Cannot fetch child entity (contains) in spring-data-neo4j

Question

Parent class

@Node
@NoArgsConstructor
@AllArgsConstructor
public class Dish {
  @Id
  private String dishName;
  @Relationship(type = "CONTAINS", direction = Relationship.Direction.OUTGOING)
  private List<Ingredient> ingredients;
  private String recipeUrl;
  private String cuisine; // New field for cuisine
  private String dishType; // New field for dish type

  // Getters and Setters for all fields

Child class

@Getter
@Setter
public class Ingredient {
  @Id
  private String nameInEnglish;
  private String nameInHindi;
  private String nameInGerman;

mapping in neo4j

MATCH (d:Dish {dishName: 'Paneer Butter Masala'}),
      (i1:Ingredient {nameInEnglish: 'Paneer'}),
      (i2:Ingredient {nameInEnglish: 'Butter'}),
      (i3:Ingredient {nameInEnglish: 'Tomato'})
CREATE (d)-[:CONTAINS]->(i1),
       (d)-[:CONTAINS]->(i2),
       (d)-[:CONTAINS]->(i3);

neo4j browser returns one dish with one ingredient

    MATCH (d:Dish)-[:CONTAINS]->(i:Ingredient)
    WHERE i.nameInEnglish = "Paneer"
    RETURN d,collect(i) as ingredients

but Java response has 1 dish with an ingredient arraylist always empty in the IntelliJ debugger using query but the neo4j browser

Answer 1

The browser is "lying" to you. In the settings page, there is a option that is checked by default to connect your results:

In reality, your query does not return the relationships but only the Dishes and Ingredients.

For this to work in SDN, you would have to provide the relationships and alter your query into something like this

MATCH (d:Dish)-[r:CONTAINS]->(i:Ingredient)
WHERE i.nameInEnglish = "Paneer"
RETURN d, collect(r), collect(i) as ingredients

Otherwise SDN cannot guess what it should do with the returned Dish and the Ingredients. It will not just connect them because they also could have been connected via another relationship type.