How to make "Not Equal " using Linq

Question

Hi,
using Sharepoint 2016 On Prem

I have created Linq query to extract data from 2 lists,

Suppose have 2 lists :
List A and , List B

Solution Required: want to retrive those data from list A ,which is not present on list B.

attached is the code image

thanks

Answer 1

Hi @Mohammad Qasim ,

If want to filter out resultUser "m_userid" not equal to resultwfUser "m_wfID", modify to this:

var ListC = resultUser.Select(u=>u.m_userid).Except(resultwfuser.Select(x => x.m_wfID));  

But the above will only return m_userid as using Select.

Another better way will like this:

var ListD = resultUser.Where(a => !resultwfuser.Select(b => b.m_wfID).Contains(a.m_userid));  

This will return the who field which meets condition.

Reference:

Is there a “not equal” in a linq join

Thanks
Best Regards

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Answer 2

Use the Except method to return everything in one list that is not in the second list.

   var listA = new[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };  
   var listB = new[] { 2, 4, 6, 8, 10, 12, 14 };  
     
   var listC = listA.Except(listB);  

Note that it uses equality comparison, like Union and other methods, so it is possible you'll need to define a custom IEqualityComparer implementation to do the comparison based upon the rules you want to use.

In your case you're trying to do this via a join. As discussed in the docs join is equality only. To do a non-equality you can refer to this article but I think Except is easier.