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I've two entities Person, Employee and Employee1. I want to implement entities inheritance in Spring Data MongoDB. Like in Spring Data JPA, what are the equivalent annotations for @Inheritance and @PrimaryKeyJoinColumn in Spring Data MongoDB. Right now, I've implemented something like this:

interface Person {
    String getId();
    void setId(String id);

    String getName();
    void getName(String name);
}

@Document(collection = "person")
class PersonImpl implements Person {
    @Id
    String id;
    // Getters and setters 
    // Constructors, equals, hashcode and toString methods
}

interface Employee extends Person {
    int getNumberOfDependents();
    void getNumberOfDependents(int numberOfDependents);
}

@Document(collection = "employee")
class EmployeeImpl extends PersonImpl implements Employee {
    // Getters and setters 
    // Constructors, equals, hashcode and toString methods
}

interface Employee1 extends Person {
    int getNumberOfDependents();
    void getNumberOfDependents(int numberOfDependents);
}

@Document(collection = "employee1")
class Employee1Impl extends PersonImpl implements Employee1 {
    // Getters and setters 
    // Constructors, equals, hashcode and toString methods
}

Repository structure:
public interface PersonRepository extends MongoRepository<Person, String> {
}

public interface EmployeeRepository extends MongoRepository<Employee, String> {
}

public interface Employee1Repository extends MongoRepository<Employee1, String> {
}

I'm saving the Person object first and then taking the ID of it and creating an Employee object with the same ID and saving it. This creates new object and hence I'm losing all the Person object stuff. I also feel that I've to get the NoRepositoryBean implemented also. I'm confused. Please help.

User1230321
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    See if this helps. http://stackoverflow.com/q/41145881/2683814 – s7vr Apr 26 '17 at 00:03
  • @Veeram: 1). what is the reason behind not making the extended class a document? In my case I'll have to query on few fields in the extended class. So I want to make it a document. 2). After I create an Employee object and save it, how do I create Employee1 object with the same User object? Because, in Spring Data JPA we will have id in the sub class, for which we will attach already created base object ID and save. Here there is no ID in the sub class. – User1230321 Apr 26 '17 at 04:32

2 Answers2

3

Here is one approach:

@Document(collection = "person")
class Person {
    @Id
    String id;
    // Getters and setters 
    // Constructors, equals, hashcode and toString methods
}

Note that the collection field refers to "person" and not to "employee"

@Document(collection = "person")
class Employee extends Person {
    String jobTitle;
    // Getters and setters 
    // Constructors, equals, hashcode and toString methods
}

In this method you do not need to create a repository for each derived class

@Repository
public interface PersonRepository extends MongoRepository<Person, String> {}

Code example:

@Autowired
private PersonRepository personRepo;

public void test() {
  Employee employee = new Employee("1", "teacher")
  personRepo.save(employee)

  Optional<Person> optionalPerson = personRepo.findById("1");
  Employee employeeFromDb;
  if (optionalPerson.isPresent()) {
     employeeFromDb = (Employee)optionalPerson.get()
  }
  else {
     // could not find in db
  }
}
Uri Loya
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0

if you want to find all employees you should have a methode on MongoRepository called

List<Employee> findAll();
Anas Darrazi
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