update_table_json.sql

CREATE OR REPLACE FUNCTION generate_update_query(value JSON, tbl TEXT) RETURNS TEXT as $$
DECLARE
    key TEXT;
    sets TEXT[];
BEGIN
    FOR key IN
        SELECT json_object_keys(value)
    LOOP
        IF (key != 'id') THEN
            SELECT array_append(sets, format('%I=%L', key, value->>key)) INTO sets;
        END IF;
    END LOOP;
    RETURN format('UPDATE %I SET ', tbl) || array_to_string(sets, ', ') || format(' WHERE id=%L', (value->>'id')::integer);
END;
$$ language 'plpgsql';