WPF在后面的代码中初始化对象并在viewmodel中使用该对象

Question

I need to initialize object in xaml.cs code behind and then use that object in my binded viewmodel. But when I do that the object properly initialize, but viewmodel acts like it's still null.

MainWindow.xaml

<oxys:PlotView x:Name="dataPlot" Model="{Binding DataPlotModel}" Margin="10,10,185,39"/>

MainWindow.xaml.cs

MainWindowViewModel viewModel;

public MainWindow()
{
    viewModel = new MainWindowViewModel();
    DataContext = viewModel;

    InitializeComponent();

    PlotModel DataPlotModel = new PlotModel();
    dataPlot.Model = DataPlotModel;
}

MainWindowViewModel.cs

public PlotModel DataPlotModel { get; set; }

And the DataPlotModel in viewmodel is always null unless I initialize it strictly in viewmodel.

Answer 1

You need to set the DataPlotModel property of the view model somewhere:

MainWindowViewModel viewModel;

public MainWindow()
{
    viewModel = new MainWindowViewModel();
    DataContext = viewModel;

    InitializeComponent();

    viewModel.DataPlotModel = new PlotModel(); //<-- Set the view model property
}

You should set the view model property rather than setting the property of control directly as this will break the binding.