multinode treepicker value cannot be null - Using Umbraco And Getting Started

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Nathan Rogan 22 posts 203 karma points

Apr 21, 2020 @ 11:39
0

Multinode Treepicker - Value cannot be null

Using Umbraco And Getting Started

Umbraco 8
Hi, I'm using the following to get MNTP values:
```
@{ var selection = Model.Value<IEnumerable<IPublishedContent>>("tips").ToArray(); }

@if (selection.Length > 0)
{
    <ul>
        @foreach (var item in selection)
        {
            <li>
                <a href="@item.Url">@item.Name</a>
            </li>
        }
    </ul>
}
```
If there's nothing picked I would expect the code not to run but it comes back with an error "System.ArgumentNullException: Value cannot be null." on the selection var. I have also tried .Count() but does the same thing.

Has anyone got any suggestions?

Thanks
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Alex Skrypnyk 6132 posts 23951 karma points MVP 7x admin c-trib

Apr 21, 2020 @ 12:02

Hi Nathan,

If only one item has been selected in MNTP - then you have to use Model.Value

Probably this code should work:

@{ var selection = Model.Value<IEnumerable<IPublishedContent>>("tips").ToArray(); }

@if (selection != null && selection.Length > 0)
{
    <ul>
        @foreach (var item in selection)
        {
            <li>
                <a href="@item.Url">@item.Name</a>
            </li>
        }
    </ul>
}
else
{
    var selectedItem = Model.Value<IPublishedContent>("tips");
    if (selectedItem != null)
    {
        <ul>
            <li>
                <a href="@selectedItem.Url">@selectedItem.Name</a>
            </li>
        </ul>
    }
}

Thanks,

Alex

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Nik 1593 posts 7151 karma points MVP 6x c-trib

Apr 21, 2020 @ 12:25
101
The issue lies in this line:
```
Model.Value<IEnumerable<IPublishedContent>>("tips").ToArray()
```
The .ToArray() will throw an exception if nothing is picked because the .Value request returns Null if nothing is picked, not an empty IEnumerable. And that causes the problem you are seeing. So instead of checking count, you need to check for null.

Thanks

Nik
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Alex Skrypnyk 6132 posts 23951 karma points MVP 7x admin c-trib

Apr 21, 2020 @ 13:23

0

Thanks Nik

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Nathan Rogan 22 posts 203 karma points

Apr 21, 2020 @ 13:46

Thanks both for the quick reply. I have it working now using:

@{ var selection = Model.Value<IEnumerable<IPublishedContent>>("tips"); }


@if (selection != null)
{
    <ul>
        @foreach (var item in selection)
        {
            <li>
                <a href="@item.Url">@item.Name</a>
            </li>
        }
    </ul>
}

Cheers

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Multinode Treepicker - Value cannot be null