fix(core): ensure M:N collections are not dirty after populating of i…

…nverse side

Closes #3287

packages/core/src/entity/Collection.ts

@@ -135,10 +135,10 @@ export class Collection<T, O = unknown> extends ArrayCollection<T, O> {
   /**
    * @internal
    */
-  hydrate(items: T[]): void {
+  hydrate(items: T[], forcePropagate?: boolean): void {
     this.initialized = true;
     super.hydrate(items);
-    this.takeSnapshot();
+    this.takeSnapshot(forcePropagate);
   }
 
   /**
@@ -251,11 +251,11 @@ export class Collection<T, O = unknown> extends ArrayCollection<T, O> {
   /**
    * @internal
    */
-  takeSnapshot(): void {
+  takeSnapshot(forcePropagate?: boolean): void {
     this.snapshot = [...this.items];
     this.setDirty(false);
 
-    if (this.property.owner) {
+    if (this.property.owner || forcePropagate) {
       this.items.forEach(item => {
         this.propagate(item, 'takeSnapshot');
       });

packages/core/src/entity/EntityLoader.ts

@@ -225,7 +225,7 @@ export class EntityLoader {
   private initializeManyToMany<T extends AnyEntity<T>>(filtered: T[], children: AnyEntity[], prop: EntityProperty, field: keyof T): void {
     for (const entity of filtered) {
       const items = children.filter(child => (child[prop.mappedBy] as unknown as Collection<AnyEntity>).contains(entity));
-      (entity[field] as unknown as Collection<AnyEntity>).hydrate(items);
+      (entity[field] as unknown as Collection<AnyEntity>).hydrate(items, true);
     }
   }
 
@@ -349,7 +349,7 @@ export class EntityLoader {
         });
         return this.em.getUnitOfWork().registerManaged<T>(entity, item, { refresh, loaded: true });
       });
-      (entity[prop.name] as unknown as Collection<AnyEntity>).hydrate(items);
+      (entity[prop.name] as unknown as Collection<AnyEntity>).hydrate(items, true);
       children.push(...items);
     }
 

packages/mariadb/src/MariaDbSchemaHelper.ts

@@ -232,8 +232,7 @@ export class MariaDbSchemaHelper extends SchemaHelper {
   }
 
   protected wrap(val: string | undefined | null, type: Type<unknown>): string | undefined | null {
-    const stringType = type instanceof StringType || type instanceof TextType || type instanceof EnumType;
-    return typeof val === 'string' && val.length > 0 && stringType ? this.platform.quoteValue(val) : val;
+    return val;
   }
 
 }

tests/issues/GH3287.test.ts

@@ -0,0 +1,56 @@
+import { Collection, Entity, ManyToMany, MikroORM, PrimaryKey } from '@mikro-orm/core';
+
+@Entity()
+export class Group {
+
+  @PrimaryKey()
+  id!: number;
+
+  @ManyToMany({
+    entity: 'Participant',
+    mappedBy: 'groups',
+  })
+  participants = new Collection<Participant>(this);
+
+}
+
+@Entity()
+export class Participant {
+
+  @PrimaryKey()
+  id!: number;
+
+  @ManyToMany({
+    entity: () => Group,
+    inversedBy: 'participants',
+  })
+  groups = new Collection<Group>(this);
+
+}
+
+let orm: MikroORM;
+
+beforeAll(async () => {
+  orm = await MikroORM.init({
+    entities: [Participant],
+    dbName: ':memory:',
+    type: 'better-sqlite',
+  });
+  await orm.getSchemaGenerator().createSchema();
+});
+
+afterAll(() => orm.close(true));
+
+test('removing items from m:n (GH 3287)', async () => {
+  const group1 = new Group();
+  group1.participants.add(new Participant());
+  await orm.em.fork().persistAndFlush(group1);
+
+  const group = await orm.em.findOneOrFail(Group, group1, {
+    populate: ['participants'],
+  });
+
+  orm.em.remove(group);
+
+  await orm.em.flush();
+});