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我有一个MyViewModel,其中包含标量属性和集合属性。

public class MyViewModel :
    System.ComponentModel.INotifyPropertyChanged,
    System.ComponentModel.IDataErrorInfo
{
    public MyViewModel()
    {
        List<SelectableObject> list = new List<SelectableObject>();
        foreach (var weekDay in System.Threading.Thread.CurrentThread.CurrentCulture.DateTimeFormat.DayNames)
        {
            list.Add(new SelectableObject() { Name = weekDay, IsSelected = false });
        }
        WeekDays = list;
    }
    public string Catalog { get; set; }
    public DateTime CreationTime { get; set; }
    public DateTime ModificationTime { get; set; }

    public IEnumerable<SelectableObject> WeekDays { get; private set; }

    public ICommand SaveCommand { get; private set; }

    public string Error
    {
        get { return string.Empty; }
    }

    public string this[string columnName]
    {
        get
        {
            var errorResult = string.Empty;

            switch (columnName)
            {
                case "CreationTime":
                    // Validation logic
                    break;
                case "ModificationTime":
                    // Validation logic
                    break;
                default:
                    break;
            }

            return errorResult;
        }
    }
}

可选对象类:

public class SelectableObject : System.ComponentModel.INotifyPropertyChanged
{
    public string Name { get; set; }
    public bool IsSelected { get; set; }
}

我想通过SaveCommand操作<Button />的IsEnabled属性,并且我希望它启用,前提是表单上没有错误。但我不知道如何验证这一点:必须至少选择一个 WeekDay。

是的,我可以监听WeekDays集合中每个对象的PropertyChanged事件,但在这种情况下,验证逻辑将与IDataErrorInfo接口分离。

这个问题有什么解决办法吗?如何将集合的验证逻辑放入IDataErrorInfo接口?

4

1 回答 1

1

只需在您的canexecute中执行您的逻辑吗?

视图模型:

private DelegateCommand _save;

public ICommand SaveCommand
{
  get {return this._save ?? (this._save = new DelegateComamnd(this.MyExecuteMethod, this.MyCanExecuteMethod));}
 }

private bool MyCanExecuteMethod()
{
   return this.WeekDays.Any(x=>x.IsSelected) && string.IsNullOrWhiteSpace(this.Error);
}

ps:如果有任何错误,error 应该是非空的。

于 2012-07-30T07:36:29.387 回答