fix(core): do not infer populate: ['*'] from fields: ['*']

Closes #5139

packages/core/src/EntityManager.ts

@@ -2028,11 +2028,11 @@ export class EntityManager<D extends IDatabaseDriver = IDatabaseDriver> {
       // we need to prune the `populate` hint from to-one relations, as partially loading them does not require their population, we want just the FK
       const pruneToOneRelations = (meta: EntityMetadata, fields: string[]): string[] => {
         return fields.filter(field => {
-          if (!field.includes('.')) {
-            if (field === '*') {
-              return true;
-            }
+          if (field === '*') {
+            return false;
+          }
 
+          if (!field.includes('.')) {
             return ![ReferenceKind.MANY_TO_ONE, ReferenceKind.ONE_TO_ONE].includes(meta.properties[field].kind);
           }
 
@@ -2041,7 +2041,7 @@ export class EntityManager<D extends IDatabaseDriver = IDatabaseDriver> {
 
           /* istanbul ignore next */
           if (key === '*') {
-            return true;
+            return false;
           }
 
           const prop = meta.properties[key];

tests/features/partial-loading/GH5139.test.ts

@@ -0,0 +1,55 @@
+import {
+  Entity,
+  Ref,
+  ManyToOne,
+  MikroORM,
+  PrimaryKey, OneToMany, Collection,
+} from '@mikro-orm/sqlite';
+
+@Entity()
+class City  {
+
+  @PrimaryKey()
+  id!: number;
+
+  @OneToMany(() => School, s => s.city)
+  schools = new Collection<School>(this);
+
+}
+
+@Entity()
+class School {
+
+  @PrimaryKey()
+  id!: number;
+
+  @ManyToOne(() => City, { ref: true })
+  city!: Ref<City>;
+
+}
+
+
+let orm: MikroORM;
+
+beforeAll(async () => {
+  orm = await MikroORM.init({
+    dbName: ':memory:',
+    entities: [City],
+  });
+  await orm.schema.createSchema();
+
+  await orm.em.insert(City, { id: 1 });
+  await orm.em.insertMany(School, [
+    { id: 1, city: 1 },
+    { id: 2, city: 1 },
+  ]);
+});
+
+afterAll(async () => {
+  await orm.close(true);
+});
+
+test(`GH issue 5139`, async () => {
+  const city = await orm.em.find(City, { id: 1 }, { fields: ['*'] });
+  expect(city[0].schools.isInitialized()).toBe(false);
+});