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CREATE SCHEMA plv8;
CREATE FUNCTION valid_json(json text) RETURNS boolean
LANGUAGE plv8 IMMUTABLE STRICT
AS $$
try {
JSON.parse(json);
return true;
} catch(e) {
return false;
}
$$;
CREATE DOMAIN plv8.json AS text
CONSTRAINT json_check CHECK (valid_json(VALUE));
CREATE FUNCTION get_key(key text, json_raw text) RETURNS plv8.json
LANGUAGE plv8 IMMUTABLE STRICT
AS $$
var val = JSON.parse(json_raw)[key];
var ret = {};
ret[key] = val;
return JSON.stringify(ret);
$$;
CREATE TABLE jsononly (
data plv8.json
);
COPY jsononly (data) FROM stdin;
{"ok": true}
\.
-- Call twice to test the function cache.
SELECT get_key('ok', data) FROM jsononly;
SELECT get_key('ok', data) FROM jsononly;
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