LINQ Max on nullable datatypes

Question

I have an entity as follows.

SchoolDetails

ID Name Rank  School
1  A           Lawrence
2  B      1    Lawrence
3  C      2    Lawrence

I need to fetch the details of student in a particular school(Lawrence) who has highest rank. In this example ID 2 is the desired output.

My linq query is:

var result = SchoolDetails.Where(x=>x.School == "Lawrence").Max(y=>y.Rank).SingleOrDefault();

I get a compliation message saying that "int? doesnt contain a definition for SingleOrDefault"

I cannot change the datatype of Rank column to make it non nullable since it is a production code. So, given this situation how can I fetch a record with highest rank?

https://stackoverflow.com/questions/5047721/linq-max-with-nulls — Roman Ryzhiy, Sep 16 '20 at 06:55
you don't need `SingleOrDefault` after using `Max` max returns the max `int?` and not a `List` — Mohammad Ali, Sep 16 '20 at 06:56
@user1907849 you can do order by Rank descending and get first element — Mohammad Ali, Sep 16 '20 at 06:58
@user1907849 then you need to get first the Max value of Rank and use it as comparison in your filter. You can write the filter directly into the SingleOrDefault method — Mong Zhu, Sep 16 '20 at 06:58

score 3 · Accepted Answer · answered Sep 16 '20 at 07:00

3

Try the below

var result = SchoolDetails.Where(x=>x.School == "Lawrence").OrderByDescending(x => x.Rank).FirstOrDefault();

answered Sep 16 '20 at 07:00

Mohammad Ali

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LINQ Max on nullable datatypes

1 Answers1