如何通过使用 JPQL 的枚举 属性 或 spring 数据中的条件 Api 获取自定义数据组？

Question

我有一个枚举来存储货币：

public enum Currency {

    USD,EUR,GBP

}

我有包含货币的销售实体 属性：

public class Sales {

    private Long id;
    private Merchant merchant;
    private Customer customer;
    private double amount;
    private Currency currency;

}

示例table 销售数据如下：

+----+-------------+-------------+--------+----------+
| id | merchant_id | customer_id | amount | currency |
+----+-------------+-------------+--------+----------+
|  1 |           2 |           3 |  125.0 | EUR      |
|  2 |           1 |           2 |  135.0 | USD      |
|  3 |           3 |           5 |  140.0 | GBP      |
|  4 |           2 |           8 |   25.0 | USD      |
|  5 |           4 |           8 |   95.0 | EUR      |
|  6 |           6 |           9 |   85.0 | EUR      |
|  7 |           5 |           6 |   90.0 | USD      |
|  8 |           1 |           1 |  225.0 | EUR      |
|  9 |           7 |           2 |  350.0 | GBP      |
|  . |           . |           . |      . | .        |
|  . |           . |           . |      . | .        |
|  . |           . |           . |      . | .        |
|  . |           . |           . |      . | .        |
+----+-------------+-------------+--------+----------+

这是我的自定义数据模型

    public class CustomDataModel{

      private Integer count; //record count
      private double total; // its total amount for specified currency 
      private Currency currency; //  it also could be String, it is doesn't matter  

}

我的查询参数：merchant_id 和 customer_id.

我想得到结果 List<CustomDataModel> 例如：

[  
   {  
      "count":5,
      "total":674.00,
      "currency":"USD"
   },
   {  
      "count":3,
      "total":561.00,
      "currency":"EUR"
   },
   {  
      "count":4,
      "total":715.00,
      "currency":"GBP"
   }
]

有没有可能得到这样的结果。如果是我该怎么办？

Answer 1

我想你想要 List<CustomDataModel> 按货币分组。如果是这样，则无需依赖 merchant_id 或 customer_id。

您可以在您的存储库中添加以下 @Query 方法，如下所示：

@Query("select new com.demo.spring.domain.CustomDataModel(count(s), sum(s.amount), s.currency) from Sales s group by s.currency")
List<CustomDataModel> getGroupByCurrency();

只需确保将 Integer 转换为 Long，就像在 CustomDataModel class 中的 - private Integer count; 到 private Long count; 并向其添加以下构造函数：

  public CustomDataModel(Long count, double total, Currency currency) {
    super();
    this.count = count;
    this.total = total;
    this.currency = currency;
}

如果你想按商户和客户分组，你可以将上面的group by子句更新为...group by s.currency, s.merchant, s.customer