Spring boot mongo - How to refer to document in other collections from a collection

Question

I have Office object:

class Office{
   String address;
   int employees;
   String city;
   String State;
   ---- lot of other fields
}

I have mongo collections for Office class that have lets say 100 Office documents represented by above Office class.

Then I have Employee class:

class Employee{
   String firstName;
   String lastName;
   Office office;
   -----other fields
}

In mongo collection for Employee class how I can prevent Office object to be copied for each Employee entry.

In spring-boot mongodb is there way I can refer to Office collection to represent Office object of Employee instead of copying it for each employee in mongo db. I hope I have explained my problem.

Thanks in advance.

Answer 1

You can use the DBRef in Mongo. Spring Data brings an annotation for that:

@DBRef

But, be careful, MongoDB is a document-oriented NoSQL and is a good practice to embed stuff inside a document. This approach can lead you to a bigger problem.

Edit:

Use the @DBRef like this: https://docs.spring.io/spring-data/data-mongo/docs/1.7.0.RELEASE/reference/html/#mapping-usage-references

Answer 2

Here is the code which you can use:

@Document(collection="person")
public class Person
{

        @Id
        private Long personId;

        private String name;

        private int age;

        @DBRef(db="address")
        private List<Address> addresses = new ArrayList<Address>();

//other getters and setters

}