Neo4j 如何从某个起始节点递归删除节点

Question

在我的 Neo4j 数据库中，我有以下实体：

@NodeEntity
public class Product {

    private final static String CONTAINS = "CONTAINS";
    private final static String DEFINED_BY = "DEFINED_BY";
    private final static String VOTED_FOR = "VOTED_FOR";
    private final static String PARENT = "PARENT";
    private final static String CREATED_BY = "CREATED_BY";

    @GraphId
    private Long id;

    @RelatedTo(type = PARENT, direction = Direction.INCOMING)
    private Product parent;

    @RelatedTo(type = CONTAINS, direction = Direction.OUTGOING)
    private Set<Product> childProducts = new HashSet<>();

    @RelatedTo(type = DEFINED_BY, direction = Direction.INCOMING)
    private Set<Criterion> criterias = new HashSet<>();

    @RelatedTo(type = VOTED_FOR, direction = Direction.INCOMING)
    private Set<Vote> votes = new HashSet<>();

    @RelatedTo(type = CREATED_BY, direction = Direction.OUTGOING)
    private User user;

}    

@NodeEntity
public class Criterion {

    private final static String CREATED_BY = "CREATED_BY";
    private final static String DEFINED_BY = "DEFINED_BY";

    @GraphId
    private Long id;

    @RelatedTo(type = DEFINED_BY, direction = Direction.OUTGOING)
    private Product owner;

    @RelatedTo(type = CREATED_BY, direction = Direction.OUTGOING)
    private User user;

}

@NodeEntity
public class Vote {

    private static final String VOTED_ON = "VOTED_ON";
    private final static String VOTED_FOR = "VOTED_FOR";
    private static final String CREATED_BY = "CREATED_BY";

    @GraphId
    private Long id;

    @RelatedTo(type = VOTED_FOR, direction = Direction.OUTGOING)
    private Product product;

    @RelatedTo(type = VOTED_ON, direction = Direction.OUTGOING)
    private Criterion criterion;

    @RelatedTo(type = CREATED_BY, direction = Direction.OUTGOING)
    private User user;

}

Product 是一个复合实体，可以包含子 Products。从层次结构中的某个 Product 节点开始，我需要删除此 Product 上的所有 Votes，然后我需要递归删除所有子 Products、Criteria 定义通过这些节点和 Votes。 User个节点不能删除.

我试过这个 Cypher 查询：

MATCH (p:Product)-[r:CONTAINS*]-(e) WHERE id(p) = {productId} FOREACH (rel IN r| DELETE rel) DELETE e

但它只删除产品，不删除起始节点上的投票以及所有子条件和投票。请帮助我进行正确的 Cypher 查询。谢谢。

Answer 1

我将其分成两个查询。第一个向下递归收集产品层次结构，第二个删除一个产品节点及其直接环境。

获取产品层次结构很简单：

MATCH (p:Product)-[:CONTAINS*]->(childProduct)
WHERE id(p) = {productId}
RETURN id(childProduct) as id

要删除一个产品，我们需要删除该产品节点的所有关系。此外，如果所有相关节点既不是用户（您想保留它们）也不是产品（想想父产品 - 它们也应该保留），则也需要删除它们。我们还需要确保目标节点没有连接，这就是为什么第二个可选匹配：

MATCH (p:Product) 
OPTIONAL MATCH (p)-[r]-(t)
WHERE id(p) = {productId}
DELETE r,p
WITH t
OPTIONAL MATCH (t)-[r2:VOTE_ON|:CREATED_BY]->()
WHERE none(x in labels(t) WHERE x in ["User", "Product"])
DELETE t,r2

我没有亲自测试这个查询，因为你没有提供测试图。所以把这个当成一个idea，修改直到可行。

更新

在一次聊天中我们发现这个cypher语句解决了问题，注意Product已经被模型中的Decision标签所取代：

MATCH (p:Decision) 
WHERE p.name = "NoSQL" 
WITH p 
OPTIONAL MATCH (p)-[r]-(t) 
DELETE p,r 
WITH t,r 
OPTIONAL MATCH (t)-[r2:VOTED_ON|:CREATED_BY|:VOTED_FOR]-() 
WITH t, r2,r 
WHERE none(x in labels(t) WHERE x in ["User", "Decision"]) 
DELETE t,r2

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cypher

spring-data-neo4j

更新