IDataErrorInfo:未验证输入

时间:2009-03-11 05:43:03

标签: c# wpf validation idataerrorinfo

我有一个包含文本框的用户控件。我有一个名为Person的类,它实现了IDataErrorInfo接口:

class Person : IDataErrorInfo
{
private bool hasErrors = false;
#region IDataErrorInfo Members

        public string Error
        {            
            get 
            {
                string error = null;
                if (hasErrors)
                {
                    error = "xxThe form contains one or more validation errors";
                }
                return error;
            }
        }

        public string this[string columnName]
        {
            get 
            {
                return DoValidation(columnName);
            }
        }
        #endregion
}

现在,usercontrol公开了一个名为SetSource的方法,代码通过该方法设置绑定:

public partial class TxtUserControl : UserControl 
    {          
        private Binding _binding;

        public void SetSource(string path,Object source)
        {
            _binding = new Binding(path);
            _binding.Source = source;
            ValidationRule rule;
            rule = new DataErrorValidationRule();
            rule.ValidatesOnTargetUpdated = true;            
            _binding.ValidationRules.Add(rule);
            _binding.ValidatesOnDataErrors = true;
            _binding.UpdateSourceTrigger = UpdateSourceTrigger.LostFocus;
            _binding.NotifyOnValidationError = true;            
            _binding.ValidatesOnExceptions = true;
            txtNumeric.SetBinding(TextBox.TextProperty, _binding);                
        }
...
}

包含用户控件的WPF窗口包含以下代码:

public SampleWindow()
    {
        person= new Person();
        person.Age = new Age();
        person.Age.Value = 28;

        numericAdmins.SetSource("Age.Value", person);
    }
    private void btnOk_Click(object sender, RoutedEventArgs e)
    {         

        if(!String.IsNullOrEmpty(person.Error))
        {
            MessageBox.Show("Error: "+person.Error);
        }
    }

鉴于此代码,绑定工作正常,但验证永远不会被触发。这段代码怎么了?

2 个答案:

答案 0 :(得分:3)

您的Age课程需要实施IDataErrorInfo。我们不会要求您的Person课程验证Age的属性。

如果这不是一个选项,我为WPF编写了一个可扩展的验证系统,足以支持这一点。 URL在这里:

在ZIP中是描述它的word文档。

编辑:这是年龄可以实现IDataErrorInfo而不太聪明的一种方式:

class Constraint 
{
    public string Message { get; set; }
    public Func<bool> Validate;
    public string Name { get; set; }
}

class Age : IDataErrorInfo
{
    private readonly List<Constraint> _constraints = new List<Constraint>();

    public string this[string columnName]
    {
        get 
        {
            var constraint = _constrains.Where(c => c.Name == columnName).FirstOrDefault();
            if (constraint != null)
            {
                if (!constraint.Validate())
                {
                    return constraint.Message;
                }
            }
            return string.Empty;
        }
    }
}

class Person
{
    private Age _age;

    public Person() 
    {
        _age = new Age(
            new Constraint("Value", "Value must be greater than 28", () => Age > 28);
    }
}

另见此链接:

http://www.codeproject.com/KB/cs/DelegateBusinessObjects.aspx

答案 1 :(得分:0)

另一种选择可能是在Age类上实现IDataErrorInfo,并在其上创建一个事件,如OnValidationRequested,应由Person类捕获。这样,您可以根据Person类的其他属性验证Age字段。