pub fn json_field_metadata() -> HashMap<String, String>Expand description
Field metadata used to mark a Utf8 field as containing raw JSON.
Attach this to any Arrow Field whose values are JSON-encoded strings so
downstream consumers can recognize them as JSON rather than opaque text.
Emits Arrow’s canonical JSON extension type keys
(ARROW:extension:name = arrow.json, ARROW:extension:metadata = {}),
see https://arrow.apache.org/docs/format/CanonicalExtensions.html#json.
Also emits a legacy is_json = true key. This key predates this crate’s
adoption of the canonical extension and is non-standard — no other Arrow
tool recognizes it. It is kept only for back-compat with existing
downstream consumers of this crate and will be removed in a future
release; new consumers should key off ARROW:extension:name instead.