Spring Data JPA Query by Example，可以访问嵌套的对象属性

Question

我使用 Query by Example 并想知道如何在嵌套对象中找到具有某些属性的对象。

任何人的计划？

这是我的示例代码:

    ExampleMatcher matcher = ExampleMatcher.matching()
      .withMatcher("offer2product.id.productId", match -> match.exact()
              );

    Offer2ProductId id = new Offer2ProductId();
    id.setProductId(1337L);

    Offer2Product offer2Product = new Offer2Product();
    offer2Product.setId(id);

    Set<Offer2Product> offer2productSet = new HashSet<>();
    offer2productSet.add(offer2Product);

    Offer probe = new Offer();
    probe.setOffer2productSet(offer2productSet);

    Example<Offer> example = Example.of(probe, matcher);
    List<Offer> offerList = offerRepository.findAll(example);

Answer 1

引用 Spring 数据文档:https://docs.spring.io/spring-data/jpa/docs/current/reference/html/#query-by-example

Currently, only SingularAttribute properties can be used for property matching.

在您的示例中，您希望按 Set<> ( offer2productSet ) 的属性进行搜索，即 PluralAttribute - 无法按此字段进行搜索。构建查询时它将被忽略，如下所示:

https://github.com/spring-projects/spring-data-jpa/blob/master/src/main/java/org/springframework/data/jpa/convert/QueryByExamplePredicateBuilder.java#L112