Question

我想将SecondViewModel SecondProperty 的值传递给ViewModel myProperty ，并在 TextBlock 上显示该值。我希望在SecondViewModel中完成编码。希望一切都清楚。

感谢Advance的帮助。

查看：

EMPLOYEE_ID HOURS_ABSENT    DATE    3DAYS   5DAYS
x1  7.500000    2017-01-16 00:00:00.000 0   0
x1  7.500000    2017-01-30 00:00:00.000 0   1
x1  7.500000    2017-01-31 00:00:00.000 0   0
x1  7.500000    2017-02-01 00:00:00.000 0   0
x1  7.500000    2017-02-02 00:00:00.000 0   0
x1  7.500000    2017-02-03 00:00:00.000 0   0
x1  7.500000    2017-02-06 00:00:00.000 0   0
x1  7.500000    2017-02-07 00:00:00.000 0   0
x1  7.500000    2017-05-22 00:00:00.000 0   0
X2  7.500000    2016-11-29 00:00:00.000 1   0
X2  7.500000    2016-11-30 00:00:00.000 0   0
X2  7.500000    2016-12-01 00:00:00.000 0   0

ViewModel：

<TextBlock Text="{Binding Path=myProperty}"/>

SecondViewModel：

private int _myProperty;
public int myProperty
{
    get { return _myProperty; }
    set { _myProperty = value; OnPropertyChanged("myProperty"); }
}

Answer 1

根据您的评论，假设ViewModel拥有SecondViewModel个项目的集合，则需要为PropertyChangedEvent的每个实例设置SecondViewModel来触发{{1} }刷新。例如...

ViewModel.myProperty

顺便说一句，您永远不要使用“魔术字符串”调用public class ViewModel { private List<SecondViewModel> _secondViewModels = new List<SecondViewModel>(); public IEnumerable<SecondViewModel> SecondViewModels => _secondViewModels; public int myProperty => _secondViewModels.Sum(vm => vm.SecondProperty); public void AddSecondViewModel(SecondViewModel vm) { _secondViewModels.Add(vm); vm.PropertyChanged += (s, e) => OnPropertyChanged(nameof(myProperty)); OnPropertyChanged(nameof(myProperty)); } }-改为使用OnPropertyChanged()。

Answer 2

如果需要，您应该创建一个VM数据源以在第一个VM中创建一个依赖项。

public class YourViewModelDataSource
 {

private ViewModel viewModel;
private SecondViewModel secondViewModel;

public YourViewModelDataSource(ViewModel viewModel, SecondViewModel secondViewModel)
    {
      this.viewModel = viewModel;
      this.secondViewModel = secondViewModel;
    }

public void CreateDataSource()
    {
      this.secondViewModel.PropertyChanged += this.OnSecondViewModelPropertyChanged;
    }

private void OnSecondViewModelPropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            switch (e.PropertyName)
            {
                //As pointed in comments, you need to have the second property in your first ViewModel then do this.
                case "SecondProperty":
                    this.viewModel.myProperty = this.secondViewModel.SecondProperty;
                    break;
            }
        }
  }

在创建VM时，请使用此类创建依赖关系。每当SecondViewModel SecondProperty更改时，ViewModel myProperty将被引发。我希望一切都清楚了，让我知道您是否还需要其他东西

如何将属性值传递给wpf mvvm中另一个类的属性

2 个答案: