In yii2 how can i save multiple related records into db into single save call and single transaction.
I have two tables:

```
User - id, name
UserAddress - id , user_id , city

```

User table has one to many relation to UserAdress table

What i want to do is : 

```
UserAddress ua = new UserAddress();
ua.city = "fff"

User u = new User();
u.name = "test";
u.userAddress = new Array(ua);
u.save();

```

calling save on user should save user and useraddress with user\_id set to user.id as well