Hibernate搜索6合并了不起作用的投影

Question

我已经实现了Hibernate搜索，目前在投影方面存在问题。所有相关数据都被编入索引，因此我尝试将它们投影到DTO。作为文档(单/#搜索-dsl-投影-合成)，我尝试了以下内容

  searchSession.search(Building.class)
                .select(f -> f.composite(BuildingDto::new,
                        f.field("id", String.class),
                        f.field("name", String.class),
                        f.field("street", String.class),
                        f.field("zip", String.class),
                        f.field("town", String.class)))
                .where(f -> f.wildcard().fields("id", "name", "town", "street", "zip").matching(search))
                .sort(f -> f.field("id").desc())
                .fetch(20);

在运行构建时，我会收到以下错误消息：

java: method composite in interface org.hibernate.search.engine.search.projection.dsl.SearchProjectionFactory<R,E> cannot be applied to given types;
  required: org.hibernate.search.engine.search.projection.dsl.ProjectionFinalStep<?>[]
  found: BuildingDto::new,org.hibernate.search.engine.search.projection.dsl.FieldProjectionValueStep<capture#1 of ?,java.lang.String>,org.hibernate.search.engine.search.projection.dsl.FieldProjectionValueStep<capture#2 of ?,java.lang.String>,org.hibernate.search.engine.search.projection.dsl.FieldProjectionValueStep<capture#3 of ?,java.lang.String>,org.hibernate.search.engine.search.projection.dsl.FieldProjectionValueStep<capture#4 of ?,java.lang.String>,org.hibernate.search.engine.search.projection.dsl.FieldProjectionValueStep<capture#5 of ?,java.lang.String>
  reason: varargs mismatch; bad return type in method reference
      BuildingDto cannot be converted to org.hibernate.search.engine.search.projection.SearchProjection<java.lang.Object>

BuildingDto有以下构造函数：

    public BuildingDto (){}
    public BuildingDto (String id, String name,String street, String zip, String town) {
       //setting vars
    }

Answer 1

编辑:从Hibernate搜索6.2开始，您可以用@ProjectionConstructor注释您的DTO构造器

    @ProjectionConstructor
    public BuildingDto (String id, String name,String street, String zip, String town) {
       //setting vars
    }

确保使用-parameters编译器标志编译代码。

然后，您可以简单地这样做：

  searchSession.search(Building.class)
                .select(BuildingDto.class)
                .where(f -> f.wildcard().fields("id", "name", "town", "street", "zip").matching(search))
                .sort(f -> f.field("id").desc())
                .fetch(20);

更多信息，这里。

原始答案(Hibernate搜索6.1及以下)：

作为在参考文件中解释，类型安全的复合投影目前只能支持三个内部投影.

如果需要更多信息，创建DTO的“转换器”函数将需要接受List<?>并执行一些转换：

  searchSession.search(Building.class)
                .select(f -> f.composite(list -> new BuildingDto(
                                (String) list.get(0),
                                (String) list.get(1),
                                (String) list.get(2),
                                (String) list.get(3),
                                (String) list.get(4)
                        ),
                        f.field("id", String.class),
                        f.field("name", String.class),
                        f.field("street", String.class),
                        f.field("zip", String.class),
                        f.field("town", String.class)))
                .where(f -> f.wildcard().fields("id", "name", "town", "street", "zip").matching(search))
                .sort(f -> f.field("id").desc())
                .fetch(20);

是的，这很难看，但我们正在研究更好的解决方案。