python - 如何显示所有数据并将其保存在文本文件中？

Question

read = db.Student.find()
# use iter() to include loop for the first item index = 0
# use next(read, None) if you want to skip the first item index = 0
# object = iter(read)
object = iter(read)
'''Do a for loop to loop and print out each document'''
for object in read:
    with open("Student.txt", "w", newline="") as fp:
        read_records = str(object['_id']), str(object['ID']), object['item'], 
        str(object['qty'])
        r = ' '.join(read_records)
        print(r)
        fp.write(r)
        fp.close()

首先，我想从集合中检索所有数据。其次，我想将所有检索到的数据保存到文本文件中。但是，我只能设法保存最后一个元素的数据。我无法将文本文件中的第一个元素保存到第四个元素!请帮忙!

Answer 1

您将重新打开输出文件以在循环的每次迭代中进行写入。每次迭代都会以写入模式打开一个新文件，覆盖现有的“Students.txt”。

read = db.Student.find()
# use iter() to include loop for the first item index = 0
# use next(read, None) if you want to skip the first item index = 0
# object = iter(read)
object = iter(read)
'''Do a for loop to loop and print out each document'''
with open("Student.txt", "w", newline="") as fp:
  for object in read:
    read_records = str(object['_id']), str(object['ID']), object['item'], 
    str(object['qty'])
    r = ' '.join(read_records)
    print(r)
    fp.write(r)
  fp.close()

我相信这会解决您的问题。