Merge pull request #1567 from Husssam12/develop

Add random ordering

drift/CHANGELOG.md

@@ -8,6 +8,7 @@
 - Allow the generator to emit correct SQL code when using arrays with the
   `new_sql_code_generation` option in specific scenarios.
 - Add the `generatedAs` method to declare generated columns for Dart tables.
+- Add `OrderingTerm.random` to fetch rows in a random order.
 - Improved support for pausing query stream subscriptions. Instead of buffering events,
   query streams will suspend fetching data if all listeners are paused.
 

drift/lib/src/runtime/query_builder/components/order_by.dart

@@ -37,6 +37,12 @@ class OrderingTerm extends Component {
     return OrderingTerm(expression: expression, mode: OrderingMode.desc);
   }
 
+  /// Creates an ordering term  to get a number of random rows
+  /// using sqlite random function.
+  factory OrderingTerm.random() {
+    return OrderingTerm(expression: FunctionCallExpression('random', []));
+  }
+
   @override
   void writeInto(GenerationContext context) {
     expression.writeInto(context);

drift/test/integration_tests/insert_integration_test.dart

@@ -13,6 +13,8 @@ void main() {
     db = TodoDb(NativeDatabase.memory());
   });
 
+  tearDown(() => db.close());
+
   test('insertOnConflictUpdate', () async {
     await db.into(db.categories).insert(
         CategoriesCompanion.insert(description: 'original description'));

drift/test/integration_tests/select_integration_test.dart

@@ -0,0 +1,32 @@
+@TestOn('vm')
+import 'package:collection/collection.dart';
+import 'package:drift/drift.dart';
+import 'package:drift/native.dart';
+import 'package:test/test.dart';
+
+import '../data/tables/todos.dart';
+
+void main() {
+  late TodoDb db;
+
+  setUp(() {
+    db = TodoDb(NativeDatabase.memory());
+  });
+
+  tearDown(() => db.close());
+
+  test('can use random ordering', () async {
+    await db.batch((b) {
+      b.insertAll(db.users, [
+        for (var i = 0; i < 1000; i++)
+          UsersCompanion.insert(
+              name: 'user name', profilePicture: Uint8List(0)),
+      ]);
+    });
+
+    final rows = await (db.select(db.users)
+          ..orderBy([(_) => OrderingTerm.random()]))
+        .get();
+    expect(rows.isSorted((a, b) => a.id.compareTo(b.id)), isFalse);
+  });
+}

drift/test/select_test.dart

@@ -70,6 +70,14 @@ void main() {
           argThat(isEmpty)));
     });
 
+    test('with random order by clause', () async {
+      await (db.select(db.users)..orderBy([(u) => OrderingTerm.random()]))
+          .get();
+
+      verify(executor.runSelect(
+          'SELECT * FROM users ORDER BY random() ASC;', argThat(isEmpty)));
+    });
+
     test('with complex predicates', () async {
       await (db.select(db.users)
             ..where((u) =>