Fetch row number MongoDB c#

Question

I am fetching a single candidate exam result details after the examination. which is stored in mongodb using c# driver. The collection has TotalMarks field which is stored with marks obtained in that exam.

Unfortunately the collection does not have the Rank Field because mark calculation is not done in order

What I want to do is order the collection by totalmark and get the position(rank) of the candidate I am selecting.

public ExamCandidateResult ExaminationGetCandidateResultStatus( Guid examinationId, Guid candidateId)
        {
            var con = new MongoClient(DBConnection.ExamConnectionString);
            var db = con.GetDatabase(ExamDB);
            var collection = db.GetCollection<ExamCandidateResult>("Examination");
            var filter = Builders<ExamCandidateResult>.Filter.Eq("ExaminationID", examinationId.ToString())
                       & Builders<ExamCandidateResult>.Filter.Eq("CandidateID", candidateId.ToString());
            var data = collection.Find(filter).FirstOrDefault();
            return data;
        }

With this code I am fetching only the canidate details how can I fetch the rank(row) with it ?

Answer 1

I don't think you can get the row number directly but You can use two queries, one to get the candidate and one to get the count of candidates who have more totalMarks than the desired candidate, and finally plus one count to get the rank of the candidate.