CGI: Use PostgreSQL 17's json_serialize() function.

To avoid JSON-encoding on the Python side.

1 files changed, 3 insertions, 6 deletions

diff --git a/webmap-cgi b/webmap-cgi
index b5e5f98..3196943 100755
--- a/webmap-cgi
+++ b/webmap-cgi
@@ -23,7 +23,7 @@
 
 import sys
 from os import path as os_path
-from json import load as json_load, dumps as json_dumps, JSONDecodeError
+from json import load as json_load, JSONDecodeError
 import logging
 from typing import Final, Iterator
 import atexit
@@ -163,10 +163,7 @@ def get_query_map(layernames : set[str]) -> dict[str,bytes]:
             query +=                common.escape_identifier(layername) + ' m '
             query +=      'WHERE m.' + common.escape_identifier(pkey_col) + ' = %s'
             query += ') '
-            # TODO[trixie] use json_serialize() from PostgreSQL 17 to avoid serializing on
-            # the Python side.  (There is also row_to_json() which might be of interest if
-            # json not jsonb is needed.)
-            query += 'SELECT to_jsonb(feature) FROM feature'
+            query += 'SELECT json_serialize(to_json(feature) RETURNING bytea) FROM feature'
             # The query never returns more than one row since we filter on a single FID.
             # TODO: batch queries using ANY[] or an IN set (the # consummer will then need
             # to re-order the response)
@@ -237,7 +234,7 @@ def application(env, start_response) -> Iterator[bytes]:
                     first = False
                 else:
                     yield b','
-                yield json_dumps(resp[0], ensure_ascii=False, separators=(',', ':')).encode('utf-8')
+                yield resp[0]
                 # the query never returns more than one row since we filter on a single FID
         if first:
             yield b'[]' # no match, empty response