Combining Datatemplates at Runtime

Combining DataTemplates at runtime

You could create the DataTemplate dynamically using the XamlReader.Parse or XamlReader.Load method, e.g.:

string template = "<DataTemplate xmlns =\"http://schemas.microsoft.com/winfx/2006/xaml/presentation\" xmlns:x =\"http://schemas.microsoft.com/winfx/2006/xaml\"><StackPanel>[PLACEHOLDER]</StackPanel></DataTemplate>".Replace("[PLACEHOLDER]", "...custom code...");
return System.Windows.Markup.XamlReader.Parse(template) as DataTemplate;

The custom parts could be defined as UserControls.

I am afraid there is no way to base a DataTemplate on another one in pure XAML though.

How to use the same DataTemplate and bind to outside dynamic properties

My question is this: is there any way I use just one DataTemplate and then modify it per column?

Short answer: No, at least not in XAML. You must define a template as a whole. I am afraid you can't "inherit" all parts but the binding.

You may consider creating the templates programmatically:

Is there a way to build a DataTemplate with only C#

Changing data binding in DataTemplateSelector

The LoadContent() method creates an instance of the Image element that you have defined in the template. You are then setting the properties of this specific instance and return the unmodified template that you have defined in the XAML. The Image element that you modify in the SelectTemplate method will then be eligible for garbage collection immediately and will never be used.

So this approach won't work. You need to return a completely different DataTemplate from the method. You can't base a DataTemplate on another one. You might as well get rid of the DataTemplate from your XAML and use the XamlReader.Parse to create a DataTemplate dynamically in your DataTemplateSelector. Check my answer here for an example:

Combining DataTemplates at runtime

Your current approach applies the template and throws away the result.

Is it better to use a bunch of view models/data templates to wrap generic types, or a large data template selector?

but I have not been able to get XAML to recognize a generic type.

You're right, it can't :(.

So I have come up with two options

These are the only two options you have basically. There is not much else to it than what you already discovered I am afraid.

Whether you prefer to define a DataTemplate per "wrapper" type or use a DataTemplateSelector is a matter of personal flavour really. There is no right and wrong.

But your approach - whichever you choose - is the correct one.

Which DataTemplate is selected based on DataType if multiple match

According to the source code of FrameworkElement.FindTemplateResourceInternal, WPF will search resource for DataTemplate by track back the data item's inheritance.

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