linQ max return null vall

Question

I Have a model like this

public partial class TableNames
{

    public string Name { get; set; }
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.None)] 
    public int IntId { get; set; }
}

Then in a controller I'm Trying to get max IntIdfrom that model

var max = from c in db.TableNames
          select c;

int? Max = max.AsQueryable().Max(x => x.IntId); //This isntruction throws an error
int IntId = ( Max == null ? 1 : Max + 1);

When the table has no records (it's empty) , the controller throws this error

The cast to value type 'Int32' failed because the materialized value is null. 
Either the result type's generic parameter or the query must use a nullable type.

How can I do to fix it ?

The answer to this question might help: http://stackoverflow.com/questions/2165605/whats-the-neatest-way-to-achieve-minordefault-in-linq — Chris Simpson, Dec 12 '12 at 16:59
Nothing, I'm trying your suggestion, but x doesn´t show me HasValue. And the answer you suggestme is asking me for IQueryable. — Juan Pablo Gomez, Dec 12 '12 at 17:09

score 3 · Accepted Answer · answered Dec 12 '12 at 17:16

3

Try this instead:

int? Max = max.AsQueryable().Max(x => (int?)x.IntId);

answered Dec 12 '12 at 17:16

Splendor

1,386
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Excellent .. Tks. for your help. – Juan Pablo Gomez Dec 12 '12 at 18:14

score 3 · Answer 2 · answered Oct 17 '14 at 21:25

3

If you do not wish to deal with Nullable and want a default value (based upon Splendor's code), you may do something similar to the following:

int Max = max.AsQueryable().Max(x => (int?)x.IntId) ?? 1;

answered Oct 17 '14 at 21:25

Trent

335
2
8

score 0 · Answer 3 · answered Dec 12 '12 at 17:20

0

try:

max.Where(i => i.IntId.HasValue).Select(i => i.IntId.Value).Max()

answered Dec 12 '12 at 17:20

lante

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linQ max return null vall

3 Answers3