Spring Data MongoDB分组投影实现支付类型金额聚合求助

现有3条MongoDB示例记录：

{
  "_id" : "0cc5c468-2105-11ee-ad68-15d467e62by4d",
  "storeId" : "3070",
  "paymentType" : "cash",
  "total" : {"$numberDecimal": "100"}
},
{
  "_id" : "1111111-2105-11ee-ad68-15d467e62by4d",
  "storeId" : "3070",
  "paymentType" : "cash",
  "total" : {"$numberDecimal": "100"}
},
{
  "_id" : "0cc5c468-2105-11ee-ad68-15d467e62by4d",
  "storeId" : "3070",
  "paymentType" : "creditCard",
  "total" : {"$numberDecimal": "50"}
}

期望通过分组投影得到如下格式的输出（最后一列可忽略）：

StoreId | Cash Payment | Card Payment | Total Amount Cash + Card
3070        200               50                250

当前编写的GroupOperation会生成现金支付和信用卡支付两条独立记录，不符合预期：

GroupOperation groupingLogic() {
        return group("storeId", "paymentType")
                .first("storeId").as("storeId")
                .first("paymentType").as("paymentType")
                .sum(TOTAL).as(TOTAL);
    }

需要正确的Java MongoDB实现代码。

正确的做法是仅按storeId分组，使用条件求和分别计算不同支付类型的总额，同时可额外计算总和。以下是实现代码：

import org.springframework.data.mongodb.core.aggregation.Aggregation;
import org.springframework.data.mongodb.core.aggregation.GroupOperation;
import org.springframework.data.mongodb.core.aggregation.ProjectionOperation;
import static org.springframework.data.mongodb.core.aggregation.Aggregation.*;
import static org.springframework.data.mongodb.core.aggregation.ConditionalOperators.when;

public class StorePaymentAggregation {

    private static final String STORE_ID = "storeId";
    private static final String PAYMENT_TYPE = "paymentType";
    private static final String TOTAL = "total";
    private static final String CASH_PAYMENT = "Cash Payment";
    private static final String CARD_PAYMENT = "Card Payment";
    private static final String TOTAL_AMOUNT = "Total Amount Cash + Card";

    public GroupOperation groupingLogic() {
        return group(STORE_ID)
                // 统计现金支付总额：仅累加paymentType为cash的total值
                .sum(when(PAYMENT_TYPE).is("cash").then(TOTAL).otherwise(0)).as(CASH_PAYMENT)
                // 统计信用卡支付总额：仅累加paymentType为creditCard的total值
                .sum(when(PAYMENT_TYPE).is("creditCard").then(TOTAL).otherwise(0)).as(CARD_PAYMENT)
                // 计算所有支付类型的总额（可选）
                .sum(TOTAL).as(TOTAL_AMOUNT);
    }

    // 可选：投影操作，调整输出字段顺序与格式
    public ProjectionOperation projectionLogic() {
        return project(STORE_ID, CASH_PAYMENT, CARD_PAYMENT, TOTAL_AMOUNT)
                .and(STORE_ID).previousOperation();
    }

    // 聚合执行示例
    public void executeAggregation() {
        Aggregation aggregation = newAggregation(
                groupingLogic(),
                projectionLogic() // 按需添加
        );
        // 后续通过mongoTemplate执行聚合，示例：
        // mongoTemplate.aggregate(aggregation, "your-collection-name", PaymentSummary.class);
    }
}

// 对应结果的实体类示例
class PaymentSummary {
    private String storeId;
    private Number cashPayment;
    private Number cardPayment;
    private Number totalAmount;

    // Getter、Setter方法
}

代码说明 #

1. 分组维度调整：仅以storeId作为分组键，确保每个门店只生成一条汇总记录。
2. 条件求和逻辑：通过ConditionalOperators.when判断支付类型，对符合条件的total字段累加，不符合的则加0，实现不同支付类型的单独统计。
3. 可选总和计算：直接使用sum(TOTAL)累加所有支付记录的总额，得到合计值。
4. 投影操作：可选用于规范输出字段的顺序，让结果更贴合期望格式。

内容的提问来源于stack exchange，提问作者jarvo69