使用绑定MVVM填充文本框
问题描述:
我试图弄清楚MVVM是如何工作的,并希望从简单开始。使用绑定MVVM填充文本框
我做了一个Model,一个View和一个ViewModel。我把视线连接到一个窗口。这或多或少起作用。 在视图中,我有一个文本框,我想填写一个属性的值。文本框保持空白!?
这是我有: 型号:
namespace Qbox_0001.Model
{
public class RegistratieModel
{
}
public class Registratie : INotifyPropertyChanged
{
//Fields
private string programmaNaam;
//eventhandler die kijkt of een property wijzigt
public event PropertyChangedEventHandler PropertyChanged;
private void RaisePropertyChanged(string property)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(property));
}
}
//Properies
public string ProgrammaNaam
{
get { return programmaNaam; }
set
{
if (programmaNaam != value)
{
programmaNaam = value;
RaisePropertyChanged("ProgrammaNaam");
}
}
}
}
}
的观点:
<UserControl x:Name="UserControlRegistratie" x:Class="Qbox_0001.Views.RegistratieView"
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:Qbox_0001.Views"
mc:Ignorable="d" Height="1000" Width="860" MaxWidth="860" HorizontalContentAlignment="Left" VerticalContentAlignment="Top">
<Grid x:Name="GridRegistratie">
<Grid.RowDefinitions>
<RowDefinition x:Name="RowDef_Menu" Height="21*" MaxHeight="21" MinHeight="21"/>
<RowDefinition x:Name="RowDef_TabControl" Height="500*" MinHeight="500"/>
<RowDefinition x:Name="Rowdef_Bottom" Height="40*" MaxHeight="40" MinHeight="40"/>
</Grid.RowDefinitions>
<Grid x:Name="Grid_Registratie_WorkArea" Grid.Row="1">
<TabControl x:Name="TabControl_Registratie">
<TabItem Header="Registratie">
<Grid x:Name="Grid_Tab_Registratie">
<Border>
<Grid>
<Grid.RowDefinitions>
<RowDefinition x:Name="GridRowDef_Algemeen" MinHeight="68" Height="68*" MaxHeight="68"/>
<RowDefinition x:Name="GridRowDef_Locatie" MinHeight="120" Height="120*" MaxHeight="120"/>
<RowDefinition x:Name="GridRowDef_AantalDagen" MinHeight="105" Height="105*" MaxHeight="105"/>
<RowDefinition x:Name="GridRowDef_MaxDagen" MinHeight="105" Height="105*" MaxHeight="105"/>
<RowDefinition x:Name="GridRowDef_Lokaal" MinHeight="100" Height="100*" MaxHeight="100"/>
<RowDefinition x:Name="GridRowDef_LicBestand" Height="150*" MaxHeight="150" MinHeight="150"/>
</Grid.RowDefinitions>
<GroupBox x:Name="GroupBox_algemeen" Header="Algemeen" Margin="10,4,10,3">
<Grid>
<Label x:Name="Label_Klant" Content="Klant:" HorizontalAlignment="Left" Margin="10,10,0,0" VerticalAlignment="Top" Padding="0,5,5,5"/>
<Label x:Name="Label_Programma" Content="Programma:" HorizontalAlignment="Left" Margin="356,10,0,0" VerticalAlignment="Top"/>
<Label x:Name="Label_Versie" Content="Versie:" HorizontalAlignment="Left" Margin="645,10,0,0" VerticalAlignment="Top"/>
<TextBox x:Name="textBox_KlantNaam" HorizontalAlignment="Left" Height="23" Margin="49,10,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="288"/>
<!-- the textbox keeps empty -->
<TextBox x:Name="TextBox_ProgrammaNaam" Text="{Binding ElementName=RegistratieViewModel, Path=ProgrammaNaam, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" HorizontalAlignment="Left" Height="23" Margin="431,10,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="190" IsEnabled="False" />
<TextBox x:Name="TextBox_Versie" HorizontalAlignment="Left" Height="23" Margin="695,10,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="120" IsEnabled="False" />
</Grid>
</GroupBox>
</Grid>
</Border>
</Grid>
</TabItem>
<TabItem Header="Licentie(s)">
<Grid x:Name="Grid_Tab_Licentie" Background="#FFE5E5E5"/>
</TabItem>
</TabControl>
</Grid>
</Grid>
</UserControl>
在View.cs:
namespace Qbox_0001.Views
{
/// <summary>
/// Interaction logic for RegistratieView.xaml
/// </summary>
public partial class RegistratieView : UserControl
{
public RegistratieView()
{
InitializeComponent();
this.DataContext = new Qbox_0001.ViewModel.RegistratieViewModel();
}
}
}
视图模型
using Qbox_0001.Model; //
using System.Collections.ObjectModel; //
namespace Qbox_0001.ViewModel
{
public class RegistratieViewModel
{
public RegistratieViewModel()
{
loadRegistratieOnderdelen();
}
public ObservableCollection<Registratie> RegistratieOnderdelen //Registratie = "public class Registratie : INotifyPropertyChanged" van de Model
{
get;
set;
}
public void loadRegistratieOnderdelen()
{
ObservableCollection<Registratie> regOnderdelen = new ObservableCollection<Registratie>();
regOnderdelen.Add(new Registratie { ProgrammaNaam = "Test" });
}
}
}
答
我可以看到你的代码有几个问题。
您正在使用数据填充本地ObservableCollection(在您的loadRegistratieOnderdelen()方法中),但由于其本地,它不是DataContext的成员,因此无法用于View。您必须使用公开属性,例如RegistratieOnderdelen,您已在RegistratieViewModel中声明了该属性。
接下来,您正在使用ObservableCollection,而您可能只是想使用String类型的属性。当您想要表示列表时使用集合,例如在ListView或ItemsControl中。您的视图表明您想要绑定单个文本值,因此String类型的公共属性更有意义。
最佳,尼科
答
DataContext
的是RegistratieViewModel
。该类有一个RegistratieOnderdelen
属性,该属性返回Registratie
对象的集合。
你可以绑定到一个这样的项目的ProgrammaNaam
财产,但你需要指定要绑定到的项目,例如第一个:
<TextBox x:Name="TextBox_ProgrammaNaam" Text="{Binding Path=RegistratieOnderdelen[0].ProgrammaNaam, UpdateSourceTrigger=PropertyChanged}" ... />
是有一个很好的教程初学者吗? – Hansvb
@Hansvb去看Rachel Lim的博客。为初学者详细解释并提供简单的示例。 https://rachel53461.wordpress.com/ – Bojje