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Spring Data Neo4j reference文档中关于@RelatedTo注解的注意事项

Ecole_Keine 2015-03-17 13:53 92 查看
源于3.2.2的reference文档

22.5.5.基于结束节点(end node)区分关系
22.5.5. Discriminating Relationships Based
On End Node Type

...

Example 61. Discriminating Relationship Types Using End Node Type

@NodeEntity
class Person {
@RelatedTo(type="OWNS", enforceTargetType=true)
Car car;

@RelatedTo(type="OWNS", enforceTargetType=true)
Pet pet;
...


The example easily generalises to collections too of course, but there are a few note-worthy rules and corner cases:

You need to annotate all clashing relationships.

You can’t have two fields, two collections, or a field and a collection, with the same relationship type and identical end node types. SDN does not store metadata about the origin of a relationship. So when saving the entity, the first field or collection
would be overwritten by the second, with the processing order being non-deterministic.

You can have clashing relation ship types when end nodes share a supertype.

A variation on the above, you cannot have two fields or two collections with the same relationship type and substitutable end node types.

You can however have a field and a collection where end node types inherit from each other.

你需要注解所有冲突的关系

不可有两个字段、集合或一字段一集合,有同样的关系类型及同样的结束节点(end node)类型。

节点类型之间可以有共同基类

两个字段、集合有同样的关系时,节点类型之间不可为可替代的(i.e.互不为继承关系)

然而,一字段一集合时节点类型为继承关系