我通过ListBox
绑定了一个WPF ItemsSource
。
所选项目以双向模式绑定到VM上的属性。
当我将值分配给集合中不存在的模型属性时,我希望在UI上“取消选择”所选项目。
这可能吗?如果没有,是否有清除所选项目的替代方案?
请记住我正在使用MVVM模式,因此我无法从代码中访问列表本身。
谢谢!
答案 0 :(得分:3)
我将假设以下内容:
如果上述内容不准确,请提供有关您的实施的更多信息。
您的viewmodel应该有一些看起来像这样的代码:
public class VM : INotifyPropertyChanged
{
private ObservableCollection<Student> vmlist = new ObservableCollection<Student>();
private Student vmselecteditem;
public event PropertyChangedEventHandler PropertyChanged;
public VM()
{
PropertyChanged = new PropertyChangedEventHandler(VM_PropertyChanged);
}
private void VM_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
}
public ObservableCollection<Student> VM_List
{
get
{
return vmlist;
}
}
public Student VM_SelectedItem
{
get
{
return vmselecteditem;
}
set
{
vmselecteditem = value;
}
}
public void AddNewStudent(Student NewStudent)
{
VM_SelectedItem = null;
PropertyChanged(this, new PropertyChangedEventArgs("VM_SelectedItem"));
VM_SelectedItem = NewStudent;
SaveStudent();
PropertyChanged(this, new PropertyChangedEventArgs("VM_SelectedItem"));
//The last line is optional, if you want to select the new student just added.
}
private void SaveStudent()
{
//A fake operation to save the student.
//To stick with MVVM, the save function should be in the model
//And this function should just call the one in the model.
BackgroundWorker b = new BackgroundWorker();
b.DoWork += new DoWorkEventHandler(b_DoWork);
b.RunWorkerCompleted += new RunWorkerCompletedEventHandler(b_RunWorkerCompleted);
b.RunWorkerAsync();
}
private void AddStudentToList()
{
VM_List.Add(VM_SelectedItem);
}
private void b_DoWork(object sender, DoWorkEventArgs e)
{
//Simulating a long save operation
System.Threading.Thread.Sleep(2000);
}
private void b_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
AddStudentToList();
}
}