How to Extract Multiple JSON Objects from a Single File: A Pythonic Solution

Extracting Multiple JSON Objects from a Single File

When encountering a JSON file containing numerous JSON objects, it's essential to have a comprehensive approach to extracting specific data. This article delves into a solution for extracting "Timestamp" and "Usefulness" values from such a file.

The provided JSON file structure exhibits stacked JSON objects. To parse and retrieve the desired data, consider using the json.JSONDecoder.raw_decode function. This function allows for the decoding of arbitrarily large JSON strings while adhering to memory constraints.

However, it's important to note that the Python json module doesn't accept strings with prefixing whitespace. Thus, a regular expression is employed to search for the first non-whitespace character, which serves as the starting point for parsing.

Below is a revised solution that addresses this issue:

<code class="python">from json import JSONDecoder, JSONDecodeError
import re

NOT_WHITESPACE = re.compile(r'\S')

def decode_stacked(document, pos=0, decoder=JSONDecoder()):
    while True:
        match = NOT_WHITESPACE.search(document, pos)
        if not match:
            return
        pos = match.start()
        
        try:
            obj, pos = decoder.raw_decode(document, pos)
        except JSONDecodeError:
            # do something sensible if there's some error
            raise
        yield obj</code>

The revised code snippet effectively parses the stacked JSON objects within the given document, returning each object as it encounters it. This approach avoids the limitations of traditional JSON parsing, making it suitable for handling large and potentially complex JSON files.

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