更新文本文件python中的单个字段答案

【问题标题】：Update single field in text file python更新文本文件python中的单个字段
【发布时间】：2018-09-30 22:38:40
【问题描述】：

我有这个功能：

def favourites():
name = input("Enter your name as you did when you signed up: ")
new_artist = input("Would you like to edit your favourite artist? y/n ").lower().strip()
if new_artist == 'yes' or new_artist == 'y':
    old_artist = input("Enter the favourite artist you used when signing up: ")
    artist = input("Enter your new favourite artist: ")
    usersFile = open('users.txt', 'r+')
    usersRec = usersFile.readline()
    # reads each line in the file
    while usersRec != "":
        # splits each record into fields 
        field = usersRec.split(',')
        if field[0] == name:
            usersFile.write(field[2].replace(old_artist, artist))
        usersRec = usersFile.readline()
    usersFile.close()

我已读取文本文件中的一行，然后将其拆分为多个字段，我想更新一个字段。搜索并找到了 update() 函数，所以尝试了一下，但它不起作用，我不确定我做错了什么。有什么建议吗？

【问题讨论】：

标签： python python-3.x file-handling

【解决方案1】：

您应该在另一个流中写入文件，打开文件进行写入。还对 readlines() 方法和“替换”部分进行了一些更正（您应该将结果放入变量字段 [2]）：

     import io
     import sys

def favourites():
    content=[]
    name = input("Enter your name as you did when you signed up: ")
    new_artist = input("Would you like to edit your favourite artist? y/n 
                  ").lower().strip()
    if new_artist == 'yes' or new_artist == 'y':
       old_artist = input("Enter the favourite artist you used when signing 
                     up: ")
       artist = input("Enter your new favourite artist: ")

         with open('users.txt', 'r+') as usersFile:
           usersRec = usersFile.readlines()
           print(usersRec)
# reads each line in the file
           for ur in usersRec:

    # splits each record into fields 
              field = ur.split(',')
              if field[0] == name:
                field[2] = field[2].replace(old_artist, artist)
                content.append(','.join(field))
              else: 
                content.append(','.join(field))
        usersRec = usersFile.readline()

     usersFile.close()

  writeToFile(content)


def writeToFile(content):
   with open('users.txt', 'w+') as usersFile:
      for line in content:
        usersFile.write(line)
   usersFile.close()

if __name__=="__main__":
    favourites()

【讨论】：