在 Spring Data Neo4j 中将域对象作为参数传递给自定义 Cypher 查询

问：

我正在编写Spring Data Neo4j webapp。 我有这个域对象：

@Node("Person")
public class Person {
    
    @Id
    @GeneratedValue
    private String id;

和一段关系。(:Image) - [:DEPICTS] -> (:Person)

我需要计算描绘特定人物的图像。 这是我的尝试：

public interface ImageRepositoryNeo4j extends Neo4jRepository<Image, String> {
@Query("""
        MATCH (i:Image) -[:DEPICTS] -> (p:Person)
        WHERE p = $person
        RETURN count(i)
        """)
    // DSNT WORK
    public Integer countByPeopleContains(@Param("person") Person person);

但它总是返回 0。

其他失败的尝试

@Query("""
        MATCH (i:Image)-[:DEPICTS]->(p:Person)
        WHERE p IN $people
        RETURN count(i)
        """)
    // DOESN'T WORK, 0 RESULTS
    public Integer countByPeopleContains(@Param("people") Collection<Person> people);

@Query("""
        MATCH (i:Image) -[:DEPICTS] -> (p:Person)
        WHERE ID(p) = $person.__id__
        RETURN count(i)
        """)
    // DSNT WORK
    public Integer countByPeopleContains(@Param("person") Person person);

@Query("""
        MATCH (i:Image) -[:DEPICTS] -> (p:Person)
        WHERE id(p)=$person
        RETURN count(i)
        """)
    // DSNT WORK
    public Integer countByPeopleContains(@Param("person") String personId);

@Query("""
        MATCH (i:Image) -[:DEPICTS] -> (p:Person {id: $person.__id__})
        RETURN count(i)
        """)
    // DSNT WORK, ALWAYS 0
    public Integer countByPeopleContains(@Param("person") Person person);

它们都返回 0。

这个有效，但由于不是唯一的属性，它不适合域逻辑：fullName

@Query("""
        MATCH (i:Image) -[:DEPICTS] -> (p:Person {fullName: $person})
        RETURN count(i)
        """)
    // TODO: personFullname is not unique, use smth else
    public Integer countByPeopleContains(@Param("person") String personFullName);

如何在Spring Data Neo4j存储库的自定义Cypher查询中使用域对象？

线索

在Spring Data Neo4j文档中，我发现最接近我需要的是：

@Node
public final class Movie {

    @Id
    private final String title;
...
interface MovieRepository extends Neo4jRepository<Movie, String> {

    @Query("MATCH (m:Movie {title: $movie.__id__})\n"
           + "MATCH (m) <- [r:DIRECTED|REVIEWED|ACTED_IN] - (p:Person)\n"
           + "return m, collect(r), collect(p)")
    Movie findByMovie(@Param("movie") Movie movie);
}

但出于某种原因，它在我的情况下不起作用。也许那是因为我的 id 是 .@GeneratedValue

另一条线索

在 Neo4j 嵌入式文档中，有一个关于如何在没有 Spring Data Neo4j 的情况下将对象传递给 Cypher 的示例：

Map<String,Object> params = new HashMap<>();
params.put( "node", bobNode );

String query =
    "MATCH (n:Person)" + "\n" +
    "WHERE n = $node" + "\n" +
    "RETURN n.name";

Result result = transaction.execute( query, params );

它的工作原理是$node：org.neo4j.graphdb.Node

@Bean
CommandLineRunner countForGregWithoutSDN(GraphDatabaseService graphDatabaseService) {
    return args -> {
        try (var tx = graphDatabaseService.beginTx()) {
            String cypherGetGreg = "MATCH (n:Person {birthday: date('1993-03-03')}) RETURN n LIMIT 5;";
            Result result = tx.execute(cypherGetGreg);
            var greg1993 = (Node) result.next().get("n");
            if (!greg1993.getProperty("name").equals("Greg")) 
                throw new RuntimeException("Should be Greg1993 but actually "+greg1993);
            result.close();

            Map<String,Object> params = new HashMap<>();
            params.put( "node", greg1993 );

            String cypherCountForGreg = """
                MATCH (i:Image) -[:DEPICTS] -> (p:Person)
                WHERE p = $node
                RETURN count(i)
                """;
            result = tx.execute( cypherCountForGreg, params );
            var count = result.next().values().iterator().next();
            System.out.println("Count for Greg1993 is "+count); // 1
            result.close();
        }
    };
}

但如果 $node 是 SDN 实体，则结果为 0。