feat: implement virtuals factory

lib/factories/index.ts

@@ -1,2 +1,3 @@
 export * from './definitions.factory';
 export * from './schema.factory';
+export * from './virtuals.factory';

lib/factories/virtuals.factory.ts

@@ -0,0 +1,24 @@
+import * as mongoose from 'mongoose';
+import { Type } from '@nestjs/common';
+import { TypeMetadataStorage } from '../storages/type-metadata.storage';
+
+export class VirtualsFactory {
+  static createForClass<TClass = any>(
+    target: Type<TClass>,
+    schema: mongoose.Schema<TClass>,
+  ): void {
+    const virtuals = TypeMetadataStorage.getVirtualsMetadataByTarget(target);
+
+    virtuals.forEach(({ options, name, getter, setter }) => {
+      const virtual = schema.virtual(name, options);
+
+      if (getter) {
+        virtual.get(getter);
+      }
+
+      if (setter) {
+        virtual.set(setter);
+      }
+    });
+  }
+}