Spring Data返回List

我有这个存储库：

@Repository public interface ProductRepository extends JpaRepository{ @Query("SELECT p.textToSearch as text, count(*) as counter FROM Product p GROUP BY text_to_search ORDER BY counter DESC") List findTopProducts(); } 

TopProductDTO类的位置是：

 public class TopProductDTO { public TopProductDTO() {} private String text; private Integer counter; // Getters and Setters are omited } 

但是当我执行代码时

 List topProducts = productRepository.findTopProducts(); 

它返回一个

 List insted a List 

就像每列都是列表中对象数组的索引一样…… Spring Data是否应该将查询中的’text’和’counter’列与TopProductDTO中的字段绑定？

结果我的Thymeleaf模板中出现了这个错误：

 00:37:22.659 [http-nio-8080-exec-5] ERROR oaccC[.[.[.[dispatcherServlet] - Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.thymeleaf.exceptions.TemplateProcessingException: Exception evaluating SpringEL expression: "topProductDTO.text" (products/top:46)] with root cause org.springframework.expression.spel.SpelEvaluationException: EL1008E:(pos 14): Property or field 'text' cannot be found on object of type 'java.lang.Object[]' - maybe not public? 

我正在使用Spring Boot 1.3.3和Postgres 9.2

Answer 1

尝试使用DTO的构造函数。

声明一个新的构造函数

 public TopProductDTO(String text, Integer count) { this.text = text; this.count = count; } 

在您的查询中使用新的构造函数

 @Query("SELECT new TopProductDTO(p.textToSearch, count(id))FROM Product p GROUP BY text_to_search ORDER BY counter DESC") List findTopProducts(); } 

使用class级的完全限定名称。