需要帮助将 Neo4j Cypher 请求转换为 JPQL

Question

我有需要转换为 JPQL 的 Neo4j Cypher 请求：

MATCH (p:Person)-[:worksForOrganisation]->
    (:Organisation)-[*0..2]->(:Organisation)
    -[:possessesResource|:accessesResource|:supportsResource]->(:Software)
    <-[:categoryContains]-(c:ResourceCategory)
WHERE id(p)=({personId})
RETURN c

此请求从唯一的Person 开始，标识符为personId。

我们知道此人为一个（在极少数情况下，很多）Organisations 工作。

我们知道每个组织都可以拥有、访问或支持Software 类型的资源。

鉴于不同组织之间可能存在关联，我们希望返回“包含”该人可以使用的Softwares 的ResourceCategories，从而授予他/她使用来自另一个组织。

将其转换为 JPQL 的困难来自：

1. (:组织)-[*0..2]->(:组织)
2. (:组织)-[:possessesResource|:accessesResource|:supportsResource]->(:软件)

第 1 点：(:Organisation)-[*0..2]->(:Organisation) 表示最多三个“组织”节点之间的可选关系。这个想法是，在找到一个“组织”节点后，我们还对从最多两个其他“组织”开始的所有路径感兴趣，这些“组织”与该人所在的组织相关联。

第 2 点：(:Organisation)-[:possessesResource|:accessesResource|:supportsResource]->(:Software) 表示，找到一个“组织”后，它可以与具有三种关系的“软件”相关联（甚至可以通过多种关系)。

到目前为止我的想法（我知道真的不完整）：

@Query("SELECT rc FROM Person p, Organisation o1, Organisation o2, Organisation o3, Software s, ResourceCategory rc " +
        "WHERE p.id = :personId " +
        "AND o1 MEMBER OF p.worksForOrganisations " +
        "AND s MEMBER OF rc.resources")
Set<ResourceCategoryEntity> getCategoriesForPerson(@Param("personId") Long personId);

问题：

• 如何重现 [*0..2] 可选关系？我是否需要在三个请求之间使用 UNION，一个仅包含组织 o1，第二个包含组织 o1 和 o2，最后一个包含组织 o1、o2 和 o3？
• 各种关系能否转换为“AND ((s MEMBER OF o1.possessesResource) OR (s MEMBER OF o1.accessesResource) OR (s MEMBER OF o1.supportsResource r))”？

谢谢！

更新：作为JPQL doesn't support UNION，那么如何重现“可变长度连接”？

Answer 1

经过大量工作，我们相信我们找到了相应的 JPQL 请求。

如果有人想知道如何模仿 Cypher 请求的困难部分，即可变长度路径 (Organisation)-[*0..2]->(Organisation)，我相信我们在 JPQL 中根本无法做到，我们必须处理所有可能的实例超类“组织”，分别是“社区”、“机构”、“教学部门”和“行政部门”。

SELECT DISTINCT (rc) FROM ResourceCategory rc JOIN rc.resources d
WHERE d.id IN ( SELECT e.id FROM Documentation e, Organisation o, Person u
                WHERE u.id = :personId
                  AND o MEMBER OF u.worksForOrganisations
                  AND (   o = e.organisationPossessingResource
                       OR o = e.organisationSupportingResource
                       OR o MEMBER of e.organisationsHavingAccessToResource
                      )
              )
   OR d.id IN ( SELECT d.id FROM Documentation d, Organisation o
                WHERE TYPE(o) IN (Institution)
                  AND (   o = d.organisationPossessingResource
                       OR o = d.organisationSupportingResource
                       OR o MEMBER of d.organisationsHavingAccessToResource
                      )
                  AND o.id IN (
                     SELECT i.id FROM Institution i, AdministrativeDepartment ad, Person u
                     WHERE u.id = :personId
                       AND ad MEMBER OF u.worksForOrganisations
                       AND ad MEMBER OF i.administrativeDepartments
                     )
               )
   OR d.id IN ( SELECT d.id FROM Documentation d, Organisation o
                WHERE TYPE(o) IN (Institution)
                  AND (   o = d.organisationPossessingResource
                       OR o = d.organisationSupportingResource
                       OR o MEMBER of d.organisationsHavingAccessToResource
                      )
                  AND o.id IN (
                     SELECT i.id FROM Institution i, TeachingDepartment td, Person u
                     WHERE u.id = :personId
                       AND td MEMBER OF u.worksForOrganisations
                       AND td MEMBER OF i.teachingDepartments
                     )
              )
   OR d.id IN ( SELECT d.id FROM Documentation d, Organisation o
                WHERE TYPE(o) IN (Community)
                  AND (   o = d.organisationPossessingResource
                       OR o = d.organisationSupportingResource
                       OR o MEMBER of d.organisationsHavingAccessToResource
                      )
                  AND o.id IN (
                     SELECT c.id FROM Community c, Institution i, AdministrativeDepartment ad, Person u
                     WHERE u.id = :personId
                       AND ad MEMBER OF u.worksForOrganisations 
                       AND ad MEMBER OF i.administrativeDepartments
                       AND c MEMBER OF i.communities
                     )
              )
   OR d.id IN ( SELECT d.id FROM Documentation d, Organisation o
                WHERE TYPE(o) IN (Community)
                  AND (   o = d.organisationPossessingResource 
                       OR o = d.organisationSupportingResource 
                       OR o MEMBER of d.organisationsHavingAccessToResource
                      )
                  AND o.id IN (
                     SELECT c.id FROM Community c, Institution i, TeachingDepartment td, Person u
                     WHERE u.id = :personId
                       AND td MEMBER OF u.worksForOrganisations
                       AND td MEMBER OF i.teachingDepartments
                       AND c MEMBER OF i.communities
                  )
              )
   OR d.id IN ( SELECT d.id FROM Documentation d, Organisation o
                WHERE TYPE(o) IN (Community)
                  AND (   o = d.organisationPossessingResource
                       OR o = d.organisationSupportingResource
                       OR o MEMBER of d.organisationsHavingAccessToResource
                      )
                 AND o.id IN (
                     SELECT c.id FROM Community c, Institution i, Person u 
                     WHERE u.id = :personId 
                       AND i MEMBER OF u.worksForOrganisations 
                       AND i MEMBER OF c.institutions
                     )
              )

脚注：这表明 Cypher 绝对摇滚，比等效的 JPQL 简单得多。希望它会成为一种标准，所以我不得不切换到关系数据库的原因有一天会消失。