feat(core): keep collection state of dirty collections after initiali…

…zing

Previously when collection was dirty and we load its contents, the dirty state
would be lost. Now we restore the dirty state after we load the items.

Closes #2408

packages/core/src/entity/Collection.ts

@@ -217,6 +217,18 @@ export class Collection<T, O = unknown> extends ArrayCollection<T, O> {
   }
 
   async init<P extends string = never>(options: InitOptions<T, P> = {}): Promise<this> {
+    if (this.dirty) {
+      const items = [...this.items];
+      this.dirty = false;
+      await this.init(options);
+
+      if (items.length) {
+        items.forEach(i => this.add(i));
+      }
+
+      return this;
+    }
+
     const em = this.getEntityManager();
 
     if (!this.initialized && this.property.reference === ReferenceType.MANY_TO_MANY && em.getPlatform().usesPivotTable()) {

tests/EntityManager.postgre.test.ts

@@ -7,7 +7,7 @@ import {
 } from '@mikro-orm/core';
 import { PostgreSqlDriver, PostgreSqlConnection } from '@mikro-orm/postgresql';
 import { Address2, Author2, Book2, BookTag2, FooBar2, FooBaz2, Publisher2, PublisherType, PublisherType2, Test2, Label2 } from './entities-sql';
-import { initORMPostgreSql, wipeDatabasePostgreSql } from './bootstrap';
+import { initORMPostgreSql, mockLogger, wipeDatabasePostgreSql } from './bootstrap';
 import { performance } from 'perf_hooks';
 
 describe('EntityManagerPostgre', () => {
@@ -1096,6 +1096,33 @@ describe('EntityManagerPostgre', () => {
     expect(wrap(tags[0].books.getItems()[0]).isInitialized()).toBe(true);
   });
 
+  test('populating dirty collections will merge the items and keep it dirty', async () => {
+    await createBooksWithTags();
+
+    const a = await orm.em.findOneOrFail(Author2, { email: 'snow@wall.st' });
+    expect(a.books.isDirty()).toBe(false);
+    a.books.add(new Book2('new book', a, 123));
+    expect(a.books.isDirty()).toBe(true);
+
+    const mock = mockLogger(orm, ['query']);
+    const books = await a.books.loadItems();
+    expect(a.books.isDirty()).toBe(true);
+    await orm.em.flush();
+    expect(a.books.isDirty()).toBe(false);
+    expect(books).toHaveLength(4);
+    expect(books.map(b => b.title)).toEqual([
+      'My Life on The Wall, part 1',
+      'My Life on The Wall, part 2',
+      'My Life on The Wall, part 3',
+      'new book',
+    ]);
+
+    expect(mock.mock.calls[0][0]).toMatch(`select "e0"."uuid_pk", "e0"."created_at", "e0"."title", "e0"."price", "e0"."double", "e0"."meta", "e0"."author_id", "e0"."publisher_id", "e0".price * 1.19 as "price_taxed" from "book2" as "e0" where "e0"."author_id" is not null and "e0"."author_id" = $1 order by "e0"."title" asc`);
+    expect(mock.mock.calls[1][0]).toMatch(`begin`);
+    expect(mock.mock.calls[2][0]).toMatch(`insert into "book2" ("author_id", "created_at", "price", "title", "uuid_pk") values ($1, $2, $3, $4, $5) returning "uuid_pk", "created_at", "title"`);
+    expect(mock.mock.calls[3][0]).toMatch(`commit`);
+  });
+
   test('nested populating', async () => {
     const author = new Author2('Jon Snow', 'snow@wall.st');
     const book1 = new Book2('My Life on The Wall, part 1', author);