CODEWITHSUNDEEP
springmongodbspring-mvc
java_dude
java_dude

Reputation: 4088

Groupby in MongoTemplate returning empty fields

I have a collection with fields id, a-int, b-int, c-int, total-int. I am trying to get a, b, c, total but I end up getting just the sum of total and rest of the field values are 0, 0, 0. How do I fix this? Expected result from the data sample below 10, 20, 30, 300

Thanks

Data sample

id,   a,  b,  c, total
xid, 10, 20, 30, 100
xid, 10, 20, 30, 200


GroupBy groupBy = GroupBy.key("{a : 1, b : 1, c : 1}")
  .initialDocument("{ total: 0 }")
  .reduceFunction("function(obj, result) { result.total += obj.total; }");

GroupByResults<Grouped> results = mongoTemplate.group(Criteria.where("id").is(id),
TABLE, groupBy, Grouped.class);

Upvotes: 0

Views: 1585

Answers (1)

Trisha
Trisha

Reputation: 3931

I've got the result I think you wanted using the following:

GroupBy groupBy = GroupBy.key("a", "b", "c")
                         .initialDocument("{ total: 0 }")
                         .reduceFunction("function(obj, result) { " +
                                         "  result.a = obj.a; " +
                                         "  result.b = obj.b; " +
                                         "  result.c = obj.c; " +
                                         "  result.total += obj.total; " +
                                         "}");

Note that what you need to do is tell the reduce function what to put into the a, b, and c fields as well as the total field.

This gave me a raw output of:

{ "a" : 10.0 , "b" : 20.0 , "c" : 30.0 , "total" : 300.0}

Since you haven't included the Grouped class, I'm not sure if this maps exactly into the object that you wanted, but it might point you in the right direction.

Upvotes: 1

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