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Mongo aggregation framework

vinny kapoor
Greenhorn

Joined: Apr 05, 2008
Posts: 13
I wanted to write down my first query using spring's mongo aggregation framework. The query is basically to group by 'field' and then to count the number of occurences.

Something similar to

Select state, count(state)
from <table>
group by (state)

Corresponding query using mongo spring's framework using java:

TypedAggregation<Ticket> aggregation = newAggregation(Ticket.class, group("state").count().as("count"),
project("state").and("count").previousOperation());

AggregationResults<cheese> results = springMongoManager.getDao().aggregate(aggregation, cheese.class);
List<cheese> mappedResults = results.getMappedResults();


where

class cheese {
String state;
long count;
}


The above query clearly is not working.

Any help will be appreciated.
 
It is sorta covered in the JavaRanch Style Guide.
 
subject: Mongo aggregation framework
 
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