问题
Admittedly I am new to wpf. But i have spent some time Googling about it all and I am stumped.
in essence i want to update my TextBlock in my UI using Binding whenever my Model values change.
So this is my Model:
using System.ComponentModel;
using System.Runtime.CompilerServices;
namespace WpfApplication1
{
public class MyModel : INotifyPropertyChanged
{
protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
public event PropertyChangedEventHandler PropertyChanged;
protected bool SetProperty<T>(ref T storage, T value, [CallerMemberName] string propertyName = null)
{
if (Equals(storage, value))
{
return false;
}
storage = value;
this.OnPropertyChanged(propertyName);
return true;
}
public string MyField { get; set ; }
}
}
This is my UI:
<Window x:Class="WpfApplication1.MainWindow"
xmlns:viewModels="clr-namespace:WpfApplication1"
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"
xmlns:local="clr-namespace:WpfApplication1"
d:DataContext="{d:DesignInstance viewModels:MyModel, IsDesignTimeCreatable=True}"
mc:Ignorable="d"
Title="MainWindow" Height="350" Width="525">
<Window.DataContext>
<viewModels:MyModel></viewModels:MyModel>
</Window.DataContext>
<Grid>
<StackPanel Orientation="Vertical">
<TextBlock Text="{Binding MyModel.MyField}"></TextBlock>
<Button Content="Click Me!" Click="Button_Click" />
</StackPanel>
</Grid>
</Window>
This is my code behind:
using System.Windows;
namespace WpfApplication1
{
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
public MyModel myModel = new MyModel();
private void Button_Click(object sender, RoutedEventArgs e)
{
myModel.MyField = "has worked";
}
}
}
When i press the button the text does not change on the UI..?
回答1:
The instance you create in the code behind is not the same as you assign in xaml.
Change the button click event to
private void Button_Click(object sender, RoutedEventArgs e)
{
var model = this.DataContext as MyModel;
model.MyField = "has worked";
}
And the binding in xaml to
<TextBlock Text="{Binding MyField}"></TextBlock>
And in your viewmodel you are not calling the notify property changed. So create a private field and modify the property as below.
private string myField;
public string MyField
{
get { return this.myField; }
set { this.SetProperty(ref this.myField, value); }
}
来源:https://stackoverflow.com/questions/34655674/my-property-does-not-update-using-callermembername