fix(core): allow populating FK as PK in toJSON()

Previously when entity was used as PK, it was always serialized to that entity PK.
With this fix, it will respect the populate parameter.

packages/core/src/entity/EntityTransformer.ts

@@ -15,8 +15,18 @@ export class EntityTransformer {
 
     meta.primaryKeys
       .filter(pk => !Utils.isDefined(entity[pk], true) || !(meta.properties[pk].hidden || ignoreFields.includes(pk)))
-      .map(pk => [pk, Utils.getPrimaryKeyValue<T>(entity, [pk])] as [string, string])
-      .forEach(([pk, value]) => ret[platform.getSerializedPrimaryKeyField(pk) as keyof T] = platform.normalizePrimaryKey(value));
+      .map(pk => {
+        let value: unknown;
+
+        if (Utils.isEntity(entity[pk], true)) {
+          value = EntityTransformer.processEntity(pk, entity, ignoreFields, visited);
+        } else {
+          value = platform.normalizePrimaryKey(Utils.getPrimaryKeyValue<T>(entity, [pk]));
+        }
+
+        return [pk, value] as [string, string];
+      })
+      .forEach(([pk, value]) => ret[platform.getSerializedPrimaryKeyField(pk) as keyof T] = value as unknown as T[keyof T]);
 
     if ((!wrapped.isInitialized() && Utils.isDefined(wrapped.__primaryKey, true)) || visited.includes(wrapped.__uuid)) {
       return ret;
@@ -63,7 +73,7 @@ export class EntityTransformer {
       return EntityTransformer.processCollection(prop, entity);
     }
 
-    if (Utils.isEntity(entity[prop]) || entity[prop] as unknown instanceof Reference) {
+    if (Utils.isEntity(entity[prop], true)) {
       return EntityTransformer.processEntity(prop, entity, ignoreFields, visited);
     }
 

packages/core/src/entity/wrap.ts

@@ -1,6 +1,5 @@
 import { Dictionary, IWrappedEntity, IWrappedEntityInternal } from '../typings';
 import { ArrayCollection } from './ArrayCollection';
-import { WrappedEntity } from './WrappedEntity';
 import { BaseEntity } from './BaseEntity';
 
 /**

tests/composite-keys.mysql.test.ts

@@ -35,7 +35,11 @@ describe('composite keys in mysql', () => {
     await orm.em.persistAndFlush(param);
     orm.em.clear();
 
-    const p1 = await orm.em.findOneOrFail(FooParam2, [param.bar.id, param.baz.id]);
+    // test populating a PK
+    const p1 = await orm.em.findOneOrFail(FooParam2, [param.bar.id, param.baz.id], ['bar']);
+    expect(wrap(p1).toJSON().bar).toMatchObject(wrap(p1.bar).toJSON());
+    expect(wrap(p1).toJSON().baz).toBe(p1.baz.id);
+
     expect(p1.bar.id).toBe(bar.id);
     expect(p1.baz.id).toBe(baz.id);
     expect(p1.value).toBe('val');