Passing value from bound ViewModel to UserControl

Question

I am trying to create a conditional textbox usercontrol on which there will be a property that accepts

Condition (true|false, Binding)
FalseValue (true|false, Binding, StaticResource)
TrueValue (true|false, Binding, StaticResource)

The problem is my StaticResource and literal value is working good except for the binding.

<Grid Background="#FFBDBDBD" Margin="0,154,0,266">
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="100*"></ColumnDefinition>
    </Grid.ColumnDefinitions>
    <Grid.RowDefinitions>
        <RowDefinition Height="33*"></RowDefinition>
        <RowDefinition Height="33*"></RowDefinition>
        <RowDefinition Height="33*"></RowDefinition>
    </Grid.RowDefinitions>
    <userControls:ConditionalTextBox 
        Grid.Column="0"
        Grid.Row="0"
        Condition="{Binding Path=IsTrue, Mode=TwoWay}"
        FalseValue="{StaticResource FalseValRes}" 
        TrueValue="{StaticResource TrueValRes}" 
        HorizontalAlignment="Left" Width="500">
    </userControls:ConditionalTextBox>

    <userControls:ConditionalTextBox 
        Grid.Column="0"
        Grid.Row="1"
        Condition="True"
        FalseValue="{Binding FalseValueDefined}" 
        TrueValue="{Binding TrueValueDefined}" 
        HorizontalAlignment="Left" Width="500">
    </userControls:ConditionalTextBox>

    <userControls:ConditionalTextBox 
        Grid.Column="0"
        Grid.Row="2"
        Condition="False"
        FalseValue="False Value (string)" 
        TrueValue="True Value (string)" 
        HorizontalAlignment="Left" Width="500">
    </userControls:ConditionalTextBox>
</Grid>

with code behind

public sealed partial class MainPage : Page
    {
        public MainPage()
        {
            this.InitializeComponent();

            this.DataContext = new VMTest
            {
                IsTrue = true,
                FalseValueDefined = "False Value (Binding)",
                TrueValueDefined = "True Value (Binding)"
            };
        }
    }

and this VM

public class VMTest : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;


        private bool isTrue;
        public bool IsTrue
        {
            get { return isTrue; }
            set
            {
                isTrue = value;
                if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs("IsTrue"));
            }
        }

        private string trueValueDefined;
        public string TrueValueDefined
        {
            get { return trueValueDefined; }
            set
            {
                trueValueDefined = value;
                if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs("TrueValueDefined"));
            }
        }

        public string falseValueDefined;
        public string FalseValueDefined
        {
            get { return falseValueDefined; }
            set
            {
                falseValueDefined = value;
                if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs("FalseValueDefined"));
            }
        }
    }

as the result, StaticResource and literal value reached successfully to UserControl and maybe i missed something on bindings that it wont affect

Result

Any help would be appreciated.

TIA

FishySwede FishySwede · Accepted Answer · 2016-03-21T07:03:11

I would start by looking at the datacontext resolution. Have you tried, just to make sure the datacontext is correct:

<userControls:ConditionalTextBox 
    x:Name="boundControl"
    Grid.Column="0"
    Grid.Row="1"
    Condition="True"
    FalseValue="{Binding FalseValueDefined}" 
    TrueValue="{Binding TrueValueDefined}" 
    HorizontalAlignment="Left" Width="500">
</userControls:ConditionalTextBox>

and

public sealed partial class MainPage : Page
{
    public MainPage()
    {
        this.InitializeComponent();

        this.boundControl.DataContext = new VMTest
        {
            IsTrue = true,
            FalseValueDefined = "False Value (Binding)",
            TrueValueDefined = "True Value (Binding)"
        };
    }
}

It might also be helpful to examine the binding trace information. Try

 "{Binding FalseValueDefined, PresentationTraceSources.TraceLevel=High}"

If you run your program and look at the visual studio debug output, you will get some debug rows describing WPF's attempts to resolve the binding.

Passing value from bound ViewModel to UserControl

1 Answers