How to save AggregateIterable<Document> values to a map in mongodB?

Question

I am new to MongoDB. After a lot of searches, I have applied an aggregate operation as below and it's working as expected:

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>();

Now I want to save these values in revenueSummary in a specific order. But how do I iterate over summary or access the items by their name?

Answer 1

You may iterate with the while statement.
Note: If there are more than 1 results, you will save the last document values.

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