Python错误集锦：csv模块写入记录提示ValueError: dict contains fields not in fieldnames: ‘age’

原文链接：http://www.juzicode.com/python-error-csv-valueerror-dict-contains-fields-not-in-fieldnames

错误提示：

csv模块写入记录提示ValueError: dict contains fields not in fieldnames: ‘age’

#juzicode.com/vx:桔子code
import csv
with open('test.csv','w',encoding='utf8',newline='') as f:
    headers = ['sn','name']
    writer = csv.DictWriter(f,headers)
    writer.writeheader()
    record={'sn':'1','name':'juzicode','age':'25'}
    writer.writerow(record)

==========运行结果：
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-1-b5e7edcc4478> in <module>
      6     writer.writeheader()
      7     record={'sn':'1','name':'juzicode','age':'25'}
----> 8     writer.writerow(record)

d:\python\python38\lib\csv.py in writerow(self, rowdict)
    152 
    153     def writerow(self, rowdict):
--> 154         return self.writer.writerow(self._dict_to_list(rowdict))
    155 
    156     def writerows(self, rowdicts):

d:\python\python38\lib\csv.py in _dict_to_list(self, rowdict)
    147             wrong_fields = rowdict.keys() - self.fieldnames
    148             if wrong_fields:
--> 149                 raise ValueError("dict contains fields not in fieldnames: "
    150                                  + ", ".join([repr(x) for x in wrong_fields]))
    151         return (rowdict.get(key, self.restval) for key in self.fieldnames)

ValueError: dict contains fields not in fieldnames: 'age'

错误原因：

1、第8行写入的内容包含了3列，但是第4行定义的head只有2列，写入的列数多于head包含的列数。

解决方法：

1、需要修改head列数，适配要写入的内容的列数，这里需要将第 4行的内容增加一个元素：

#juzicode.com/vx:桔子code
import csv
with open('test.csv','w',encoding='utf8',newline='') as f:
    headers = ['sn','name','age']#添加第3个head元素
    writer = csv.DictWriter(f,headers)
    writer.writeheader()
    record={'sn':'1','name':'juzicode','age':'25'}
    writer.writerow(record)

运行结果：

扩展内容：

1. Python进阶教程m2c–csv文件

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