jsonl.dumper¶

Low-level generator that yields formatted JSON Lines strings (or bytes) from an iterable of objects. This is the building block used internally by jsonl.dump and jsonl.dumps.

Function Signature¶

jsonl.dumper(iterable, *, text_mode=True, cls=None, **kwargs)

Parameters¶

Parameter	Type	Default	Description
`iterable`	`Iterable[Any]`	(required)	Iterable of JSON-serializable objects
`text_mode`	`bool`	`True`	If `True`, yield `str` lines; if `False`, yield `bytes`
`cls`	`type[json.JSONEncoder]` `Callable` or `None`	`json.JSONEncoder`	Custom encoder
`**kwargs`			Additional keyword arguments passed to the `cls` encoder

Returns¶

Iterator[str | bytes] — A generator yielding one formatted line per object (including trailing newline).

Examples¶

Basic usage¶

import jsonl

data = [{"name": "Alice"}, {"name": "Bob"}]

for line in jsonl.dumper(data):
    print(repr(line))

Output:

'{"name": "Alice"}\n'
'{"name": "Bob"}\n'

Yield bytes¶

import jsonl

data = [{"x": 1}, {"x": 2}]

for line in jsonl.dumper(data, text_mode=False):
    print(repr(line))

Output:

b'{"x": 1}\n'
b'{"x": 2}\n'

Stream to a custom destination¶

import jsonl

data = [{"event": "click"}, {"event": "scroll"}]

# Write lines to stdout or any writable target
import sys
for line in jsonl.dumper(data):
    sys.stdout.write(line)

With orjson¶

import orjson
import jsonl

data = [{"name": "Alice"}, {"name": "Bob"}]

for line in jsonl.dumper(data, text_mode=False, cls=orjson.dumps):
    print(repr(line))