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Vb.net MVVM与设计时数据的绑定在设计时正常工作，但在运行时不能正常工作

vb.net mvvm

Vb.net MVVM与设计时数据的绑定在设计时正常工作，但在运行时不能正常工作,vb.net,mvvm,Vb.net,Mvvm,我有一个简单的MVVM项目，其中包含设计时数据，可以很好地处理主数据和一个列表框，每个子项都有用户控件。 但是，当我在运行时实例化这些类时，主数据会显示，而子数据不会显示（但是列表框的项目数正确，但是文本框中不会显示任何数据） 我注意到Sport上的构造函数被调用的次数远远超过我预期的次数（例如，在运行时，我预期它只被调用两次，但调用次数似乎不止这些） 我有班上的人，还有运动。每个人都可以喜欢多种运动，并拥有自己喜欢的球队。 我有一个personViewModel和sportViewModel，

我有一个简单的MVVM项目，其中包含设计时数据，可以很好地处理主数据和一个列表框，每个子项都有用户控件。 但是，当我在运行时实例化这些类时，主数据会显示，而子数据不会显示（但是列表框的项目数正确，但是文本框中不会显示任何数据）

我注意到Sport上的构造函数被调用的次数远远超过我预期的次数（例如，在运行时，我预期它只被调用两次，但调用次数似乎不止这些）

我有班上的人，还有运动。每个人都可以喜欢多种运动，并拥有自己喜欢的球队。 我有一个personViewModel和sportViewModel，它继承自viewModelBase

这是我的VB.net代码

Imports System.Collections.ObjectModel

Public Class Person
    Public Property Forename As String
    Public Property Surname As String
    Public Sports As New ObservableCollection(Of Sport)
End Class


Public Class Sport
    Public Sub New()
        Debug.WriteLine("test")
    End Sub

    Public Property SportName As String
    Public Property FavouriteProfessionalTeam As String
End Class


Imports System.Collections.ObjectModel

Namespace ViewModel

    Public Class PersonViewModel
        Inherits ViewModel.ViewModelBase

        Public Property Person1 As Person
        Public Property SportViewModels As New ObservableCollection(Of SportViewModel)

        Public Sub New()
            LoadData()
        End Sub

        ''' <summary> 
        ''' Loads the data for the application. 
        ''' </summary> 
        Private Sub LoadData()
            If IsInDesignModeStatic Then
                LoadDesignData()
            Else

            End If
        End Sub

        ''' <summary> 
        ''' Loads temporary data for use in the designer. 
        ''' </summary> 
        Private Sub LoadDesignData()
            Person1 = New Person
            Person1.Forename = "Mickey Run Time"
            Person1.Surname = "Mouse Run Time"

            Person1.Sports.Add(New Sport With {.FavouriteProfessionalTeam = "Man Utd", .SportName = "Soccer"})
            Person1.Sports.Add(New Sport With {.FavouriteProfessionalTeam = "Barcelona", .SportName = "Spanish Soccer"})
            Person1.Sports.Add(New Sport With {.FavouriteProfessionalTeam = "Ulster", .SportName = "Rugby"})

            For Each sport1 In Person1.Sports
                Dim sportVm As New SportViewModel With {.Sport1 = sport1}
                SportViewModels.Add(sportVm)
            Next

        End Sub

    End Class
End Namespace

Namespace ViewModel
    Public Class SportViewModel
        Inherits ViewModel.ViewModelBase

        Public Property Sport1 As New Sport
        Public Property Person1 As Person

        Public Sub New()
            LoadData()
        End Sub

        ''' <summary> 
        ''' Loads the data for the application. 
        ''' </summary> 
        Private Sub LoadData()
            If IsInDesignModeStatic Then
                LoadDesignData()
            Else
                ' Debug.WriteLine(Sport1.SportName)
                ' Load the student data asynchronously 
                'StudentContextInstance = New StudentContext
                'Dim loadop =
                '  StudentContextInstance.Load(StudentContextInstance.
                '             GetStudentsQuery(),
                '             AddressOf OnStudentsLoaded, Nothing)
            End If
        End Sub

        ''' <summary> 
        ''' Loads temporary data for use in the designer. 
        ''' </summary> 
        Private Sub LoadDesignData()
            Sport1 = New Sport With {.SportName = "Design Time Name", .FavouriteProfessionalTeam = "Design Time Team"}
        End Sub

    End Class
End Namespace

Imports System.ComponentModel

Namespace ViewModel

    Public Class ViewModelBase
        Implements INotifyPropertyChanged
        Public Event PropertyChanged(sender As Object, e As PropertyChangedEventArgs) Implements INotifyPropertyChanged.PropertyChanged

        Private Shared _isInDesignMode As Boolean?
        Public Shared ReadOnly Property IsInDesignModeStatic As Boolean
            Get
                If Not _IsInDesignMode.HasValue Then
                    _IsInDesignMode = DesignerProperties.GetIsInDesignMode(New DependencyObject)
                End If
                Return _IsInDesignMode.Value
            End Get
        End Property


        Protected Sub OnPropertyChanged(ByVal propertyName As String)
            ' Send an event notification that the property changed 
            ' This allows the UI to know when one of the items changes 
            If Not String.IsNullOrEmpty(propertyName) Then
                RaiseEvent PropertyChanged(Me,
                                           New PropertyChangedEventArgs(propertyName))
            End If
        End Sub



    End Class
End Namespace
这是XAML代码

<Window
    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:ViewModel="clr-namespace:WpfApplicationMVVMTest.ViewModel"
    xmlns:View="clr-namespace:WpfApplicationMVVMTest" mc:Ignorable="d" x:Class="PersonWindow"
    Title="PersonWindow" Height="1114.8" Width="542">
    <Window.Resources></Window.Resources>
    <Window.DataContext>
        <ViewModel:PersonViewModel />
    </Window.DataContext>

    <Grid>
        <Grid x:Name="Grid1" HorizontalAlignment="Left" Margin="41,39,0,0" VerticalAlignment="Top">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="Auto"/>
                <ColumnDefinition Width="Auto"/>
            </Grid.ColumnDefinitions>
            <Grid.RowDefinitions>
                <RowDefinition Height="Auto"/>
                <RowDefinition Height="Auto"/>
            </Grid.RowDefinitions>
            <Label Content="Forename:" Grid.Column="0" HorizontalAlignment="Left" Margin="3" Grid.Row="0" VerticalAlignment="Center"/>
            <TextBox x:Name="ForenameTextBox" Grid.Column="1" HorizontalAlignment="Left" Height="23" Margin="3" Grid.Row="0" Text="{Binding Person1.Forename, Mode=TwoWay, NotifyOnValidationError=true, ValidatesOnExceptions=true}" VerticalAlignment="Center" Width="120"/>
            <Label Content="Surname:" Grid.Column="0" HorizontalAlignment="Left" Margin="3" Grid.Row="1" VerticalAlignment="Center"/>
            <TextBox x:Name="SurnameTextBox" Grid.Column="1" HorizontalAlignment="Left" Height="23" Margin="3" Grid.Row="1" Text="{Binding Person1.Surname, Mode=TwoWay, NotifyOnValidationError=true, ValidatesOnExceptions=true}" VerticalAlignment="Center" Width="120"/>
        </Grid>
        <ListBox Margin="41,108,59,753" ItemsSource="{Binding Path=SportViewModels}"  >
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <View:SportUserControl DataContext="{Binding}"  Margin="5"/>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
    </Grid>
</Window>

<UserControl
             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:ViewModel="clr-namespace:WpfApplicationMVVMTest.ViewModel" x:Class="SportUserControl" 
             mc:Ignorable="d" 
             d:DesignHeight="600" d:DesignWidth="600">
    <UserControl.Resources></UserControl.Resources>
    <UserControl.DataContext>
        <ViewModel:SportViewModel />
    </UserControl.DataContext>


    <Grid>
        <Grid x:Name="Grid1" HorizontalAlignment="Left" Margin="31,26,0,0" VerticalAlignment="Top">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="Auto"/>
                <ColumnDefinition Width="Auto"/>
            </Grid.ColumnDefinitions>
            <Grid.RowDefinitions>
                <RowDefinition Height="Auto"/>
                <RowDefinition Height="Auto"/>
            </Grid.RowDefinitions>
            <Label Content="Favourite Professional Team:" Grid.Column="0" HorizontalAlignment="Left" Margin="3" Grid.Row="0" VerticalAlignment="Center"/>
            <TextBox x:Name="FavouriteProfessionalTeamTextBox" Grid.Column="1" HorizontalAlignment="Left" Height="23" Margin="3" Grid.Row="0" Text="{Binding Sport1.FavouriteProfessionalTeam, Mode=TwoWay, NotifyOnValidationError=true, ValidatesOnExceptions=true}" VerticalAlignment="Center" Width="120"/>
            <Label Content="Sport Name:" Grid.Column="0" HorizontalAlignment="Left" Margin="3" Grid.Row="1" VerticalAlignment="Center"/>
            <TextBox x:Name="SportNameTextBox" Grid.Column="1" HorizontalAlignment="Left" Height="23" Margin="3" Grid.Row="1" Text="{Binding Sport1.SportName, Mode=TwoWay, NotifyOnValidationError=true, ValidatesOnExceptions=true}" VerticalAlignment="Center" Width="120"/>
        </Grid>

    </Grid>
</UserControl>
这是我的设计时间图像，显示了3项运动（根据我的负载设计时间数据）。

这是我的运行时窗口，显示了两个运动（尽管它们没有数据，这就是问题所在）。

您正在标记和代码中设置DataContext…删除标记并坚持一种模式

非常感谢，请更全面地解释我在您的评论之后所做的事情：我在SportsView用户控件中注释了这段代码，也是为了确认这样做的副作用。SportView不再单独显示设计时数据。但是，当设计时数据显示在PersonView列表框上时，它确实会显示设计时数据。刚刚找到一种方法，这样它甚至可以用于子视图，可以使用d:DataContext，以便仅在设计时设置：d:DataContext=“{d:DesignInstance Type=vm:ViewModalThatYouWantToUse，IsDesignTimeCreatable=True}” 
<Window
    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:ViewModel="clr-namespace:WpfApplicationMVVMTest.ViewModel"
    xmlns:View="clr-namespace:WpfApplicationMVVMTest" mc:Ignorable="d" x:Class="PersonWindow"
    Title="PersonWindow" Height="1114.8" Width="542">
    <Window.Resources></Window.Resources>
    <Window.DataContext>
        <ViewModel:PersonViewModel />
    </Window.DataContext>

    <Grid>
        <Grid x:Name="Grid1" HorizontalAlignment="Left" Margin="41,39,0,0" VerticalAlignment="Top">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="Auto"/>
                <ColumnDefinition Width="Auto"/>
            </Grid.ColumnDefinitions>
            <Grid.RowDefinitions>
                <RowDefinition Height="Auto"/>
                <RowDefinition Height="Auto"/>
            </Grid.RowDefinitions>
            <Label Content="Forename:" Grid.Column="0" HorizontalAlignment="Left" Margin="3" Grid.Row="0" VerticalAlignment="Center"/>
            <TextBox x:Name="ForenameTextBox" Grid.Column="1" HorizontalAlignment="Left" Height="23" Margin="3" Grid.Row="0" Text="{Binding Person1.Forename, Mode=TwoWay, NotifyOnValidationError=true, ValidatesOnExceptions=true}" VerticalAlignment="Center" Width="120"/>
            <Label Content="Surname:" Grid.Column="0" HorizontalAlignment="Left" Margin="3" Grid.Row="1" VerticalAlignment="Center"/>
            <TextBox x:Name="SurnameTextBox" Grid.Column="1" HorizontalAlignment="Left" Height="23" Margin="3" Grid.Row="1" Text="{Binding Person1.Surname, Mode=TwoWay, NotifyOnValidationError=true, ValidatesOnExceptions=true}" VerticalAlignment="Center" Width="120"/>
        </Grid>
        <ListBox Margin="41,108,59,753" ItemsSource="{Binding Path=SportViewModels}"  >
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <View:SportUserControl DataContext="{Binding}"  Margin="5"/>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
    </Grid>
</Window>

<UserControl
             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:ViewModel="clr-namespace:WpfApplicationMVVMTest.ViewModel" x:Class="SportUserControl" 
             mc:Ignorable="d" 
             d:DesignHeight="600" d:DesignWidth="600">
    <UserControl.Resources></UserControl.Resources>
    <UserControl.DataContext>
        <ViewModel:SportViewModel />
    </UserControl.DataContext>


    <Grid>
        <Grid x:Name="Grid1" HorizontalAlignment="Left" Margin="31,26,0,0" VerticalAlignment="Top">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="Auto"/>
                <ColumnDefinition Width="Auto"/>
            </Grid.ColumnDefinitions>
            <Grid.RowDefinitions>
                <RowDefinition Height="Auto"/>
                <RowDefinition Height="Auto"/>
            </Grid.RowDefinitions>
            <Label Content="Favourite Professional Team:" Grid.Column="0" HorizontalAlignment="Left" Margin="3" Grid.Row="0" VerticalAlignment="Center"/>
            <TextBox x:Name="FavouriteProfessionalTeamTextBox" Grid.Column="1" HorizontalAlignment="Left" Height="23" Margin="3" Grid.Row="0" Text="{Binding Sport1.FavouriteProfessionalTeam, Mode=TwoWay, NotifyOnValidationError=true, ValidatesOnExceptions=true}" VerticalAlignment="Center" Width="120"/>
            <Label Content="Sport Name:" Grid.Column="0" HorizontalAlignment="Left" Margin="3" Grid.Row="1" VerticalAlignment="Center"/>
            <TextBox x:Name="SportNameTextBox" Grid.Column="1" HorizontalAlignment="Left" Height="23" Margin="3" Grid.Row="1" Text="{Binding Sport1.SportName, Mode=TwoWay, NotifyOnValidationError=true, ValidatesOnExceptions=true}" VerticalAlignment="Center" Width="120"/>
        </Grid>

    </Grid>
</UserControl>