How to make two independent instance of a ControlTemplate In a window? - binding

Question

i have a controltemplate with a textbox and a button,the button open a sub form to select something and show selected item in the textbox,like this:
<Window.Resources>
<ControlTemplate x:Key="CreateParam">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="1*"/>
<ColumnDefinition Width="1*"/>
<ColumnDefinition Width="3*"/>
</Grid.ColumnDefinitions>
<Button Content="select" Command="{Binding ShowSpecItemViewommand}" Grid.Column="0" Margin="2"/>
<TextBox Margin="2" Text="{Binding Param}" Grid.Row="0" Grid.Column="1"/>
<TextBlock Margin="5" Text="patameter" Grid.Row="0" Grid.Column="2"/>
</Grid>
</ControlTemplate>
</Window.Resources>
and i have a property in the viewmodel like this:
public string param;
public string Param
{
get
{
return param;
}
set
{
param = value;
RaisePropertyChanged("Param");
}
}
and now i want to create two independent instance of that control in a window,but when i select a value for the first instance,both of them have been changed.should i define two property?and how can i bind them to the control template?
i'm not sure that every one can understand what i mean,so i hope someone edit my question:)

Answer 1

How do you use the Control Template? To which Control do you attach this template? Is it a template for a custom control you have? Is it a template to a known control?
How do you instantiate the DataContext for the Control Template?
While you can implement what you want using ControlTemplate (and a custom control), and if you have many (i.e. much more than two, and all over) instances of your object a ControlTemplate may be the right paradigm, you'll be way better off using DataTemplate, or UserControl. There is more than one way to achieve what you want, but the code below is considered the "canonical" solution:
Say Param is a property of MyVM object. Then your XAML file should be:
<Window
x:Class="SO.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:so="clr-namespace:SO"
Height="200" Width="350"
Title="SO Sample"
>
<Window.Resources>
<DataTemplate DataType="{x:Type so:MyVM}">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="1*"/>
<ColumnDefinition Width="1*"/>
<ColumnDefinition Width="3*"/>
</Grid.ColumnDefinitions>
<Button Content="select" Command="{Binding ShowSpecItemViewommand}" Grid.Column="0" Margin="2"/>
<TextBox Margin="2" Text="{Binding Param}" Grid.Row="0" Grid.Column="1"/>
<TextBlock Margin="5" Text="patameter" Grid.Row="0" Grid.Column="2"/>
</Grid>
</DataTemplate>
</Window.Resources>
<StackPanel>
<ContentControl>
<so:MyVM Param="1234" />
</ContentControl>
<ContentControl>
<so:MyVM Param="5678" />
</ContentControl>
</StackPanel>
</Window>