Group by linq query result exception issue

Question

I am trying to group by my results and the check null but it throwing error on .Any() or .Count() and someDocs is in memory collection

var devices = someDocs.SelectMany(x => x.Devices).GroupBy(x => x.type);

if (devices != null && devices.Count()>0) // Exception : Object not set to instance of Object 
{
   //my code 
}

How can I check that grouped result is null?

score 0 · Answer 1 · answered Apr 01 '14 at 05:50

0

Check if someDocs is not not, before doing a linq query over it.

Also check this

GroupBy(x => x.type!= null )

answered Apr 01 '14 at 05:50

maxspan

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score 0 · Answer 2 · answered Apr 01 '14 at 05:55

0

to Determines whether a sequence contains any elements.

if (devices != null && devices.Any() ) 
{

}

answered Apr 01 '14 at 05:55

Damith

62,401
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I used this but but got same exception – Govind Malviya Apr 01 '14 at 05:56
is it! but how! can you please add full stack trace of the exception – Damith Apr 01 '14 at 05:59

score 0 · Answer 3 · answered Apr 01 '14 at 06:07

Are you perhaps getting the exception because someDocs is null? In the code that you posted, at first sight, this is the only place that this exception could be thrown.

Try this:

if(someDocs == null){
 someDocs = new List<TypeOfSomeDocsElement>();
}
var devices = someDocs.SelectMany(x => x.Devices).GroupBy(x => x.type);

if (devices != null && devices.Count()>0) // Exception : Object not set to instance of Object 
{
   //my code 
}

Deidah · Answer 4 · 2018-02-20T13:32:15.033

-1

var devices = someDocs.SelectMany(x => x.Devices)
                      .Where(x.type!=null)
                      .GroupBy(x => x.type);

edited Feb 20 '18 at 13:32

answered Feb 16 '18 at 17:35

Deidah

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Group by linq query result exception issue

4 Answers4