ComboBox 不填充 Silverlight MVVM 中的数据

Question

嗯，我不知道还能做什么。我检查了代码，一切正常。

所以我的问题是组合框没有填充任何数据，我检查了 ObservableCollection 集并且它有数据但它没有任何填充

我使用了 MVVM 模式，一切顺利，但没有调用 GET

我可以得到一些提示可能是什么原因，因为我没有想法

StudentDetailView.xaml

    <Grid x:Name="LayoutRoot" Background="White">
    <Grid DataContext="{Binding}" HorizontalAlignment="Left" Margin="12,12,0,0" Name="grid1" VerticalAlignment="Top" Height="176" Width="376">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="Auto" />
            <ColumnDefinition Width="Auto" />
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="31*" />
        </Grid.RowDefinitions>
        <sdk:Label Content="Clasa ID:" Grid.Column="0" Grid.Row="0" HorizontalAlignment="Left" Margin="3" VerticalAlignment="Center" />
        <ComboBox Grid.Column="1" Grid.Row="0" Height="23" HorizontalAlignment="Left" Margin="3" 
                  Name="clasaIDComboBox" VerticalAlignment="Center" Width="120"
                  DisplayMemberPath="Nume" 
                  SelectedValuePath="ID" />
        <sdk:Label Content="Data Nasterii:" Grid.Column="0" Grid.Row="1" HorizontalAlignment="Left" Margin="3" VerticalAlignment="Center" />
        <sdk:DatePicker Grid.Column="1" Grid.Row="1" Height="23" HorizontalAlignment="Left" Margin="3" Name="data_NasteriiDatePicker" VerticalAlignment="Center" Width="120" />
        <sdk:Label Content="ID:" Grid.Column="0" Grid.Row="2" HorizontalAlignment="Left" Margin="3" VerticalAlignment="Center" />
        <TextBox Grid.Column="1" Grid.Row="2" Height="23" HorizontalAlignment="Left" Margin="3" Name="iDTextBox" VerticalAlignment="Center" Width="120" />
        <sdk:Label Content="Liceu ID:" Grid.Column="0" Grid.Row="3" HorizontalAlignment="Left" Margin="3" VerticalAlignment="Center" />
        <TextBox Grid.Column="1" Grid.Row="3" Height="23" HorizontalAlignment="Left" Margin="3" Name="liceuIDTextBox" VerticalAlignment="Center" Width="120" />
        <sdk:Label Content="Nume:" Grid.Column="0" Grid.Row="4" HorizontalAlignment="Left" Margin="3" VerticalAlignment="Center" />
        <TextBox Grid.Column="1" Grid.Row="4" Height="23" HorizontalAlignment="Left" Margin="3" Name="numeTextBox" VerticalAlignment="Center" Width="120" />

    </Grid>
    <Button Content="Save Student" Height="23" HorizontalAlignment="Left" Margin="194,232,0,0" Name="btnSaveStudent" VerticalAlignment="Top" Width="95" Click="btnSaveStudent_Click" />
    <Button Content="Cancel" Height="23" HorizontalAlignment="Left" Margin="295,232,0,0" Name="btnCancelStudent" VerticalAlignment="Top" Width="75" Click="btnCancelStudent_Click" />
    <ct:ValidationSummary Width="300" Margin="12,194,70,23" />
</Grid>

StudentDetailView.xaml.cs

public StudentDetailView()
    {
        InitializeComponent();
        clasaIDComboBox.SetBinding(ComboBox.ItemsSourceProperty, new Binding() { Path = new PropertyPath("LstHighSchool"), Mode = BindingMode.TwoWay });
        clasaIDComboBox.SetBinding(ComboBox.SelectedValueProperty, new Binding() { Path = new PropertyPath("SelectedHighSchool"), Mode = BindingMode.TwoWay, NotifyOnValidationError = true, ValidatesOnExceptions = true });
}

以及来自 StudentViewModel.cs 的部分代码

        private void AddNewStudentView(object param)
    {
        StudentDetailView addNewStudentView = new StudentDetailView();
        addNewStudentView.DataContext = new Student();
        var sdfsdfj = new StudentViewModel();

         LoadOperation<Liceu> li = DomainContext.Load(DomainContext.GetLiceusQuery());
        li.Completed += (s, e) =>
        {
            LstHighSchool = (s as LoadOperation<Liceu>).Entities.ToObservableCollection();
        };

        addNewStudentView.Closed += delegate
        {
            if (addNewStudentView.DialogResult == true)
            {
                Student newStudent = addNewStudentView.DataContext as Student;



                if (string.IsNullOrEmpty(newStudent.Nume))
                {
                    newStudent.ValidationErrors.Add(new ValidationResult("Numele nu poate sa fie invalid",new string[]{"Nume"}));
                }
                if (!newStudent.LiceuID.HasValue)
                {
                    newStudent.ValidationErrors.Add(new ValidationResult("Liceu ID este gol", new string[] { "LiceuID" }));
                }

                if (!newStudent.HasValidationErrors)
                {


                    if (newStudent != null)
                    {
                        DomainContext.Students.Add(newStudent);
                        LstStudents.Add(newStudent);

                    }
                }
                else
                {
                    addNewStudentView.Show();

                }
            }

        };

        addNewStudentView.Show();
        OnPropertyChanged("LstHighSchool");


    }
    private bool CanWork(object param)
    {
        return true; //for the moment this remains true, cause you can add all the time a new student, but this can be changed if there must be some conditions

    }

    private ObservableCollection<Liceu> _lstHighSchool;
    public ObservableCollection<Liceu> LstHighSchool
    {
        get
        {
            return _lstHighSchool;
        }
        set
        {
            _lstHighSchool = value;
            OnPropertyChanged("LstHighSchool");
        }
    }

    private int _selectedHighSchool;
    public int SelectedHighSchool
    {
        get
        {
            return _selectedHighSchool;
        }
        set
        {
            _selectedHighSchool = value;
            OnPropertyChanged("SelectedHighSchool");
        }
    }



    #endregion

Answer 1

首先，去掉Grid DataContext="{Binding}"，然后你在xaml中的组合框应该是这样的：

<ComboBox Grid.Column="1" Grid.Row="0" Height="23" HorizontalAlignment="Left" Margin="3" 
                  VerticalAlignment="Center" Width="120" DisplayMemberPath="Nume" 
                  SelectedValuePath="ID" ItemsSource="{Binding LstHighSchool}" 
                  SelectedValue="{Binding SelectedHighSchool}" />

其次，你的视图代码应该是这样的，

public StudentDetailView()
{
    InitializeComponent();
    this.DataContext= new StudentViewModel();
}

最后，在 StudentViewModel.cs 中应该有一个名为 LstHighSchool 的属性，看起来不错。