I have an aggregation:
AggregationResults<Integer> result = mongoTemplate.aggregate(
Aggregation.newAggregation(
Aggregation.group().count().as("value"),
Aggregation.project("value").andExclude("_id"),
MyData.class, Integer.class);
In the mongo shell, when I don't have to map an object, I get: { "value" : 2 }
However, I get the following error when trying to map this lone value: org.springframework.data.mapping.model.MappingException: No mapping metadata found for java.lang.Integer
Can I get around having to create a new output type class, when I only want to get a single java primitive?
Note: I'm going this approach instead of db.collection.count() for the sharding inaccuracies stated here - https://docs.mongodb.com/manual/reference/method/db.collection.count/#sharded-clusters
AggregationResults<DBObject> result = mongoTemplate.aggregate(
Aggregation.newAggregation(
Aggregation.group().count().as("value"),
Aggregation.project("value").andExclude("_id"),
MyData.class, DBObject.class);
int count = (Integer) result.getUniqueMappedResult().get("value");
So, not exactly what I wanted, because I still have to traverse over an object, but it's not any more code than I had before and I didn't need to make another class as the outputType.