Xqlite.TypeExtension.JSON (Xqlite v0.8.0)

Type extension for plain maps and lists ↔ JSON text.

Encodes plain (non-struct) maps and lists to JSON text via Jason.encode/1. Decodes TEXT that looks like a JSON object or array back to Elixir terms via Jason.decode/1.

Structs are deliberately not encoded — a Date, NaiveDateTime, Decimal, etc. belongs to its own extension, and capturing it here would shadow the more specific converter. Terms Jason cannot encode (for example a map holding an invalid-UTF-8 binary value) return :skip, so they fall through to the NIF's own structured rejection instead of being swallowed.

Round-trip caveat

Decoding is shape-driven: any stored TEXT whose first non-whitespace byte is { or [ and which parses as JSON will be decoded to a map or list. That is the point of opting in — but it means a column that merely happens to hold JSON-shaped text is also decoded. Place more specific extensions before this one in the chain (they win on decode/1 via first-match), and only enable JSON for queries whose JSON-shaped columns you actually want parsed.

Object keys round-trip as strings (JSON has no atom keys): encoding %{a: 1} and decoding yields %{"a" => 1}.