
提问by Angela Jonon
I have a ruby script that will create two files by taking and merging values from another file.
我有一个 ruby 脚本，它将通过从另一个文件中获取和合并值来创建两个文件。
#Resources
require 'rubygems'
require 'csv'
col_date = []
col_constant1 = []
col_constant2 = []
col_appYear = []
col_statsDesc = []
col_keyStats =[]
col_weeklyTotal=[]
weekly_total = []
fname = "finalStats.csv" #variable for capture file
finalStatsFile = File.open(fname, "w") #write to capture file
fname2 = "weeklyStats.csv"
weeklyStatsFile = File.open(fname2, "w")
CSV.foreach('compareData.csv', converters: :numeric) do |row|
weekly_total << row[0] - row[1]
weekly_total.each do |data|
data << weekly_total.shift
weeklyStatsFile.puts data
end
end
#retrieve stats from original document
CSV.foreach("autoCapture.csv") {|row| col_date << row[0]}
CSV.foreach("autoCapture.csv") {|row| col_constant1 << row[1]}
CSV.foreach("autoCapture.csv") {|row| col_appYear << row[2]}
CSV.foreach("autoCapture.csv") {|row| col_statsDesc << row[3]}
CSV.foreach("autoCapture.csv") {|row| col_constant2 << row[4]}
CSV.foreach("autoCapture.csv") {|row| col_keyStats << row[5]}
CSV.foreach("weeklyStats.csv") {|row| col_weeklyTotal << row[0]}
col_date.zip(col_constant1, col_appYear, col_statsDesc, col_constant2, col_keyStats, col_weeklyTotal).each do |col_date, col_constant1, col_appYear, col_statsDesc, col_constant2,
col_keyStats, col_weeklyTotal|
finalStatsFile.puts col_date+", "+col_constant1+", "+ col_appYear+", "+col_statsDesc+", "+col_constant2+", "+col_keyStats+", "+col_weeklyTotal
end
In one file I wish to subtract the values in row[1] from the values in row[0] to create a new 'weekly_total' value. I then output this array of values in a file called weeklyStats.csv. This will output a column of values fine.
在一个文件中，我希望从 row[0] 中的值中减去 row[1] 中的值以创建一个新的“weekly_total”值。然后我在一个名为weeklyStats.csv 的文件中输出这个值数组。这将输出一列值。
However, I want to join these values with another set from another file (autoCapture.csv) and when I try to zip them as arrays so that they read across in corresponding rows I get the error:
但是，我想将这些值与另一个文件 (autoCapture.csv) 中的另一组值连接起来，当我尝试将它们压缩为数组以便它们在相应的行中读取时，出现错误：
weeklyStats_csv.rb:42:in `+': no implicit conversion of nil into String (TypeError)
from weeklyStats_csv.rb:42:in `block in <main>'
from weeklyStats_csv.rb:40:in `each'
from weeklyStats_csv.rb:40:in `<main>'
I gather this means that the array zip will not catch an exception if the one of the values is nil and therefore cannot convert to string. The problem is, I have tried converting weekly_total to string and array as I thought that it may be the problem (a mismatch of types) but I just dont where to go from here. Can anyone help?
我认为这意味着如果其中一个值为零，则数组 zip 将不会捕获异常，因此无法转换为字符串。问题是，我尝试将weekly_total 转换为字符串和数组，因为我认为这可能是问题所在（类型不匹配），但我只是不知道从哪里开始。任何人都可以帮忙吗？
回答by Aleksei Matiushkin
One of (or more) values in string
字符串中的一个（或多个）值
finalStatsFile.puts col_date+", "+col_constant1+", "+ col_appYear+", "+col_statsDesc+", "+col_constant2+", "+col_keyStats+", "+col_weeklyTotal
became nil. To fix the output you should explicitly cast them to strings:
变成了nil。要修复输出，您应该将它们显式转换为字符串：
finalStatsFile.puts col_date.to_s + ", " +
col_constant1.to_s + ", " +
col_appYear.to_s + ", " +
col_statsDesc.to_s + ", " +
col_constant2.to_s + ", " +
col_keyStats.to_s + ", " +
col_weeklyTotal.to_s
BTW, the whole clause might be rewritten in more rubyish manner:
顺便说一句，整个条款可能会以更红宝石的方式重写：
finalStatsFile.puts [ col_date,
col_constant1,
col_appYear,
col_statsDesc,
col_constant2,
col_keyStats,
col_weeklyTotal ].map(&:to_s).join(', ')
