Question

我正在开发一个程序，并试图实现以下功能。

添加新学生
根据ID删除学生

这是我的代码

from csv import writer
import csv

def add(file_name, list_of_elem):
    # Open file in append mode
    with open(file_name, 'a+', newline='') as write_obj:
        # Create a writer object from csv module
        csv_writer = writer(write_obj)
        # Add contents of list as last row in the csv file
        csv_writer.writerow(list_of_elem)

def remove():
    id = input("Enter ID : ")
    with open('students.csv', 'rb') as inp, open('students.csv', 'wb') as out:
        writer = csv.writer(out)
        for row in csv.reader(inp):
            if row[0] != id:
                writer.writerow(row)


# List of strings
row_contents = [11,'mayur','Java','Tokyo','Morning']
# Append a list as new line to an old csv file
add('students.csv', row_contents)
remove()

添加功能可以正常工作，但是当我尝试使用删除功能时，它会删除所有现有条目。任何人都可以帮助我。

Answer 1

首先，我将显示代码，然后在下面，我对更改进行一些评论。

from csv import writer
import csv

def add(file_name, list_of_elem):
    # Open file in append mode
    with open(file_name, 'a+', newline = '') as write_obj:
        # Create a writer object from csv module
        csv_writer = writer(write_obj)
        # Add contents of list as last row in the csv file
        csv_writer.writerow(list_of_elem)

def remove():
    idt = input("Enter ID : ")
    with open('students.csv', 'r') as inp:
        newrows = []
        data = csv.reader(inp)
        for row in data:
            if row[0] != idt:
                newrows.append(row)
    with open('students.csv', 'w') as out:
        csv_writer = writer(out)
        for row in newrows:
            csv_writer.writerow(row)

def display():
    with open('students.csv','r') as f:
        data = csv.reader(f)
        for row in data:
                print(row)

# List of strings
row_contents = [10,'mayur','Java','Tokyo','Morning']
add('students.csv', row_contents)
row_contents = [11,'mayur','Java','Tokyo','Morning']
add('students.csv', row_contents)
row_contents = [12,'mayur','Java','Tokyo','Morning']
add('students.csv', row_contents)
# Append a list as new line to an old csv file

display()
remove()

如果文件是CSV文件，则应使用text文件，而不是binary文件。
我将变量id的名称更改为ìdt，因为id是内置的，用于返回对象的标识，并且不是覆盖内置函数的好习惯。
要仅删除具有特定idt的行，应阅读所有文件，存储到var（列表）中，删除要删除的内容，然后保存结果。

Answer 2

您应该使用临时文件，而不要同时打开并写入同一文件。签出此答案：https://stackoverflow.com/a/17646958/14039323

如何使用python从csv文件中删除特定行

2 个答案: