How to Extract Multiple JSON Objects from a Single File in Python?

Extracting Multiple JSON Objects from a Single File

In situations where you encounter a JSON file containing multiple objects, the task of isolating specific fields becomes essential. One approach involves utilizing the json.JSONDecoder.raw_decode method.

raw_decode offers the ability to iteratively decode large JSON strings. It continues parsing until a valid JSON object is encountered, while tracking the last non-whitespace position. This allows for repeated calls to raw_decode by providing the previous end position as an argument.

However, Python's JSON module requires whitespace-free input. Therefore, preprocessing is necessary to remove preceding whitespace. The provided code addresses this by utilizing the NOT_WHITESPACE regular expression to locate the initial non-empty character.

<code class="python"># Extract Multiple JSON Objects
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:
            # Handle error accordingly
            raise

        yield obj

# Example usage
s = """
{&quot;a&quot;: 1}
   [
1
,
2
]
"""

for obj in decode_stacked(s):
    print(obj)</code>

The output demonstrates the successful extraction of the multiple JSON objects from the input string:

{'a': 1}
[1, 2]

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