Json.dump failing with 'must be unicode, not str' TypeError

Question

I have a json file which happens to have a multitude of Chinese and Japanese (and other language) characters. I\'m loading it into my python 2.7 script using io.open

Answer 1

The JSON module handles encoding and decoding for you, so you can simply open the input and output files in binary mode. The JSON module assumes UTF-8 encoding, but can be changed using encoding attribute on the load() and dump() methods.

with open('multiIdName.json', 'rb') as json_data:
    cards = json.load(json_data)

then:

with open("testJson.json", 'wb') as outfile:
    json.dump(cards, outfile, ensure_ascii=False)

Thanks to @Antti Haapala, Python 2.x JSON module gives either Unicode or str depending on the contents of the object.

You will have to add a sense check to ensure the result is a Unicode before writing through io:

with io.open("testJson.json", 'w', encoding="utf-8") as outfile:
    my_json_str = json.dumps(my_obj, ensure_ascii=False)
    if isinstance(my_json_str, str):
        my_json_str = my_json_str.decode("utf-8")

    outfile.write(my_json_str)