Question

有没有办法将自定义验证错误添加到控件的错误列表中？我知道如何使用IDataErrorInfo，INotifyErrorInfo，ValidationAttribute等，但我想从代码中添加自定义验证错误。

Answer 1

Found a way:

First, create a public class for holding our error message:

public class TagModelError { private readonly String errorMessage;

    public TagModelError(String errorMessage)
    {
        this.errorMessage = errorMessage;
    }

    public Object Tag
    {
        get
        {
            return new Object();
        }
        set
        {
            throw new ValidationException(this.errorMessage);
        }
    }
}

Next, create a helper method:

public static void AddValidationError(this Control control, String errorMessage) { var expression = elm.GetBindingExpression(FrameworkElement.TagProperty);

    if (expression == null)
    {
        expression = control.SetBinding(FrameworkElement.TagProperty, new Binding("Tag")
        {               
            Mode = BindingMode.TwoWay,
            ValidatesOnExceptions = true,
            UpdateSourceTrigger = UpdateSourceTrigger.Explicit,
            Source = new TagModelError(errorMessage)
        }) as BindingExpression;
    }

    expression.UpdateSource();
}

I am using the Tag property because it is seldom required, but you can use another one. The trick here is to cause an exception when writing back to the model.

在Silverlight中添加自定义验证错误

1 个答案: