Python3.3 error loadng a JSON file with multiple entries

Question

I have a JSON file named debug.json that I created in Python3.3 that looks like this:

{"TIME": 55.55, "ID":155,"DATA": [17,22,33,44,55]}{"TIME": 56.55, "ID":195,"DATA": [17,22,ff,44,55]}

I'm trying to load it with the following code:

import json
with open("debug.json",'r',encoding='utf-8') as f:
    testing = json.loads(f.read())

However when I try this I get the following error:

ValueError: Extra data line 1 column 92

This is where the second JSON object starts in the text file...I'm guessing that I am missing something pretty trivial here but I haven't found any examples that relate to my problem. Any help is appreciated!

I know this question is quite old, but FYI for anyone else who stumbles across it: The real issue here is that a JSON document - which is what python's json parser knows how to read - is composed of exactly one JSON value, which can be an object, array, string, number, boolean, or null. The contents of "debug.json" is not a valid JSON document; it's multiple JSON objects in a row. That's why it needs to be read piecemeal with raw_decode(). — Chris Hillery
– Chris Hillery, Commented May 31, 2022 at 2:42

score 2 · Accepted Answer · 2014-06-19 01:13:15Z

Use json.JSONDecoder.raw_decode, which accepts JSON with extra data at the end, such as another JSON object, and returns a tuple with the first object decoded and the position of the next object.

Example with your JSON :

import json

js = """{"TIME": 55.55, "ID":155,"DATA": [17,22,33,44,55]}{"TIME": 56.55, "ID":195,"DATA": [17,22,ff,44,55]}"""

json.JSONDecoder().raw_decode(js) # ({'TIME': 55.55, 'DATA': [17, 22, 33, 44, 55], 'ID': 155}, 50)

js[50:] # '{"TIME": 56.55, "ID":195,"DATA": [17,22,ff,44,55]}'

As you can see, it successfully decoded the first object and told us where the next object starts (in this case at the 50th character).

Here is a function that I made that can decode multiple JSON objects and returns a list with all of them :

def multipleJSONDecode(js):
    result = []
    while js:
        obj, pos = json.JSONDecoder().raw_decode(js)
        result.append(obj)
        js = js[pos:]
    return result

Arkady · Accepted Answer · 2014-06-19 01:00:51Z

0

When you create the file, make sure that you have at most one valid JSON string per line. Then, when you need to read them back out, you can loop over the lines in the file one at a time:

import json
testing = []
with open("debug.json",'r',encoding='utf-8') as f:
    for line in f:
        testing.append(json.loads(line))

answered Jun 19, 2014 at 1:00

Arkady

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