I want to do sum aggregation of a salary which is stored as String in document. I dont want to convert the string value to int in database itself. Something like below in mongoDB using java driver.
SELECT sum(CAST(amount AS UNSIGNED)) FROM tbl1
I tried to cast in acumulator as follows but its giving zero as output.
accumulator = Accumulators.sum("value", $toInt: "$"+field);
I can do it in native mongodb query but I want to do it in java driver.
List<Bson> pipeline = Arrays.asList(group(new BsonNull(), sum("total", eq("$toInt", "$value"))));
AggregateIterable<Document> result = collection.aggregate(pipeline);
The static imports are from the com.mongodb.client.model package.
Optionally, since you are accumulating money, you can consider $toDecimal or $toDouble instead of $toInt.
com.mongodb.client.model.Filters class. eq is a static method. Also, Aggregates.group and Accumulators.sum.
eq mean "equal" here? Why could it apply $toDecimal to a field?$toInt operator is applied to the documentproperty value and assigned to the field total. The definition of Filters.eq. says: "Note that this doesn't actually generate a $eq operator, as the query language doesn't require it."$toDecimal to sum, and get the result as the same data type. Note that MongoDB supports 4 types of number fields - int, long, double and NunberDecimal. And the default for a number type is a double or an int (depends upon the version of MongoDB and the size of the number).