fix(mongo): support cursor pagination on Date properties

Closes #5496

packages/core/src/utils/Cursor.ts

@@ -163,7 +163,13 @@ export class Cursor<
   }
 
   static decode(value: string): unknown[] {
-    return JSON.parse(Buffer.from(value, 'base64url').toString('utf8'));
+    return JSON.parse(Buffer.from(value, 'base64url').toString('utf8')).map((value: unknown) => {
+      if (typeof value === 'string' && value.match(/^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}\.\d{3}/)) {
+        return new Date(value);
+      }
+
+      return value;
+    });
   }
 
   static getDefinition<Entity extends object>(meta: EntityMetadata<Entity>, orderBy: OrderDefinition<Entity>) {

tests/features/cursor-based-pagination/GH5478.test.ts

@@ -0,0 +1,63 @@
+import { ObjectId, MikroORM, Entity, PrimaryKey, Property } from '@mikro-orm/mongodb';
+
+@Entity()
+class EntityForFindByCursorTest {
+
+  @PrimaryKey()
+  _id!: ObjectId;
+
+  @Property()
+  myDate: Date;
+
+  @Property()
+  bar?: string;
+
+  constructor(myDate: Date) {
+    this.myDate = myDate;
+    this.bar = 'bar';
+  }
+
+}
+
+let orm: MikroORM;
+
+beforeAll(async () => {
+  orm = MikroORM.initSync({
+    entities: [EntityForFindByCursorTest],
+    dbName: 'mikro-orm-test',
+  });
+  await orm.em.nativeDelete(EntityForFindByCursorTest, {});
+});
+
+afterAll(() => orm.close(true));
+
+test('empty result with findByCursor and orderBy with Date', async () => {
+  orm.em.create(EntityForFindByCursorTest, { myDate: new Date('2020-01-01T00:00:00.000Z') });
+  orm.em.create(EntityForFindByCursorTest, { myDate: new Date('2020-01-02T00:00:00.000Z') });
+  orm.em.create(EntityForFindByCursorTest, { myDate: new Date('2020-01-03T00:00:00.000Z') });
+  orm.em.create(EntityForFindByCursorTest, { myDate: new Date('2020-01-04T00:00:00.000Z') });
+  orm.em.create(EntityForFindByCursorTest, { myDate: new Date('2020-01-05T00:00:00.000Z') });
+  await orm.em.flush();
+  orm.em.clear();
+
+  const all = await orm.em.findAll(EntityForFindByCursorTest);
+  expect(all.length).toBe(5);
+
+  const curOne = await orm.em.findByCursor(EntityForFindByCursorTest, {}, {
+    first: 3,
+    orderBy: { myDate: 'ASC' },
+  });
+
+  expect(curOne.length).toBe(3);
+
+  orm.em.clear();
+
+  const curTwo = await orm.em.findByCursor(EntityForFindByCursorTest, {}, {
+    first: 3,
+    after: curOne,
+    orderBy: { myDate: 'ASC' },
+  });
+
+  expect(curTwo.length).toBe(2);
+
+});