Java 在JPQL中使用NEW时未初始化列表

我有一个相当简单的查询，它接受一些表的输入。当我尝试运行查询时，它会显示：

[ERROR] org.apache.catalina.core.ContainerBase.[Tomcat].[localhost].[/].   
[dispatcherServlet] - Servlet.service() for servlet [dispatcherServlet] in 
context with path [] threw exception [Request processing failed; nested 
exception is org.springframework.dao.InvalidDataAccessApiUsageException: 
org.hibernate.QueryException: could not instantiate class 
[com.htd.domain.ShopOrder] from tuple; nested exception is 
java.lang.IllegalArgumentException: org.hibernate.QueryException: could not 
instantiate class [com.htd.domain.ShopOrder] from tuple] with root cause  
java.lang.IllegalArgumentException: null

JPQL查询：

@Query("SELECT NEW com.htd.domain.ShopOrder(po.id, po.po_number, "
            + "po.due_date, po_part.id, po_part.part_quantity, "
            + "part.id, part.part_number, part.part_description, "
            + "part.plasma_hrs_per_part, part.grind_hrs_per_part, "
            + "part.mill_hrs_per_part, part.brakepress_hrs_per_part) "
            + "FROM Po po "
            + "LEFT JOIN po.partList po_part "
            + "LEFT JOIN po_part.part part "
            + "LEFT JOIN po_part.part where po.id = ?1")
    List<ShopOrder> getShopOrder(Long id);

我创建了一个Juint测试，通过执行以下操作来查看发生了什么：

@Test
@Transactional
public void shopOrderTest() throws Exception
{

        Po po = new Po();
        Long id = (long) 11;
        LocalDate date = new LocalDate(2015,6,10);
        po.setDue_date(date);
        po.setId(id);
        po.setPo_number("11254");
        po.setSales_order_number("34879");
        po.setStatus("ordered");
        BigDecimal total_sale = new BigDecimal("55");
        po.setTotal_sale(total_sale);

        Part part = new Part();
        BigDecimal brakepress_hrs_per_part = new BigDecimal("34");
        part.setBrakepress_hrs_per_part(brakepress_hrs_per_part);
        BigDecimal grind_hrs_per_part = new BigDecimal("354");
        part.setGrind_hrs_per_part(grind_hrs_per_part);
        part.setId(id);
        part.setInventory_count(55);
        BigDecimal laser_hrs_per_part = new BigDecimal("987");
        part.setLaser_hrs_per_part(laser_hrs_per_part);
        BigDecimal lb_per_part = new BigDecimal("58748");
        part.setLb_per_part(lb_per_part);

        poRes.save(po);
        partRes.save(part);

        List<ShopOrder> getOrders = po_partRepository.getShopOrder(id);

        int size = getOrders.size();

        System.out.println("The size is-----"+size);

        for(ShopOrder order: getOrders){
            System.out.println(order);
        }
    }

}

我希望这能澄清我的疑问。如果你对我应该如何做一个更好的查询有任何建议，我洗耳恭听

下面是我的数据库表的图片：

@Query("SELECT NEW com.htd.domain.ShopOrder(pp.po.id, pp.po.po_number, pp.po.due_date, pp.id, pp.part_quantity, "
        + "pp.part.id, pp.part.part_number, pp.part.part_description, pp.part.plasma_hrs_per_part, pp.part.grind_hrs_per_part, "
        + "pp.part.mill_hrs_per_part, pp/part.brakepress_hrs_per_part) "
        + "FROM Po_part pp Where pp.part.id = ?1")
List<ShopOrder> getShopOrder(Long id);

@Query（“选择新的com.htd.domain.ShopOrder（pp.po.id，pp.po.po\u编号，pp.po.due\u日期，pp.id，pp.part\u数量，”
+“pp.part.id、pp.part.part\u编号、pp.part.part\u描述、pp.part.plasma\u hrs\u每个零件、pp.part.grind\u每个零件，”
+pp.part.mill每个零件工时，pp/part.brakepress每个零件工时）
+“来自Po_零件pp，其中pp.part.id=？1”）
列出getShopOrder（长id）；

无连接

@Query("SELECT NEW com.htd.domain.ShopOrder(po.id, po.po_number, po.due_date, po_part.id, po_part.part_quantity, "
        + "part.id, part.part_number, part.part_description, part.plasma_hrs_per_part, part.grind_hrs_per_part, "
        + "part.mill_hrs_per_part, part.brakepress_hrs_per_part) "
        + "FROM Po po "
        + "LEFT JOIN Po_part po_part ON po_part.po.id = po.id"
        + "LEFT JOIN Part part ON po_part.part.id = part.id AND po.part.id = ?1")
List<ShopOrder> getShopOrder(Long id);

@Query（“选择新的com.htd.domain.ShopOrder（采购订单编号、采购订单编号、采购订单到期日期、采购订单零件编号、采购订单零件数量，”
+零件号、零件号、零件号、零件说明、零件号、零件号、零件号、零件号、零件号、零件号
+“零件轧机每零件工时，零件制动器每零件工时”
+“来自Po Po”
+“在Po_part.Po.id=Po.id上左连接Po_part Po_part”
+“在po_Part.Part.id=Part.id和po.Part.id=1上左连接零件”
列出getShopOrder（长id）；

---

在方法中使用Left join

时，您正在测试

shopOrders

是否为null，但随后您使用的是

shopOrders.toString（）

，这将导致NPE。但这并不是你的查询失败的原因。您的查询被保留两次。这有什么原因吗？此外，是否有可能不存在任何连接关系？如果是这样的话，你可能想让他们加入，而不是左加入。还有，“这起作用了！！！！”消息的相关性是什么？@DuncanKinnear我已经更新了我的帖子。我希望这能把事情弄清楚。@DuncanKinnear我删除了“它起作用了！！！！”的消息。这只是为了调试的目的，我在上传这篇文章之前忘了删除它。你还没有说为什么你在查询中两次

离开了JOIN po_part.part

。尝试删除紧靠

where

前面的第二个。

@OneToMany(mappedBy="po",targetEntity=Po_part.class)
private List<Po_part> partList;


public List<Po_part> getPartList() {
    return partList;
}

@OneToMany(mappedBy="part",targetEntity=Po_part.class)
private List<Po_part> partList;

@ManyToOne
private Part part;

@ManyToOne
private Po po;

@Query("SELECT NEW com.htd.domain.ShopOrder(pp.po.id, pp.po.po_number, pp.po.due_date, pp.id, pp.part_quantity, "
        + "pp.part.id, pp.part.part_number, pp.part.part_description, pp.part.plasma_hrs_per_part, pp.part.grind_hrs_per_part, "
        + "pp.part.mill_hrs_per_part, pp/part.brakepress_hrs_per_part) "
        + "FROM Po_part pp Where pp.part.id = ?1")
List<ShopOrder> getShopOrder(Long id);

@Query("SELECT NEW com.htd.domain.ShopOrder(po.id, po.po_number, po.due_date, po_part.id, po_part.part_quantity, "
        + "part.id, part.part_number, part.part_description, part.plasma_hrs_per_part, part.grind_hrs_per_part, "
        + "part.mill_hrs_per_part, part.brakepress_hrs_per_part) "
        + "FROM Po po "
        + "LEFT JOIN Po_part po_part ON po_part.po.id = po.id"
        + "LEFT JOIN Part part ON po_part.part.id = part.id AND po.part.id = ?1")
List<ShopOrder> getShopOrder(Long id);