如何在 Python 中追加 json 文件？

How to append in a json file in Python?

提问by PythonEnthusiast

I have the a json file whose contents is {"67790": {"1": {"kwh": 319.4}}}. Now I create a dictionary a_dictwhich I need to append it into the json file. I tried the following but was not able to do it correctly. Where I'm going wrong?

我有一个 json 文件，其内容是{"67790": {"1": {"kwh": 319.4}}}. 现在我创建了一个字典a_dict，我需要将它附加到 json 文件中。我尝试了以下操作，但无法正确执行。我哪里错了？

with open(DATA_FILENAME, 'a') as f:
   json_obj = json.dump(a_dict, json.load(f)
   f.write(json_obj)
   f.close()

采纳答案by alecxe

Assuming you have a test.jsonfile with the following content:

假设您有一个test.json包含以下内容的文件：

{"67790": {"1": {"kwh": 319.4}}}

Then, the code below will loadthe json file, update the data inside using dict.update()and dumpinto the test.jsonfile:

接着，下面的代码将loadJSON文件，里面更新使用数据dict.update()和dump到test.json文件：

import json

a_dict = {'new_key': 'new_value'}

with open('test.json') as f:
    data = json.load(f)

data.update(a_dict)

with open('test.json', 'w') as f:
    json.dump(data, f)

Then, in test.json, you'll have:

然后，在 中test.json，您将拥有：

{"new_key": "new_value", "67790": {"1": {"kwh": 319.4}}}

Hope this is what you wanted.

希望这是你想要的。

回答by Nicolas Barbey

You need to update the output of json.load with a_dict and then dump the result. And you cannot append to the file but you need to overwrite it.

您需要使用 a_dict 更新 json.load 的输出，然后转储结果。您不能附加到文件，但需要覆盖它。

回答by kodeslacker

json_obj=json.dumps(a_dict, ensure_ascii=False)