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POHow to reuse a UserControl in situations where the DataContext is slightly different?
 

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  1. POHow to reuse a UserControl in situations where the DataContext is slightly different?
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    <p>This is my first post on StackOverflow and also my first Question. I had created a UserControl in WPF with the MVVM Pattern (called Block). This UserControl should be used in another UserControl, as DataTemplate of a ListBox (called Sector).</p> <p>The Block Control should be used as standalone and as DataTemplate for different UserControls.</p> <p>If I set the DataContext in the View of Block, the standalone Version works great, but not as part of the Sector View.</p> <p>If I don´t set the DataContext in the View of Block, it works in Sector but don’t standalone.</p> <p>My question is, is it the only way to leave the DataContext in the View of Block and set it in the View I used the Control or the ViewModel?</p> <p>Here is my Code:</p> <p><strong>Model of Block:</strong></p> <pre><code>public class BlockModel : ModelBase { #region private Variables string blockName = "Block"; string blockContent = "00000"; #endregion private Variables #region Properties public string BlockName { get { return blockName; } set { blockName = value; NotifyPropertyChange("BlockName "); } } public string BlockContent { get { return blockContent; } set { blockContent = value; NotifyPropertyChange("BlockContent"); } } #endregion Properties #region ctor public BlockModel () { } #endregion ctor } </code></pre> <p><strong>ViewModel of Block:</strong></p> <pre><code>public class BlockViewModel : ViewModelBase { #region private Variables string charToFill = "0"; DelegateCommand fillWithChar; BlockModel dataModel = new BlockModel(); #endregion private Variables #region Properties public Models. BlockModel DataModel { get { return dataModel; } set { dataModel = value; } } public string BlockContent { get { return dataModel. BlockContent; } set { if (dataModel. BlockContent != value) { dataModel. BlockContent = value; NotifyPropertyChange ("BlockContent"); } } } public string BlockName { get { return dataModel. BlockName; } set { if (dataModel. BlockName != value) { dataModel. BlockName = value; NotifyPropertyChange("BlockName"); } } } public string CharToFill { get { return charToFill; } set { if (charToFill != value) { charToFill = value; NotifyPropertyChange ("CharToFill"); } } } public ICommand FillWithChar { get { if (fillWithChar == null) fillWithChar = new DelegateCommand(FillText); return fillWithChar; } } #endregion Properties #region ctor public BlockViewModel() { } #endregion ctor #region Methods private void FillText() { CodingBlockContent = CodingBlockContent.PadLeft(32, charToFill[0]); } #endregion Methods </code></pre> <p>}</p> <p><strong>View of Block:</strong></p> <pre><code>&lt;UserControl x:Class="…./Block" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:local="clr-namespace:…/Controls" mc:Ignorable="d" d:DesignWidth="460" d:DesignHeight="44"&gt; &lt;Grid&gt; &lt;Grid.ColumnDefinitions&gt; &lt;ColumnDefinition Width="124" /&gt; &lt;ColumnDefinition Width="301" /&gt; &lt;ColumnDefinition Width="30"/&gt; &lt;ColumnDefinition/&gt; &lt;/Grid.ColumnDefinitions&gt; &lt;Grid.RowDefinitions&gt; &lt;RowDefinition Height="30"&gt;&lt;/RowDefinition&gt; &lt;/Grid.RowDefinitions&gt; &lt;TextBlock Grid.Row="0" Grid.Column="0" Text="{Binding BlockName}" HorizontalAlignment="Left" VerticalAlignment="Center" FontSize="14" Margin="2,6"/&gt; &lt;ComboBox FontFamily="Consolas" Grid.Row="00" Grid.Column="1" Text="{Binding BlockContent, Mode=TwoWay}" Tag="{Binding BlockName}" Name="cbxBlock" FontSize="14" HorizontalAlignment="Left" VerticalAlignment="Center" Width="290" Margin="1,4,0,5" IsEditable="True" Height="26"&gt; &lt;ComboBoxItem Content=""&gt;&lt;/ComboBoxItem&gt; &lt;ComboBoxItem Content="0000000000000"&gt;&lt;/ComboBoxItem&gt; &lt;StackPanel HorizontalAlignment="Left" VerticalAlignment="Top" Orientation="Horizontal"&gt; &lt;TextBox Margin="10,2,0,2" Text="0" Width="24" FontSize="14" Name="tbxChar" MaxLength="1"&gt;&lt;/TextBox&gt; &lt;TextBlock Margin="10,2,0,2" Text="auffüllen" VerticalAlignment="Center" FontSize="14"&gt;&lt;/TextBlock&gt; &lt;Button Margin="10,2,0,2" Content="Ausführen" Width="100" Command="{Binding FillWithChar}"&gt;&lt;/Button&gt; &lt;/StackPanel&gt; &lt;/ComboBox&gt; &lt;TextBlock Grid.Row="0" Width="30" Grid.Column="2" Text="{Binding CodingBlockContent.Length}" HorizontalAlignment="Left" VerticalAlignment="Center" FontSize="14" Margin="2,6,0,6" Grid.ColumnSpan="2"/&gt; &lt;/Grid&gt; </code></pre> <p></p> <p><strong>Model of Sector:</strong></p> <pre><code>public class SectorModel { #region private Variables int blockAmount = 4; string sectorNumber = "Sektor"; int blockBegin = 0; bool isSectorInUse = false; #endregion private Variables #region Properties public string SectorNumber { get { return sectorNumber; } set { sectorNumber = value;} } public int BlockBegin { get { return blockBegin; } set { blockBegin = value; } } public bool IsSectorInUse { get { return isSectorInUse; } set { isSectorInUse = value;} } public int BlockAmount { get { return blockAmount; } set { blockAmount = value;; } } #endregion Properties public SectorModel() { } } </code></pre> <p><strong>ViewModel of Sector:</strong></p> <pre><code>public class SectorViewModel : ViewModelBase { #region private Variables SectorModel dataModel = new SectorModel(); ObservableCollection&lt;BlockViewModel&gt; sectorBlocks = new ObservableCollection&lt;BlockViewModel&gt;(); #endregion private Variables #region Properties public SectorModel DataModel { get { return dataModel; } set { dataModel = value; } } public ObservableCollection&lt;BlockViewModel&gt; SectorBlocks { get { return sectorBlocks; } set { sectorBlocks = value; NotifyPropertyChange ("SectorBlocks"); } } public string SectorNumber { get { return "Sektor " + DataModel.SectorNumber; } set { DataModel.SectorNumber = value; NotifyPropertyChange ("SectorNumber"); } } public int BlockBegin { get { return DataModel.BlockBegin; } set { DataModel.BlockBegin = value; SetBlocks(); OnPropertyChanged("BlockBegin"); } } public bool IsSectorInUse { get { return DataModel.IsSectorInUse; } set { DataModel.IsSectorInUse = value; NotifyPropertyChange ("IsSectorInUse"); } } public int BlockAmount { get { return DataModel.BlockAmount; } set { DataModel.BlockAmount = value; SetBlocks(); NotifyPropertyChange ("CodingBlockAmount"); } } #endregion Properties void SetBlocks() { while (SectorBlocks.Count != BlockAmount) { SectorBlocks.Add(new BlockViewModel()); } int begin = BlockBegin; foreach (BlockViewModel block in SectorBlocks) { block.CodingBlockName = "Block " + begin.ToString().PadLeft(2, '0'); block++; } } public SectorViewModel() { SetBlocks(); } } </code></pre> <p><strong>View of Sector:</strong></p> <pre><code>&lt;UserControl xmlns:Views="clr-namespace:…/RFIDControls" x:Class="…/Sector" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" mc:Ignorable="d" d:DesignHeight="300" d:DesignWidth="473"&gt; &lt;Border BorderBrush="Black" BorderThickness="0,0,0,1"&gt; &lt;Expander Name="expMain" Margin="0,0,4,0"&gt; &lt;Expander.Header&gt; &lt;Grid Name="grdHeader"&gt; &lt;Grid.ColumnDefinitions&gt; &lt;ColumnDefinition Width="100" /&gt; &lt;ColumnDefinition Width="300" /&gt; &lt;ColumnDefinition Width="30" /&gt; &lt;/Grid.ColumnDefinitions&gt; &lt;TextBlock Grid.Column="0" Grid.Row="0" Height="24" Text="{Binding SectorNumber}" HorizontalAlignment="Left" VerticalAlignment="Center" FontSize="14" FontWeight="Bold" Panel.ZIndex="98"/&gt; &lt;CheckBox Grid.Column="2" VerticalAlignment="Center" IsChecked="{Binding IsSectorInUse}"&gt;&lt;/CheckBox&gt; &lt;/Grid&gt; &lt;/Expander.Header&gt; &lt;Grid&gt; &lt;ListBox ItemsSource="{Binding SectorBlocks}" Name="listBox"&gt; &lt;ListBox.ItemTemplate&gt; &lt;DataTemplate DataType="{x:Type Views:BlockViewModel}"&gt; &lt;Views:Block/&gt; &lt;/DataTemplate&gt; &lt;/ListBox.ItemTemplate&gt; &lt;/ListBox&gt; &lt;/Grid&gt; &lt;/Expander&gt; &lt;/Border&gt; </code></pre> <p></p> <p>Thank you.</p> <p>With kind regards from Germany</p> <p>Dominik</p> <p>PS: I hope my English is not so bad as I suppose</p>
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    1. COThat's weird. Can you try something out. Do this in the DataTemplate of the SectorView <Views:Block DataContext="{Binding}"/>
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    2. COWhat do you mean by standalone? Should it be bound to a single instance of BlockViewModel which is inside SectorViewModel?
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    3. COThank you for your fast response. I tried <Views:Block DataContext="{Binding} this, but same issue here. With standalone i mean that this Control will be work alnoe in a different Window. I don´t want to set the Datacontext in there too. I want to set the DataContext in die Control itself, so there is no need to set it in other cirumstances.
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