Reading and writing JSON, YAML, TOML, XML

The other four codecs — and what happens when a value doesn't fit.

Doc.from_* reads a format into a Document; Doc.to_* writes one back out. JSON, YAML, TOML, and XML all read into the exact same Document that OML does — converting between any of the five is just read one, write another:

from omnist import Doc

Doc.from_json('{"name": "Ann", "tags": ["x", "y"]}').to_toml()
Doc.from_yaml("name: Ann\n").to_json()

Output

to_toml():
name = "Ann"
tags = [
    "x",
    "y",
]

to_json(): {"name": "Ann"}

Writing is lenient by default — a value a format can't hold the way it was typed (JSON/XML have no native date type) gets adjusted, and the adjustment is recorded, not silently lost:

from omnist import doc, WriteReport, WriteError
import datetime

d = doc({"d": datetime.date(2024, 1, 1)})
d.to_json()                          # stringified, still succeeds

rep = WriteReport()
d.to_json(report=rep)                # inspect what changed
[(a.code, a.severity) for a in rep]

d.to_json(strict=True)               # raises instead of adjusting

Output

to_json(): {"d": "2024-01-01"}
report: [('temporal.stringified', 'warning')]
strict raised WriteError: warning: $.d: temporal value written as an ISO-8601 string

A value with no legal representation at all (TOML has no null, and there's no safe substitute) fails unconditionally instead of guessing — check_json/check_yaml/check_toml/check_xml (and the matching Doc methods) simulate a write and return the report without producing output, so you can ask "would this be lossy?" without writing anything:

d.check_json()

Output

warning: $.d: temporal value written as an ISO-8601 string

Reading and writing JSON, YAML, TOML, XML

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