CODEWITHSUNDEEP
c#wpfxamlmvvm
juergen d
juergen d

Reputation: 204746

Bind Textbox in UserControl

My View

<UserControl x:Class="Views.PartView"
             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:viewModels="clr-namespace:EComponents.ViewModels"
             mc:Ignorable="d" 
             x:Name="PartUc"
             d:DataContext="{d:DesignInstance viewModels:PartViewModel}">        
        <Grid>
            <TextBox x:Name="NameTb" Text="{Binding Name}" />
       </Grid>
</UserControl>

My ViewModel

public class PartViewModel : ViewModel<Part>
{
    public PartViewModel(Part model) : base(model)
    {
        PartListViewModel.OnSelectedPartChanged += PartListViewModel_OnSelectedPartChanged;
    }    
    void PartListViewModel_OnSelectedPartChanged(Part p)
    {
        Model = Part.GetPart(p);
    }      
    public string Name
    {
        get
        {
            return Model.Name;
        }
        set
        {
            if (Name != value)
            {
                Model.Name = value;
                this.OnPropertyChanged("Name");
            }
        }
    }   
}

My Model

public class Part
{
    public string Name { get; set; }
}

I don't know why but the TextBox in my UserControl does not get filled with the Name property of my part even though this line is called

Model = Part.GetPart(p);

I set the DataContent of my View like this

public partial class PartView : UserControl
{
    public PartView()
    {
        InitializeComponent();
        DataContext = new PartViewModel(new Part());
    }
}

Upvotes: 0

Views: 95

Answers (2)

dkozl
dkozl

Reputation: 33364

Is seems as if you don't notify UI when Model is changed in PartListViewModel_OnSelectedPartChanged. You need to call this.OnPropertyChanged(...) for every Model related property after it's changed or call it with null argument this.OnPropertyChanged(null) to refresh all properties

void PartListViewModel_OnSelectedPartChanged(Part p)
{
    Model = Part.GetPart(p);
    this.OnPropertyChanged(null);
}

Upvotes: 2

Brian Driscoll
Brian Driscoll

Reputation: 19635

You have a slight issue in your code:

        if (Name != value)
        {
            Model.Name = value;
            this.OnPropertyChanged("Name");
        }

Should be:

        if (Model.Name != value)
        {
            Model.Name = value;
            this.OnPropertyChanged("Name");
        }

Self-referencing the Name property of your view model will give you issues.

Last but not least you need code in your code-behind to bind the DataContext at runtime.

Edit

I just took a look at your code again as well as the comments on the question. When you set the value of Model in the event handler, you need to set DataContext there as well. Changing the model reference doesn't update the DataContext.

Upvotes: 0

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