"OR " condition in where clause of linq query is returning null

Question

The following code when executed individually is executing properly but when an or condition is included to club both the condition in single query its returning null

userSessionList = userSessionList.Where(u => 
            (u.User.FirstName.ToLower().Contains(name)) || 
            (u.User.LastName.ToLower().Contains(name))
        )
        .ToList();

An `||` cannot filter out matches that existed prior to it. It can only add matches. It can introduce an exception though which may be hidden by your `catch()` that does nothing, such as a `NullReferenceException` on `u.User.LastName.ToLower()`. — GSerg, Dec 12 '19 at 10:19
yes I am getting object NullReferenceException. Can you please suggest how to write this query exactly. — Manjunath M.R, Dec 12 '19 at 10:29
`yes I am getting object NullReferenceException` - would have been very helpful if you mentioned that in the question instead of saying the query is returning null. — GSerg, Dec 12 '19 at 10:31

score 1 · Answer 1 · answered Dec 12 '19 at 10:23

Try with this and see if it works:

   userSessionList = userSessionList.Where(u => 
        (u.User != null && u.User.FirstName != null && u.User.FirstName.ToLower().Contains(name)) || 
        (u.User != null && u.User.LastName != null && u.User.LastName.ToLower().Contains(name))
    )
    .ToList();

You can also run for testing purposes the following in the same execution and see the results

    var userSessionList1 = userSessionList.Where(u => 
        (u.User.FirstName.ToLower().Contains(name))
    )
    .ToList();

    var userSessionList2 = userSessionList.Where(u => 
        (u.User.FirstName.ToLower().Contains(name))
    )
    .ToList();

    var userSessionListBoth = userSessionList.Where(u => 
        (u.User.FirstName.ToLower().Contains(name)) || 
        (u.User.LastName.ToLower().Contains(name))
    )
    .ToList();

And check the three different list. I think that because you are overriding the existing list, it might be that you have done it again in a previous query and that's why you have this weird situation.

Thanks a lot checking for the null condition worked. – Manjunath M.R Dec 12 '19 at 10:39 — Manjunath M.R, Dec 12 '19 at 10:39

score 1 · Accepted Answer · answered Dec 12 '19 at 10:30

1

Use Null-conditional operators

userSessionList = userSessionList.Where(u => 
            (u.User?.FirstName?.ToLower().Contains(name) == true) || 
            (u.User?.LastName?.ToLower().Contains(name) == true)
        )
        .ToList();

answered Dec 12 '19 at 10:30

dovid

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score -1 · Answer 3 · answered Dec 12 '19 at 10:21

-1

You could use the String.IndexOf Method and pass StringComparison.OrdinalIgnoreCase as the type of search to use:

culture.CompareInfo.IndexOf(u.User.LastName, name, CompareOptions.IgnoreCase) >= 0

answered Dec 12 '19 at 10:21

Nguyễn Văn Phong

11,572
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Thank you but I am concerned about returning list of users which matches given condition – Manjunath M.R Dec 12 '19 at 10:32
@ManjunathM.R And this tries to show you how to do it correctly, without involving `ToLower`. – GSerg Dec 12 '19 at 10:32

"OR " condition in where clause of linq query is returning null

3 Answers3