Question

   // Child View model
    public class ChildViewModel
    {
        public ChildModel CurrentChild { get; set; }
        private readonly List<ChildModel> _childList = new List<ChildModel>();
        public ChildViewModel()
        {
           CurrentChild = new ChildModel();
        }
        public static ChildViewModel Create()
        {
           return ViewModelSource.Create<ChildViewModel>();
        }
        public void SaveMessage()
        {
           _childList.Add(ChildMessage);
        }
    }

    //parent ViewModel public class ParentViewModel {
        public ParentViewModel() {
            Child = ChildViewModel.Create();
        }
        public virtual ChildViewModel Child { 
            get;
            protected set;
        }
     }
//Parent View 
fluentApi.BindCommand(simpleButton , x => x.Child.Save());
//Child View 
fluentApi.SetObjectDataSourceBinding(ChildModelBindingSource, x => x.CurrentChild);

我在usercontrol中使用子视图模型中的对象CurrentChild绑定控件。当我在父视图中单击simpleButton以在子视图模型中调用save方法但模型对象（CurrentChild）为null时（它不会更新它的vlaue）。那么我怎样才能更新基于子视图模型的父视图模型属性。

Answer 1

以下是适用于我的更正代码：

查看方：

var fluent = mvvmContext1.OfType<ParentViewModel>();
fluentApi.BindCommand(btnSave, x => x.Child.Save());
fluentApi.SetObjectDataSourceBinding(childModelbindingSource, x => x.Child.CurrentChild);

ViewModels方面：

// Child View model
public class ChildViewModel {
    readonly List<ChildModel> _childList = new List<ChildModel>();
    public ChildViewModel() {
        CurrentChild = new ChildModel();
    }
    public static ChildViewModel Create() {
        return ViewModelSource.Create<ChildViewModel>();
    }
    public ChildModel CurrentChild {
        get;
        private set;
    }
    public void Save() {
        _childList.Add(CurrentChild);
    }
}
// Parent ViewModel 
public class ParentViewModel {
    public ParentViewModel() {
        Child = ChildViewModel.Create();
    }
    public virtual ChildViewModel Child {
        get;
        protected set;
    }
}
public class ChildModel { 
    // ...
}

<强>更新
要使您的示例正常工作，您应该在初始化绑定之前将子ViewModel实例传递给ChildView ：

// MainView public MainView() { InitializeComponent(); if(!mvvmContext1.IsDesignMode) InitializeBindings(); } void InitializeBindings() { var fluent = mvvmContext1.OfType<MainViewModel>(); fluent.BindCommand(simpleButton1, x => x.ChildViewModel.Save()); var childView = new ChildView(fluent.ViewModel.ChildViewModel); // pass the ViewModel this.panel1.Controls.Add(childView); } // Child View public ChildView(ChildViewModel viewModel) { InitializeComponent(); if(!mvvmContext1.IsDesignMode) { mvvmContext1.SetViewModel(typeof(ChildViewModel), viewModel); // before any bindings InitializeBindings(); } } void InitializeBindings() { var fluent = mvvmContext1.OfType<ChildViewModel>(); fluent.SetObjectDataSourceBinding(childModelBindingSource, x => x.ChildData); fluent.BindCommand(simpleButton1, x => x.Save()); }

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如何从父视图模型访问子视图模型对象？

1 个答案: