java – Spring Data返回List

我有这个存储库：

@Repository
public interface ProductRepository extends JpaRepository<Product, Long>{

@Query("SELECT p.textToSearch as text, count(*) as counter FROM Product p GROUP BY text_to_search ORDER BY counter DESC")
List<TopProductDTO> 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<TopProductDTO> topProducts = productRepository.findTopProducts();

它返回一个

List<Object[]> insted a List<TopProductDTO>

就像每列都是列表中对象数组的索引一样……
是不是应该将Spring Data与查询中的’text’和’counter’列绑定到TopProductDTO中的字段？

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 o.a.c.c.C.[.[.[.[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

解决方法:

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<TopProductDTO> findTopProducts();
}

使用班级的完全限定名称.

java – Spring Data返回List

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