将值添加到现有的json文件中，而无需重写它 [英] Add values to existing json file without rewriting it

问题描述

我在JSON文件中的字典如下:

My dictionary in a JSON file looks like this:

{
'key1':value1
'key2':value2
}

我正在编写一个循环，其中每次迭代都会向文件中的字典添加新键.例如，经过一轮迭代后，文件中的字典如下所示:

I'm writing a loop where each iteration adds a new key to the dictionary in the file. For example, after one iteration the dictionary in the file looks like this:

{
'key1':value1
'key2':value2
'key3':value3
}

我想使用一种方法将新密钥直接附加到文件中的字典中.我不想读文件，更改数据并再次写回.有什么办法吗?

I want to use a method to directly append a new key into the dictionary in the file. I don't want to have to read the file in, change data and write it back out again. Is there any way to do this?

推荐答案

这是一个非常粗略的实现，它假定文件以}和换行符结尾(解释-2):

This is a rather crude implementation that assumes that the file ends with } and a newline (which explains the -2):

with open('data.json','rb+') as f:
    f.seek(-2,2)
    f.write(b"'new_key':new_value\n}\n")

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