我是MongoDB的新手。经过大量搜索之后,我应用了如下所示的汇总操作,并且可以正常运行:
AggregateIterable<Document> summary= collection.aggregate(
Arrays.asList(
Aggregates.match(Filters.eq("financialEventType", "REFUND")),
Aggregates.group("_id",
Accumulators.sum("revenueHeader_Principal","$revenueHeader.Principal"),
Accumulators.sum("revenueHeader_ProductTax","$revenueHeader.Product Tax"),
Accumulators.sum("revenueHeader_Shipping","$revenueHeader.Shipping"),
Accumulators.sum("revenueHeader_ShippingTax","$revenueHeader.Shipping Tax"),
Accumulators.sum("revenueHeader_GiftWrap","$revenueHeader.Gift Wrap"),
Accumulators.sum("revenueHeader_GiftWrapTax","$revenueHeader.Gift Wrap Tax"),)
));
LinkedHashMap<String, BigDecimal> revenueSummary = new LinkedHashMap<String, BigDecimal>();
现在,我想按特定顺序将这些值保存在RevenueSummary中。但是,如何遍历摘要或按名称访问项目?
答案 0 :(得分:0)
您可以使用while
语句进行迭代。
注意::如果有多个结果,则将保存最后个文档值。
MongoCursor<Document> iterator = summary.iterator();
while (iterator.hasNext()) {
Document next = iterator.next();
//Copy from Document key-value
revenueSummary.put("Principal", (BigDecimal) next.get("revenueHeader_Principal"));
revenueSummary.put("ProductTax", (BigDecimal) next.get("revenueHeader_ProductTax"));
//...
}
LINK: https://www.programcreek.com/java-api-examples/index.php?api=com.mongodb.client.AggregateIterable