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vaspaean
vaspaean

Reputation: 93

MongoDb comparing two fields in same collection, in java

How do I compare two fields in the same collection using Mongo-DB java driver? I need to fetch data in batches and then work on them after proper filtering. Below is the sort of code that I was trying.

MongoCollection<Document> collection = getCollection();
FindIterable<Document> documents = collection.find(
    or(
       lt(field1, 0),
       gt(field2, field3)
    )
)
.projection(Projections.fields(Projections.include(field1)))
    .sort(Sorts.ascending(field1))
    .batchSize(1000).noCursorTimeout(true);

documents.forEach((Block<Document>) document ->{
 // remaining code
}


//Mongo Query

db.example.find( { $or:[{"field1":{$lt:0}}, {"field2":{$gt:"$field3"}}]});

Upvotes: 1

Views: 1499

Answers (1)

HbnKing
HbnKing

Reputation: 1882

there are many way to deal with your problem
firstly you can use $where to do this 

 db.ct_work.find(
{ $or:[{"field1":{$lt:0}},
    {"$where":"this.field2 >= this.field3"}]}) 

## in java  you  do with  Filters.where  or  create  a  DBObject

Filters.where("this.a > this.b") 

DBObject obj = new BasicDBObject();
obj.put("$where", "this.subNum >= this.stuNum");

secondly you can use $expr

## like 
db.monthlyBudget.find( { $expr: { $gt: [ "$spent" , "$budget" ] } } )

you can also use with aggregate with $redact and $cond

$match:{},
 $redact: {
                "$cond": [{
                        "$gt": ["$firstfield", "$secondfiled"}]
                    },
                     "$$KEEP", "$$PRUNE"
                ]
            }

it may helps to you !

Upvotes: 2

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