Html ActionLink run time error: 'Value cannot be null or empty. but value is not null or empty

Question

I am trying to use an @Html.ActionLink for a clickable link in my view, however I get a run time exception:

System.ArgumentException: 'Value cannot be null or empty. Parameter name: linkText

The first param of Html.ActionLink is linkText, and as you can see from my code below, it is indeed not null or empty.

                    @foreach (var o in Model.Results)
                    {
                        <tr>
                            <td>@Html.ActionLink(o.Person.FirstName, "Detail", "Player", new { selectedPlayerID = o.Person.IDPerson, referringController = "ValidationHistory" }, null)</td>
                            <td>@o.Person.FirstName</td>
                            <td>@o.Person.LastName</td>
                            <td>@o.Person.SocialSecurityNumber</td>

Below is a screen shot of the page, at the top I embedded a @(string.IsNullOrWhiteSpace(o.Person.FirstName) ? "null/ws": o.Person.FirstName) as you can see, it is indeed not null or empty.

Per request, below is the entire portion of the cshtml file that pertains to this issue.

<div class="col-md-10 text-center">
    @if (Model.Results.Count == 0)
    {
        <h3>No Data to Display</h3>
        <h3>Please Try Different Search Parameters</h3>
    }
    else
    {
        <div id="tablecontaner" class="col-md-10 text-left">
            <table id="PVSearchReport" class="table table-striped table-bordered" style="width:100%;padding:10px">
                <thead>
                    <tr>

                        <th>First Name</th>
                        <th>Last Name</th>
                        <th>SSN</th>
                        <th>IRS / TIN</th>
                        <th>DMF Details</th>
                        <th>List Matches</th>
                        <th>Executed At</th>
                        <th>Executed By</th>
                        <th>Club ID</th>
                        <th>Lists</th>
                    </tr>
                </thead>
                <tbody>
                    @foreach (var o in Model.Results)
                    {
                        <tr>
                            <td>@Html.ActionLink(o.Person.FirstName, "Detail", "Player", new { selectedPlayerID = o.Person.IDPerson, referringController = "ValidationHistory" }, null)</td>
                            <td>@o.Person.FirstName</td>
                            <td>@o.Person.LastName</td>
                            <td>@o.Person.SocialSecurityNumber</td>

                            <td>@o.Validation_Results.IRSOk</td><!--IRS/TIN-->
                            <td>@o.Validation_Results.DMFOk</td><!--DMF Details-->
                            <td>@o.Validation_Results.ListOk</td><!--List Matches-->
                            <td>@o.Validation_Results.ExecutedAt<!--Executed At-->
                            <td>@o.Validation_Results.ExecutedBy</td><!--Executed By-->
                            <td>@o.Person.ClubID</td>
                            <td>@o.ListMatches</td>
                        </tr>
                    }
                </tbody>        
            </table>
        </div>
    }
</div>

Clearly, FirstName *is* null or empty. I don't understand how we can see from your code that it isn't. Can you elaborate? — Lasse V. Karlsen, Apr 24 '19 at 14:18
It shouldn't be. I handled that on the back end, and it someone was null it should have created a new Person with the name NO NAME. Also it is displaying elsewhere on the page.. I can add some null checking and see if this works. — Jacked_Nerd, Apr 24 '19 at 14:21
Could it be something regarding deserialization, that you did indeed return a person with a first name from the backend, but the frontend somehow didn't deserialize properly so it doesn't have it? — Lasse V. Karlsen, Apr 24 '19 at 14:22
@LasseVågsætherKarlsen This is possible, although I am not sure how I can confirm that? Any Ideas? — Jacked_Nerd, Apr 24 '19 at 14:29
I would still try to simply output the text to the page with something like `@(string.IsNullOrWhiteSpace(o.Person.FirstName) ? "null/ws" : o.Person.FirstName)` and see what it outputs. — Lasse V. Karlsen, Apr 24 '19 at 14:30
I still want to know how we can see from your code that it isn't null or empty. I think you have some assumptions about what your code is supposed to be doing that doesn't hold true. There is no way for us to see from your code what the content of those objects look like, there's no guarantee obvious in that code that this property holds value. Well, other than the fact that it throws an exception at runtime which indicates quite clearly that it doesn't. — Lasse V. Karlsen, Apr 24 '19 at 14:31
@LasseVågsætherKarlsen @(string.IsNullOrWhiteSpace(o.Person.FirstName) ? "null/ws" : o.Person.FirstName) just produced on my screen: NOT NOT NOT Nick Nick NOT NOT Nick NOT NOT NOT NOT NOT NOT NOT Connor Connor Trina Trina Connor John Billie Ramadugula Seiji Mary Trina Jerome Sonya Latanya Lonnie Lovella Leonardo Trina Fabina Billie Seiji Sonya Seiji Leonardo Shelby Leonardo Trina Douglas Connor Kate Kristin KRISTI Fabina Fabina Jay Brian Warren Seiji Alex John Ramadugula Fabina Seiji Seiji Sonya Sonya Connor Billie Sonya Billie Mary John NOT Kristin Connor . . . . . — Jacked_Nerd, Apr 24 '19 at 14:34
@LasseVågsætherKarlsen check my OP, I posted the results of @(string.IsNullOrWhiteSpace(o.Person.FirstName) ? "null/ws" : o.Person.FirstName) to show you — Jacked_Nerd, Apr 24 '19 at 14:39
You should check all cshtml file, may be it show exception at line of code before — Hien Nguyen, Apr 24 '19 at 14:42
@LasseVågsætherKarlsen you were right, somewhere within the 233 results I had a null.. even though I thought I had it accounted for.... — Jacked_Nerd, Apr 24 '19 at 15:18
Possible duplicate of [What is a NullReferenceException, and how do I fix it?](https://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it) — Ian Kemp, Apr 29 '19 at 07:33

Hien Nguyen · Answer 1 · 2019-04-24T14:28:56.210

1

I tried to reproduce it. You need check null before using o?.Person?.FirstName and o?.Person?.IDPerson If C# 5 you can use o.Person.FirstName != null ? o.Person.FirstName : "Default Value" This code worked

  <td>@Html.ActionLink(o?.Person?.FirstName, "Detail", "Player", 
new { selectedPlayerID = o?.Person?.IDPerson, referringController = "ValidationHistory" }, null)</td>

edited Apr 24 '19 at 14:28

answered Apr 24 '19 at 13:50

Hien Nguyen

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If `o` or `o.Person` was null, you'd get a NullReferenceException, not an ArgumentException... – Heretic Monkey Apr 24 '19 at 13:51
1

did you check it? o.Person.FirstName is null that mean ArgumentException – Hien Nguyen Apr 24 '19 at 13:52
@HereticMonkey Since linkText is first argument of ActionLink probably o.Person is null – Paulo Campez Apr 24 '19 at 13:52
1

@PauloCampez `o.Person` is not what you pass to `ActionLink`; you pass `o.Person.FirstName`. `o.Person.FirstName` is what is null, not `o.Person`. – Heretic Monkey Apr 24 '19 at 13:56
O.Person isn't null, I have it displaying fine on the rest of the page. – Jacked_Nerd Apr 24 '19 at 13:56
I did, as others have pointed out, your premise is wrong. If what you're saying is wrong, was wrong, you'd get a NullReferenceException. If you're unable to reproduce a problem you should post a comment, not an answer. – Lasse V. Karlsen Apr 24 '19 at 14:17
What I mean is that instead of posting an answer, you should post a comment on the question, if you're unable to reproduce the problem. If either `o` or `o.Person` was null, OP would get a NullReferenceException, not a ArgumentException. – Lasse V. Karlsen Apr 24 '19 at 14:21
@HienNguyen Just realized I cannot use null propergating operation. I am using C# 5 and this requires version 6 of the language or greater. – Jacked_Nerd Apr 24 '19 at 14:26
If you use C# 5 you can change to o.Person.FirstName != null ? o.Person.FirstName : "Default Value" – Hien Nguyen Apr 24 '19 at 14:28
@HienNguyen ok, thank you for your time. Please check my original post. I have updated it to prove it isn't null, so this fix won't work. – Jacked_Nerd Apr 24 '19 at 14:41
Can you post all cshtml file? may exception from different line of code – Hien Nguyen Apr 24 '19 at 14:43
@HienNguyen Yes, one moment. – Jacked_Nerd Apr 24 '19 at 15:00
@HienNguyen Ok, I did not post entire cshtml file, but this should be all that you need... – Jacked_Nerd Apr 24 '19 at 15:03
is it still exception when you check lastname is null? – Hien Nguyen Apr 24 '19 at 15:06
@HienNguyen no, it's an argument exception for the ActionLink – Jacked_Nerd Apr 24 '19 at 15:08

score 1 · Answer 2 · answered Apr 29 '19 at 07:29

First check Model null or not,Then after check o.Person.FirstName null or not.

        ## Check Model Like: ##

         - @if(Model != null && Model.Count() != 0)
            {
              foreach (var o in Model.Results)
              {
                ---------
              }
            }
        ## Check Record Like: ##
        if(o.Person!=null)
        {
         -----------
        }

score 0 · Answer 3 · answered Apr 24 '19 at 19:41

I was wrong in my original post. There were some empty strings being returned.

To solve:

                        @if (o.Person.FirstName == null || o.Person.FirstName == "" || o.Person.FirstName == "NOT")
                        {
                            <td>Not Found</td>
                        }
                        else
                        {
                            <td>@Html.ActionLink(o.Person.FirstName, "Detail", "Player", new { selectedPlayerID = o.Person.IDPerson, referringController = "ValidationHistory" }, null)</td>
                        }

score 0 · Answer 4 · answered Apr 29 '19 at 07:14

See, You need to check first in loop o.Person this 'Person' object is null or not and other is inside Person object FirstName is null or not, you can handle it like this:

 if(o.Person!=null)
    {
        @Html.ActionLink(o.Person.FirstName ?? "Not Found", "Detail", "Player", new { selectedPlayerID = o.Person.IDPerson, referringController = "ValidationHistory" }, null)
    }

Html ActionLink run time error: 'Value cannot be null or empty. but value is not null or empty

4 Answers4