Fix: ARRAY_AGG (and other arrays) may return [null]. (#413)

Author: isoos

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## 3.5.1
+
+- Fix: `ARRAY_AGG` (and other arrays) may return `[null]`.
+
 ## 3.5.0
 
 - Better exception stacktraces (in some cases) using `package:stack_trace`.

lib/src/types/binary_codec.dart

@@ -943,26 +943,36 @@ class PostgresBinaryDecoder {
     );
   }
 
-  static List<V> readListBytes<V>(Uint8List data,
-      V Function(ByteDataReader reader, int length) valueDecoder) {
+  static List<V?> readListBytes<V>(
+    Uint8List data,
+    V Function(ByteDataReader reader, int length) valueDecoder,
+  ) {
     if (data.length < 16) {
       return [];
     }
 
     final reader = ByteDataReader()..add(data);
     reader.read(12); // header
 
-    final decoded = [].cast<V>();
+    final decoded = <V?>[];
     final size = reader.readInt32();
 
     reader.read(4); // index
 
+    bool hasNull = false;
     for (var i = 0; i < size; i++) {
       final len = reader.readInt32();
-      decoded.add(valueDecoder(reader, len));
+      if (len == -1) {
+        decoded.add(null);
+        hasNull = true;
+      } else {
+        final v = valueDecoder(reader, len);
+        decoded.add(v);
+        hasNull = hasNull || (v == null);
+      }
     }
 
-    return decoded;
+    return hasNull ? decoded : decoded.cast<V>();
   }
 
   /// Decode numeric / decimal to String without loosing precision.

pubspec.yaml

@@ -1,6 +1,6 @@
 name: postgres
 description: PostgreSQL database driver. Supports statement reuse and binary protocol and connection pooling.
-version: 3.5.0
+version: 3.5.1
 homepage: https://github.com/isoos/postgresql-dart
 topics:
   - sql

test/not_enough_bytes_test.dart

@@ -0,0 +1,44 @@
+import 'package:postgres/postgres.dart';
+import 'package:test/test.dart';
+
+import 'docker.dart';
+
+void main() {
+  withPostgresServer('not enough bytes to read', (server) {
+    test('case #1', () async {
+      final conn = await server.newConnection();
+      await conn.execute(_testDdl, queryMode: QueryMode.simple);
+      final rs1 = await conn.execute('SELECT l.id, bn.novel_id as novels '
+          'FROM books l LEFT JOIN book_novel bn on l.id=bn.book_id;');
+      expect(rs1.single, [359, null]);
+
+      final rs2 =
+          await conn.execute('SELECT l.id, ARRAY_AGG(bn.novel_id) as novels '
+              'FROM books l LEFT JOIN book_novel bn on l.id=bn.book_id '
+              'GROUP BY l.id;');
+      expect(rs2.single, [
+        359,
+        [null]
+      ]);
+    });
+  });
+}
+
+final _testDdl = '''
+CREATE TABLE IF NOT EXISTS books (
+    id        			INTEGER   NOT NULL PRIMARY KEY,
+    title     			TEXT NOT NULL,
+    first_publication 	INTEGER,
+    notes      			TEXT,
+    opinion_id 			INTEGER NOT NULL
+);
+
+CREATE TABLE IF NOT EXISTS book_novel (
+    book_id    INTEGER NOT NULL,
+    novel_id INTEGER NOT NULL,
+    PRIMARY KEY (book_id,novel_id)
+);
+
+INSERT INTO books (id,title,first_publication,notes,opinion_id) VALUES (359,'The legacy of heorot',1987,NULL,0);
+INSERT INTO book_novel (book_id,novel_id) VALUES (1268,215);
+''';