jsonl.loader¶

Low-level generator that deserializes a line stream into Python objects. This is the building block used internally by jsonl.load.

Function Signature¶

jsonl.loader(stream, broken, *, cls=None, **kwargs)

Parameters¶

Parameter	Type	Default	Description
`stream`	iterable of `str` or `bytes`	(required)	Any iterable yielding one JSON line per iteration
`broken`	`bool`	(required)	If `True`, skip malformed lines and log a warning
`cls`	`type[json.JSONDecoder]` or `Callable` or `None`	`json.JSONDecoder`	Custom decoder
`**kwargs`			Keyword arguments passed to the Custom decoder (`cls`)

Returns¶

Iterator[Any] — An iterator yielding deserialized Python objects, one per line.

Examples¶

Deserialize from an in-memory list¶

import jsonl

lines = ['{"name": "Alice"}\n', '{"name": "Bob"}\n']

for item in jsonl.loader(lines, False):
    print(item)

Output:

{'name': 'Alice'}
{'name': 'Bob'}

Deserialize bytes lines¶

import jsonl

lines = [b'{"x": 1}\n', b'{"x": 2}\n']

for item in jsonl.loader(lines, False):
    print(item)

Skip malformed lines¶

import jsonl

lines = ['{"valid": true}\n', 'not json\n', '{"also": "valid"}\n']

for item in jsonl.loader(lines, True):
    print(item)

Output:

{'valid': True}
{'also': 'valid'}

With a custom decoder¶

import orjson
import jsonl

lines = [b'{"name": "Alice"}\n', b'{"name": "Bob"}\n']

for item in jsonl.loader(lines, False, cls=orjson.loads):
    print(item)