Use @NodeEntity on interface/abstract class

问题

Is it possible to add @NodeEntity (or even @RelationshipEntity) annotation from SpringData Neo4j on an interface or abstact class or their fields? If not, how do you manage these situations?

回答1:

Definitely you can do that on Abstract classes, and I think it's a good practice in some common cases. Let me give you an example that I'm using in my graph model:

@NodeEntity
public abstract class BasicNodeEntity implements Serializable {

   @GraphId
   private Long nodeId;

   public Long getNodeId() {
      return nodeId;
   }

   @Override
   public abstract boolean equals(Object o);

   @Override
   public abstract int hashCode();
}


public abstract class IdentifiableEntity extends BasicNodeEntity {

   @Indexed(unique = true)
   private String id;

   public String getId() {
      return id;
   }

   public void setId(String id) {
      this.id = id;
   }

   @Override
   public boolean equals(Object o) {
      if (this == o) return true;
      if (!(o instanceof IdentifiableEntity)) return false;

      IdentifiableEntity entity = (IdentifiableEntity) o;

      if (id != null ? !id.equals(entity.id) : entity.id != null) return false;

      return true;
   }

   @Override
   public int hashCode() {
      return id != null ? id.hashCode() : 0;
   }
}

Example of entity idenifiable.

public class User extends IdentifiableEntity {
   private String firstName;
   // ...

   public String getFirstName() {
      return firstName;
   }

   public void setFirstName(String firstName) {
      this.firstName = firstName;
   }
}

OTOH, as far as I know, if you annotate an interface with @NodeEntity, those classes who implement the interface DON'T inherite the annotation. To be sure I've made a test to check it and definately spring-data-neo4j throws an Exception because don't recognize the inherited class neither an NodeEntity nor a RelationshipEntity.

Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'neo4jMappingContext' defined in class org.springframework.data.neo4j.config.Neo4jConfiguration: Invocation of init method failed; nested exception is org.springframework.data.neo4j.mapping.InvalidEntityTypeException: Type class com.xxx.yyy.rest.user.domain.User is neither a @NodeEntity nor a @RelationshipEntity

Hope it helps

回答2:

@NodeEntity or @RelationshipEntity needs to be defined on POJO or concrete classes. Think it same as @Entity in Hibernate. But do you see any valid use case for annotating Interfaces or Abstract Classes?

来源：https://stackoverflow.com/questions/29852608/use-nodeentity-on-interface-abstract-class

标签

neo4j

spring-data

spring-data-neo4j