Clean up rows_as_map transaction fix per PR lpil#74 review

Address the inline review feedback on the cherry-picked fix:

- Replace `element(11, Conn)` with `Conn#conn.decode_opts` by
  including pgo_internal.hrl. The header is private (it lives in
  pgo/src/, not pgo/include/), so the include is annotated to
  flag the dependency on internal PGO shape.
- Split the in-transaction assertion out of expected_maps_test
  into a dedicated transaction_respects_rows_as_map_test, with a
  comment explaining the regression it covers.
- Add an Unreleased CHANGELOG entry for the bug fix.

Verified the new test fails (UnexpectedResultType, Dict vs Array)
when pog_ffi:query/4 reverts to the pre-fix call, and all 32
tests pass with the fix.

Author: mbuhot

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## Unreleased
+
+- Fixed a bug where queries inside `pog.transaction` did not respect the pool's
+  `rows_as_map` configuration. Rows are now returned as maps when the pool is
+  configured with `rows_as_map: True`, both inside and outside transactions.
+
 ## v4.1.0 - 2025-07-14
 
 - Added a `numeric_decoder` to decode numeric types coming from postgres.

src/pog_ffi.erl

@@ -4,6 +4,10 @@
 
 -include_lib("pog/include/pog_Config.hrl").
 -include_lib("pg_types/include/pg_types.hrl").
+%% pgo_internal.hrl is a private header (it lives in pgo/src/, not pgo/include/).
+%% We rely on it to read decode_opts off the #conn{} record because
+%% pgo_handler:extended_query/4 ignores Conn#conn.decode_opts and hardcodes [].
+-include_lib("pgo/src/pgo_internal.hrl").
 
 null() ->
     null.
@@ -85,8 +89,7 @@ start(Config) ->
 query(Pool, Sql, Arguments, Timeout) ->
     Res = case Pool of
         {single_connection, Conn} ->
-              DecodeOpts = element(11, Conn),
-              pgo_handler:extended_query(Conn, Sql, Arguments, DecodeOpts, #{});
+            pgo_handler:extended_query(Conn, Sql, Arguments, Conn#conn.decode_opts, #{});
         {pool, Name} ->
             Options = #{
                 pool => Name,

test/pog_test.gleam

@@ -515,25 +515,13 @@ pub fn expected_maps_test() {
     VALUES
       (DEFAULT, 'neo', true, ARRAY ['black'], '2022-10-10 11:30:30', '2020-03-04')
     RETURNING
-      id, name"
+      id"
 
   let assert Ok(pog.Returned(rows: [id], ..)) =
     pog.query(sql)
     |> pog.returning(decode.at(["id"], decode.int))
     |> pog.execute(db.data)
 
-  let assert Ok(pog.Returned(1, ["neo"])) =
-    pog.transaction(db.data, fn(conn) {
-      let assert Ok(returned) =
-        pog.query(sql)
-        |> pog.returning(decode.at(["name"], decode.string))
-        |> pog.execute(conn)
-
-      assert returned.rows == ["neo"]
-
-      Ok(returned)
-    })
-
   let assert Ok(returned) =
     pog.query("SELECT * FROM cats WHERE id = $1")
     |> pog.parameter(pog.int(id))
@@ -571,6 +559,41 @@ pub fn expected_maps_test() {
   disconnect(db)
 }
 
+// Regression test: queries run inside `pog.transaction` against the checked-out
+// single connection must honour the pool's `rows_as_map` setting. Prior to the
+// fix in pog_ffi:query/4, decode_opts were not threaded through and rows came
+// back as positional tuples even when the pool was configured with
+// `rows_as_map: True`.
+pub fn transaction_respects_rows_as_map_test() {
+  let name = process.new_name("pog_test")
+  let assert Ok(db) =
+    pog.Config(..default_config(name), rows_as_map: True)
+    |> pog.start
+
+  let sql =
+    "
+    INSERT INTO
+      cats
+    VALUES
+      (DEFAULT, 'neo', true, ARRAY ['black'], '2022-10-10 11:30:30', '2020-03-04')
+    RETURNING
+      id, name"
+
+  let assert Ok(pog.Returned(1, ["neo"])) =
+    pog.transaction(db.data, fn(conn) {
+      let assert Ok(returned) =
+        pog.query(sql)
+        |> pog.returning(decode.at(["name"], decode.string))
+        |> pog.execute(conn)
+
+      assert returned.rows == ["neo"]
+
+      Ok(returned)
+    })
+
+  disconnect(db)
+}
+
 pub fn transaction_commit_test() {
   let db = start_default()
   let id_decoder = decode.at([0], decode.int)