fix(core): support calling em.findAndCount() on virtual entities wi…

…th `orderBy`

Closes #4628

packages/core/src/EntityManager.ts

@@ -1196,11 +1196,13 @@ export class EntityManager<D extends IDatabaseDriver = IDatabaseDriver> {
     Entity extends object,
     Hint extends string = never,
   >(entityName: EntityName<Entity>, where: FilterQuery<Entity> = {} as FilterQuery<Entity>, options: CountOptions<Entity, Hint> = {}): Promise<number> {
+    options = { ...options };
     const em = this.getContext(false);
     entityName = Utils.className(entityName);
     where = await em.processWhere(entityName, where, options as FindOptions<Entity, Hint>, 'read') as FilterQuery<Entity>;
     options.populate = em.preparePopulate(entityName, options) as unknown as Populate<Entity>;
     em.validator.validateParams(where);
+    delete (options as FindOptions<Entity>).orderBy;
 
     const cached = await em.tryCache<Entity, number>(entityName, options.cache, [entityName, 'em.count', options, where]);
 

tests/features/virtual-entities/GH4628.test.ts

@@ -0,0 +1,44 @@
+import { Entity, PrimaryKey, Property, SimpleLogger } from '@mikro-orm/core';
+import { MikroORM } from '@mikro-orm/postgresql';
+import { mockLogger } from '../../bootstrap';
+
+@Entity()
+class Book {
+
+  @PrimaryKey()
+  id!: number;
+
+  @Property()
+  title!: string;
+
+}
+
+@Entity({ expression: 'select title from book' })
+class BookSimple {
+
+  @Property()
+  title!: string;
+
+}
+
+let orm: MikroORM;
+
+beforeAll(async () => {
+  orm = await MikroORM.init({
+    dbName: 'virtual_entities',
+    entities: [Book, BookSimple],
+    loggerFactory: options => new SimpleLogger(options),
+  });
+  await orm.schema.refreshDatabase();
+});
+beforeEach(async () => orm.schema.clearDatabase());
+afterAll(async () => orm.close(true));
+
+test('virtual entities (postgres)', async () => {
+  const mock = mockLogger(orm);
+  await orm.em.findAndCount(BookSimple, {}, { orderBy: { title: 1 } });
+  expect(mock.mock.calls.map(r => r[0]).sort()).toEqual([
+    `[query] select * from (select title from book) as "b0" order by "b0"."title" asc`,
+    `[query] select count(*) as count from (select title from book) as "b0"`,
+  ]);
+});