[DataTemplate][Windows] Property Not Found Exception at Styles/Generic.xaml

[DevTKSS]

Current behavior

Somehow Xaml Compiler does not find a Property in a DataTemplate Definition there, but its not altering from all the other DataTemplate Definitions, imported as ResourceDictionary and should be fine...

Expected behavior

Should not throw issue?

How to reproduce it (as minimally and precisely as possible)

Build the app from this commit: DevTKSS/DevTKSS.Uno.SampleApps@50db97b

(will apply workaround meanwile I dont know the problem source at later commits)

Workaround

as they has been in the page resources that was not happening, so will revert those Refactoring to that central StaticResource as Workaround
Not Rebuild or Build Solution only run debug?

Works on UWP/WinUI

Debug Run target Desktop builds, but "(Re)build Solution" after "Clean Solution" does throw this issue only for the additional Windows target, which is not targeted by debug...

Environment

No response

NuGet package version(s)

No response

Affected platforms

Build tasks

IDE

Visual Studio 2022

IDE version

17.13.6

Relevant plugins

No response

Anything else we need to know?

Added Assets/Samples/**.txt files which are containing xaml copyed code, which are throwing an Issue when used as UnoAsset available as BuildAction, but not documented? set them to Resources but dont know if thats the correct setting when I want to load them with IStorage at runtime and this could cause this issue also

[DevTKSS]

Dont know what exactly that is sourcing in but at current last stable of this repo (parent of "delete SampleCode" commit) its not showing it. But the styles are not theme responsive which makes the resourced DataTemplates not really pretty...

[jeromelaban]

This is an odd error. As it's a WinAppSDK error, the only way around it is to find a workaround, there's generally no fix that we can make in Uno that can help.

[DevTKSS]

Hm since the theme taken from the material toolkit is not theme responsive, can you tell if you might see the reason for this when its set to desktop and not Windows target? All I could consider is just not name any styles and so on but thats nor really cool as you will know... Maybe I did oversee something? 😅

[DevTKSS]

@jeromelaban I tryed that days to re-activate the windows target on the app as I only dragged the target out of the TargetFrameworks and commented it out... Still not building to windows target with 6.0.146 🤔 I dont have any idea whats causing this...

do you maybe have any known workaround I could use for unsing a ResourceDictionary through the Material Toolkit provided MergedDictionarys in my App.xaml? Readed from one of the MS MVP on our discord server that he knowing the page resources as more unreliable and preferres the app approach... Will see if I find the name to link him, maybe he has a idea for this...

[DevTKSS]

@AndrewKeepCoding Do you have any idea why this is happening or how I could make this project build also properly to windows but using a central ResourceDictionary for DataTemplates?

Linking to the src directory of the app I tested it last days on to include again...

https://github.com/DevTKSS/DevTKSS.Uno.SampleApps/tree/master/src%2FDevTKSS.Uno.Samples.MvuxGallery

To Desktop target thats not problem at all, but as soon as its to windows target, no chance...

[AndrewKeepCoding]

@DevTKSS x:Bind or x:DataType requires a code-behind cs file. Something like this:

Styles/Generic.xaml.cs

namespace DevTKSS.Uno.Samples.MvuxGallery.Styles;

public partial class Generic : ResourceDictionary
{
    public Generic()
    {
        InitializeComponent();
    }
}

Styles/Generic.xaml

<ResourceDictionary x:Name="MyStyleTemplates"
    x:Class="DevTKSS.Uno.Samples.MvuxGallery.Styles.Generic"
    ....

microsoft/microsoft-ui-xaml#10571

It might be worth considering a different file (class) name, ThemeResources.xaml/ThemeResources.xaml.cs maybe?

That said, now you'll get the following exception:

The text associated with this error code could not be found.
Cannot find a Resource with the Name/Key DefaultPersonPictureStyle [Line: 82 Position: 17]

Adding the XamlControlsResources in Generic.xaml doesn't help.

<ResourceDictionary.MergedDictionaries>
    <XamlControlsResources xmlns="using:Microsoft.UI.Xaml.Controls" />
</ResourceDictionary.MergedDictionaries>

I'm still not sure if this comes from Uno or WinUI. Removing that line fixes the issue, though it seems that you don't need the default style there.

[DevTKSS]

@AndrewKeepCoding that's for checking on this! Indeed I think as I were creating this ResourcesDictionary file, I used the uno docs guide for defining own template librarys🤔 will check on the advised name there and if that name is indeed advised like this there I will make a quick PR to fix this doc, so others will not stumble over this in the future and not knowing why thats happening 😅

To the Codebehind and this also in my case applies to the Control templates aka CustomControl/UserControl:

I think Jeromé told me in the past on discord server that there is kind of a limitation for this in mvux apps😅
if I remember correctly, this requires to do it in an mvvm approach (=>which could potentially cause problems if used alongside with mvvm feature) and trying it although to do it in mvux did cause already problems in the same app spoken of, in one of the first commits, when I tryed to define and use a CustomControl for the "GridListViewHeader" i think I did name it, which I did bind or targeted to bind to the mvux:FeedView using a mvux generated Command. Lastly the hot Reload had problems updating changes in there.

@jeromelaban I would not remember reded this remark to CustomControl -mvux vs. Mvvm on the Docs. Could this information, including a simple but usable workaround advose, get considered to be added by someone of maybe the team or any deeper involved and knowing person to the appropriate docs until this might be resolved in the future?

Additionaly reason for me trying to add such CustomControl:

Setting all the callbacks up for enabling disabling and so on were adding so much boilerplate that I also requested a enhancement to get a HeaderTemplate that could be added to ListView AND Gridview as both of them are inheriting in uno from the ListViewBase I think that was called. Its in the contributing>internals docs.
So by that we could already bind to the FeedView that could include already the refresh bound or re-use this template for both view kinds😅 added a feature request at January I think but so far, seems like nobody had time to even take a look on this to consider.
Therefore my only way to workaround this were using DataTemplates with AncestorBinding or Binding with Parent in-between.

[AndrewKeepCoding]

@DevTKSS The naming suggestion is just a tip for better naming. I don't believe it's the root of the issue here.

[DevTKSS]

@Jen-Uno maybe the external linked DataTemplate issue should get added to the external follow up Microsoft epic pinned issues list?