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Changing property IsIndeterminate on MaterialDesign button in WPF

I'm using a material design button in WPF and I'm not quite sure how to control the property IsIndeterminate from within C# code as the below does not work, like it usually does with "standard" properties like Content etc.
BTN_Search.materialDesign:ButtonProgressAssist.IsIndeterminate = true;
The WPF for the button below:
<Grid Width="124" Margin="5" VerticalAlignment="Center">
<Button Style="{StaticResource MaterialDesignRaisedButton}"
materialDesign:ButtonProgressAssist.Value="-1"
materialDesign:ButtonProgressAssist.IsIndicatorVisible="True"
materialDesign:ButtonProgressAssist.IsIndeterminate="False"
Content="Search"
Margin="2,0"
IsEnabled="{Binding DataContext.ControlsEnabled, RelativeSource={RelativeSource FindAncestor, AncestorType=Window}}"
x:Name="BTN_Search"
Click="Search_Click"/>
</Grid>
I want the materialDesign:ButtonProgressAssist.IsIndeterminate property to be changed in the Click event when the button is pressed and then once I am done processing I need to change it back to False.

It is a dependency property so it can be set like this:
ButtonProgressAssist.SetIsIndeterminate(BTN_Search, true);
There is other examples on Github in the MaterialDesignInXamlTooking project https://github.com/MaterialDesignInXAML/MaterialDesignInXamlToolkit/blob/master/MaterialDesignThemes.Wpf.Tests/ButtonProgressAssistTests.cs

UWP ButtonColumn MvvmLight / Telerik / WindowsTemplate Studio

I´m trying to add a ButtonColumn to a TelerikDataGrid which was generated by the Windows Template Studio, without CodeBehind.
In a perfect world it would work like this, I think.
<tg:DataGridTemplateColumn x:Uid="Table_Open" >
<tg:DataGridTemplateColumn.CellContentTemplate >
<DataTemplate>
<Button x:Uid="Button_Open" Command="{x:Bind ViewModel.OpenCustomerCommand}"></Button>
</DataTemplate>
</tg:DataGridTemplateColumn.CellContentTemplate>
</tg:DataGridTemplateColumn>
This doesn't work, now I tried many opportunities but never reach the ViewModel.
I know in WPF it would work using
RelativeSource={RelativeSource AncestorType={x:Type UserControl},
But I don't get it reproduced in my UWP case.

I'm afraid you can't use x:bind to bind OpenCustomerCommand in DataTemplate, In general, if we want to bind viewmodel's OpenCustomerCommand we need set current Page DataContext as ViewModel then use binding markup extension to bind like the following.
<Button HorizontalAlignment="Right"
Margin="0,0,30,0"
Content="Favorite"
Command="{Binding ElementName=RootGrid,Path=DataContext.OpenCustomerCommand }"
/>
And this is the similar case that your could refer.

Click handler of button in datatemplate not working

I have a resource dictionary combining a number of datatemplates. I'm including this resource dictionary as a ResourceDictionary.MergedDictionaries in my Page.Resources. One of my datatemplates is a ListView and while the item source and item click is working correctly, a separate button on the ListViewItem, set in the datatemplate, is not calling my click method. Im unsure about setting this up correctly.
This click method is defined in the code behind class the defines the pages Xaml including the resource dictionary and using my datatemplate for ListViewItems.
Dictionaries
DataTemplates.xaml <- ListView template here with a button click defined in the page cs, i.e. Click="MyPages_ClickMethod"
Pages
MyPage.xaml
MyPage.xaml.cs <- click method defined here, MyPages_ClickMethod()
Here is how I am setting up the button in the datatemplate:
<Button Tag="{Binding id}" Click="MultiShareSelectFileButton_Click" Background="Transparent" Visibility="{Binding multiShareSelected, Converter={StaticResource BooleanToVisibilityConverter}, ConverterParameter=Inverted, Mode=OneWay}">
<Image Width="27" Source="ms-appx:///Assets/sharePlusIcon#2x.png" VerticalAlignment="Center" HorizontalAlignment="Center">
</Image>
</Button>
Is it possible to do this without using ICommand?
Something like: Click="{x:Bind Path=pages:ProductPage.MultiShareSelectFileButton_Click}", but this is complaining that MultiShareSelectFileButton_Click should be static

I'll get right to it. Here is the issue,
Your DataTemplate is in a resource dictionary. The resource dictionary is made for styles and converters if I may. Putting the DataTemplate in a resource dictionary is not recommended.
Why isn't it recommended?
The reason is straight, resource dictionaries are used to put global data. For ex: a control style that you might want to be available through out your app or your converters which are being used frequently.
This is because generally you would define the resource dictionary in your app.xaml which runs when your splashscreen appears.
Now if you have a lot of stuff (DataTemplates, Styles, Converters) all defined into resource dictionaries that are merged in <Application.ResourceDictionary> part of app.xaml, it's gonna have a significant impact on your app launch time, which will spoil your user's experience.
What's advised?
It's advised to keep your converters and styles not global unless you need them everywhere. For example: If you have a BoolToVisibilityConverter or a CustomRoundButtonStyle which you use only on one page/userControl out of 4. Then it doesn't make sense to load the style or converter for the other 3 Pages. So you should declare them in <Page.Resources> instead.
Same for your DataTemplate why declare it globally if you want to use it just once. Rather declare it to your <Page.Resources>. Your problem will be solved immediately as your Page will have a code-behind, so your xaml will know where to look for the method. That's where things are going wrong.
But in-case you have a single DataTemplate to be used on all your Views below is your solution:
Your Solution:
In-case you have to use it in a resource dictionary, use {x:Bind} and x:DataType="Models:YourDataContextModel" to bind your DataTemplate to your model. this ways your xaml will know exactly where to look for the method on click.
Below is a sample of it:
<DataTemplate x:Key="HelloTemplate" x:DataType="yourDefinedNameSpace:YourModel">
<Button Click="{x:Bind GoFetchData}"/>
</DataTemplate>
Where YourModel exists in a namespace defined as "yourDefinedNameSpace" in xaml and it contains a method of signature: internal void GoFetchData()
I hope this helps. Feel free to use the comments section if you have any doubts

I found that it was also necessary to specify ClickMode="Press" in Xaml.
<Button Content="" Focusable="True" FontFamily="Segoe UI Symbol" FontSize="16" Background="{StaticResource HeroLightGray}" Foreground="Black" HorizontalAlignment="Center" VerticalAlignment="Center"
ClickMode="Press"
Command="{Binding DataContext.CopyMetadataSourceAsync, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}}}" CommandParameter="{Binding .}" />
I do not recall having to do this in the past, but after spending hours troubleshooting, converting RelayCommand to IAsyncCommand, etc. this is the only thing that worked. In fact, I couldn't even get a regular code-behind "Click event" method to fire unless I included that ClickMode="Press"!

Best practice to handle ListView ItemClick in UWP using MVVM

I need to open a new view (item details) on mouse double click in ListView in UWP using MVVM. In WPF I used a command with a parameter and EventTrigger but Microsoft does not recommended to use it in UWP:
Triggers, EventTrigger, Actions and BeginStoryboard are not commonly used. These API mainly exist for compatibility in XAML originally used for Microsoft Silverlight...For events in control templates, use visual states and VisualStateManager.
As I understood it is used when you need to change visual state of the control but I need to open a new view.
How can I use VisualStateManager for my purpose?
There is how my XAML looked in WPF:
<ListBox x:Name="PersonsListControl" Grid.RowSpan="3" Grid.Row="0" Grid.Column="2"
ItemsSource="{Binding Path=PersonsProvider}"
ItemsPanel="{StaticResource PersonsListPanelTemplate}"
ItemTemplate="{StaticResource PersonsListItemTemplate}"
SelectedItem="{Binding SelectedPerson}"
ScrollViewer.HorizontalScrollBarVisibility="Disabled">
<i:Interaction.Triggers>
<i:EventTrigger EventName="MouseDoubleClick">
<i:InvokeCommandAction
Command="{Binding GetPersonDetailsCommand}"
CommandParameter="{Binding SelectedPerson}" />
</i:EventTrigger>
</i:Interaction.Triggers>
</ListBox>

In UWP you can use {x:Bind ...} :
<ListBox ...
DoubleTapped="{x:Bind HandleDoubleTapped}" />
And in your ViewModel just create a method :
public void HandleDoubleTapped(object sender, DoubleTappedRoutedEventArgs e)
{
// your logic
}
References :
DoubleTapped
ListBox
EDIT:
#JörgenSigvardsson pointed out that x:Bind do not bind directly to the DataContext and you should create a proxy property/properties to access particular data from your page.
More on that can be read here

DataTemplate not able to resolve DataType prefix data

I'm trying to implement ListView in UWP using Window's sample code.
<ListView.GroupStyle>
<GroupStyle >
<GroupStyle.HeaderTemplate>
<DataTemplate x:DataType="data:GroupInfoList">
<TextBlock Text="{x:Bind Key}"
Style="{ThemeResource TitleTextBlockStyle}"/>
</DataTemplate>
</GroupStyle.HeaderTemplate>
</GroupStyle>
</ListView.GroupStyle>
The line -
DataTemplate x:DataType="data:GroupInfoList"
Is giving me error, shown in the left image, When creating models am I suppose to create them differently.It says
The namespace prefix "data" is not defined.
Is it a namespace that I need to include?

In your case data:GroupInfoList is the type GroupInfoList in the namespace mapping data.
You have to define the namespace mapping before you can use it.
In the Page element of SimpleListViewSample you should have something like this:
<Page
x:Class="HermantsListV2.Sample.SimpleListViewSample"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
xmlns:data="HermantsListV2.Model">
...
(Notice the xmlns:data="HermantsListV2.Model mapping.)
Just replace the namespaces in the example above with the right ones from your project and it should work.

It is a bug in the Visual Studio 2015 to solve it just comment that part of the code and run it. after that uncomment it and it will run without any error.
1- Comment this part of the code:
<!--<DataTemplate x:DataType="data:GroupInfoList">
<TextBlock Text="{x:Bind Key}"
Style="{ThemeResource TitleTextBlockStyle}"/>
</DataTemplate>-->
2- run your app.
3- uncomment this part of code:
<DataTemplate x:DataType="data:GroupInfoList">
<TextBlock Text="{x:Bind Key}"
Style="{ThemeResource TitleTextBlockStyle}"/>
</DataTemplate>
4- run the app.

I have just had the same issue, this page was copied/pasted from the Universal ListView sample.
The pasted page was full of bad characters, such as line feeds etc. I cleaned the page by removing lines and line feeds around the data template and all is fine.

I've managed to get this working sometimes if you cut the code inside your gridview etc then save, build and paste it back. Not sure why, but it fixes it sometimes, maybe VS makes something hidden there.