jsonseq

jsonseq

RFC 7464 JSON Text Sequences encoding and decoding for Python.

Usage

The jsonseq.encode.JSONSeqEncoder class takes streams of JSON-serializable Python objects and yields for each object its JSON representation sandwiched between an optional ASCII record separator (RS, \x1e) and a newline (\n).

>>> from jsonseq.encode import JSONSeqEncoder
>>> for chunk in JSONSeqEncoder().encode(({"a": i, "b": i} for i in range(3))):
...     print(repr(chunk))
...
'{"a": 0, "b": 0}\n'
'{"a": 1, "b": 1}\n'
'{"a": 2, "b": 2}\n'

The RS allows pretty-printed JSON to be streamed out in sequences that can be decoded again.

>>> for chunk in JSONSeqEncoder(with_rs=True, indent=2).encode(({"a": i, "b": i} for i in range(3))):
...     print(repr(chunk))
...
'\x1e{\n  "a": 0,\n  "b": 0\n}\n'
'\x1e{\n  "a": 1,\n  "b": 1\n}\n'
'\x1e{\n  "a": 2,\n  "b": 2\n}\n'

You can also get small chunks of the JSON sequences as they are encoded with the iterencode() method.

>>> for chunk in JSONSeqEncoder(with_rs=True).iterencode(({"a": i} for i in range(3))):
...     print(repr(chunk))
...
'\x1e'
'{'
'"a"'
': '
'0'
'}'
'\n'
'\x1e'
'{'
'"a"'
': '
'1'
'}'
'\n'
'\x1e'
'{'
'"a"'
': '
'2'
'}'
'\n'

You can use either encode() or iterencode() to copy JSON text sequences to a file.

with open("/tmp/example.jsons", "w") as f:
    for chunk in JSONSeqEncoder(with_rs=True, indent=2).iterencode(({"a": i, "b": i} for i in range(3))):
        f.write(chunk)

There is no need to add a newline when calling the file's write() method. JSONSeqEncoder ensures that it's already there where it needs to be.

The jsonseq.decode.JSONSeqDecoder class takes streams of JSON texts sandwiched between the optional ASCII record separator (RS, \x1e) and a newline (\n) and yields decoded Python objects.

>>> stream = ['\x1e', '{', '"a"', ': ', '0', '}', '\n', '\x1e', '{', '"a"', ': ', '1', '}', '\n', '\x1e', '{', '"a"', ': ', '2', '}', '\n']
>>> for obj in JSONSeqDecoder().decode(stream):
...     print(repr(obj))
...
{'a': 0}
{'a': 1}
{'a': 2}

Objects can be read from a file in the same way.

>>> with open("/tmp/example.jsons") as f:
...     for obj in JSONSeqDecoder().decode(f):
...         print(repr(obj))
...
{'a': 0, 'b': 0}
{'a': 1, 'b': 1}
{'a': 2, 'b': 2}