How to update a DataTemplate dynamically based on a object property?

Question

I have a collection of objects that have different rendering options: They can be simple text, editable text, comboboxes, or event a mixed bag (like a comboBox where items are usually text but with images for specific values).

I managed to show everything correctly by using ContentTemplateSelector inside a ContentPresenter node inside the DataTemplate of the ListViewItem.ItemTemplate:

<ContentPresenter 
    Grid.Row="1"
    Grid.Column="1"
    Content="{Binding .}"
    ContentTemplateSelector="{DynamicResource ResourceKey=RenderTemplateSelector}"/>

(note that everything is inside the DataTemplate of a ListView.ItemTemplate)

All is good until I change the value of said property and need to change the template, for instance going from a image to a text. The VM does update correctly the values, but nothing happens in the GUI.

Looking around here there are a few methods (using a Converter (bound to which property??), defining a Style (i think is not relevant, since i must show different controls, not change properties of the same one), using an AttachedProperty (I don 't understand really well how attached properties work, but from what I saw I should have a ContentControl node, which I don't...) but nothing seems what I need.

So, a recap: I have a ListView that has a DataTemplate definded for each ListViewItem that contains another DataTemplate that needs to change based on a properti of the ListViewItem object. I managed to achieve this with a ContentTemplateSelector, but that is assigned at the beginning and then never changed.

Does this help? https://stackoverflow.com/a/13142699/12107765 — Klamsi, May 25 '21 at 09:56
Or maybe a hack could be deleting and re inserting the item into the list. — Klamsi, May 25 '21 at 09:58
DataTemplates are typically used when you want to want the visual appearence to be specified by the data _type_. I'd need to know more about the specifics of what you're trying to do, but it sounds like what you actually need is for the appearence to be controlled by a _value_. If so, then what you need is a DataTrigger. Either way, the minute you revert to using code-behind, be it in the form of a converter or template selector etc, you're probably doing it wrong! — Mark Feldman, May 25 '21 at 10:05

score 1 · Accepted Answer · answered May 25 '21 at 14:32

You could try to replace the ContentPresenter with a ContentControl that has a Style with data triggers that sets the ContentTemplate, .e.g.:

<ContentControl Content="{Binding}">
    <ContentControl.Style>
        <Style TargetType="ContentControl">
            <Style.Triggers>
                <DataTrigger Binding="{Binding YourProperty}" Value="Type1">
                    <Setter Property="ContentTemplate" Value="{StaticResource template1}" />
                </DataTrigger>
                <DataTrigger Binding="{Binding YourProperty}" Value="Type2">
                    <Setter Property="ContentTemplate" Value="{StaticResource template2}" />
                </DataTrigger>
                <!-- ... -->
            </Style.Triggers>
        </Style>
    </ContentControl.Style>
</ContentControl>

How to update a DataTemplate dynamically based on a object property?

1 Answers1