Spring Data calling Update instead of Insert when saving with custom primary key

Problem:

You have a class named User with fields like id, email, role, etc. You also have a UserRepository for database operations. When you try to save a new User object with a pre-set id, Spring thinks it's an existing record and tries to update it. But since the record doesn't exist, you get an error TransientDataAccessResourceException.

// A Model class with Custom ID
@Table("users")
public class User {

    @Id
    String id;

    String email;
    String role;


}



public interface UserRepository extends ReactiveCrudRepository<User,String> {


}

// Create an User

User user = User.builder()
                    .id(firebaseUserDetails.getUid())
                    .email(firebaseUserDetails.getEmail())
                    .phone(firebaseUserDetails.getPhoneNumber())
                    .build();
userRepository.save(user);

// throws error 
org.springframework.dao.TransientDataAccessResourceException: 
  Failed to update table [users]; Row with Id [BkYsodTm1kWN8jID36KqnfGLmVJc] 
does not exists

Why this happens:

Spring Data behaves this way because if you set the id field, it assumes that you're working with an existing record, so it tries to update it instead of inserting a new one.

Solution:

You can let Spring know that the record is new and should be inserted, not updated. For this:

1. Make your User class implement the Persistable interface.
2. Add a boolean field, maybe call it isNewEntry, to indicate whether the record is new or existing.
3. Implement the isNew method to return the value of isNewEntry.

@Builder
@Table("users")
public class User implements Persistable<String> {

    @Id
    String id;
    String email;
    String role;
    String phone;
    Long credits;

    // This new field tells us if the record is new
    @Transient
    @Builder.Default
    private boolean isNewEntry = true;

    // This method checks if the record is new
    public boolean isNew() {
        return isNewEntry;
    }
}

Now, when you save a user object with isNewEntry set to true, Spring will insert it as a new record instead of trying to update it.