Wpf How to render button dynamically based on variable

Question

I want to be able to display hyperlink if the Url is not null, otherwise I do not wish to display the link.

How shall i go about this? Here is my code so far. Example of my list box template:

<ListBox.ItemTemplate>                            
  <DataTemplate>
   <StackPanel Background="#CD85C9E9" 
            Name="spListItem" 
            Orientation="Horizontal" 
            HorizontalAlignment="Stretch">
     <Label>
       <TextBlock Text="{Binding Name}" />

       <!-- How to define if Url Is Null -->
       <Hyperlink Name="MyLink" Click="MyLink_Click" /> 
    </Label>                                    
  </StackPanel>
 </DataTemplate>
</ListBox.ItemTemplate>

My Class:

public class MyList
{
    public string Name{get;set;}
    public string? Url{get;set;}
}

Tim Rogers · Accepted Answer · 2011-10-27 10:18:04Z

3

Two options:

Write a custom value converter to convert an object (your Url in this case) to a Visibility based on whether it is null or not, and set that on your Visibility property:

Use a DataTrigger to set the visibility to false.

<Hyperlink Name="MyLink" Click="MyLink_Click">
    <Hyperlink.Style>
        <Style TargetType="Hyperlink">
            <Style.Triggers>
                <DataTrigger Binding="{Binding Url}" Value="{x:Null}">
                    <Setter Property="Visibility" Value="Collapsed"/>
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </Hyperlink.Style>
</Hyperlink>

The second is more verbose, but can be done entirely in xaml. However, in the first case, you will end up using the custom converter more than once.

And by the way

public string? Url{get;set;}

String is a reference type so is already nullable.

answered Oct 27, 2011 at 10:18

Tim Rogers

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1 Comment

cpoDesign Over a year ago

like your usage of triggers upping for this...the string, it was just to empesize that is null. your comment made me read up more about triggers

sll · Accepted Answer · 2011-10-27 10:47:37Z

1

I would suggest you following MVVM pattern so all business logic details are encapsulated by ViewModel (or at least keep it in code behind rather than complex View triggers, etc).

So basically you can expose property

public bool IsUrlProvided { get; private set; }

Which encapsulates all logic which is aware of right URL format details and in View just bind Visibility to this flag usng BooleanToVisibilityConverter.

<Button Visibility="{Binding IsUrlProvided, 
                    Converter={StaticResource BooleanToVisibilityConverter}}" />

In this way you do not need to change a View each time as logic changes

edited Oct 27, 2011 at 10:47

answered Oct 27, 2011 at 10:39

sll

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1 Comment

cpoDesign Over a year ago

Simple way.. wonder why i did not thought about it... :) thnx a bunch

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