Realm migration: suitable code structure and design pattern

With the progress of an app, the realm migration is increased by a large volume. Is there any optimal design pattern which can significantly reduce the coding for migration? Suppose, I have the following migration:

if (!schema.contains(Subject.class.getSimpleName())) {
                            RealmObjectSchema inputConfigSchema = schema.create(Subject.class.getSimpleName())
                                    .addField("name", String.class)
                                    .addField("difficulty", String.class);

                            if (!schema.get(Student.class.getSimpleName()).hasField("subject")) {
                                schema.get(Student.class.getSimpleName()).addRealmObjectField("subject", inputConfigSchema);
                            }

                        }
                        if (!schema.get(Student.class.getSimpleName()).hasField("age")) {
                            schema.get(Student.class.getSimpleName()).addField("age", Integer.class);
                            schema.get(Student.class.getSimpleName()).setNullable("age", false);
                        }
    }

please suggest a suitable design pattern to optimize this type of realm migration