Question

我有以下课程，我已经实现了IDataErrorInfo接口，但它没有工作，即它没有进行验证。代码似乎很完美。我不知道为什么。我提出了一个断点，它甚至没有进入IDataErrorInfo Members区域。

产品类

[DataContract()]
public class Product : IDataErrorInfo
{
    [DataMember()]
    public string Name{get;set;}
    [DataMember()]
    public string Code{get;set;}

    #region IDataErrorInfo Members

    public string Error
    {
        get
        {
            return null;
        }
    }

    public string this[string property]
    {
        get
        {
            switch (property)
            {
                case "Name":
                    if (string.IsNullOrEmpty(Name))
                        return "Name is required";
                    break;
                case "Code":
                    if (string.IsNullOrEmpty(Code))
                        return "Code is required";
                    break;
                default:
                    break;
            }
            return null;
        }
    }

    #endregion

    public Product(string name, string code)
    {
        Name = name;
        Code = code;
    }
 }

绑定textbox

的XAML

<TextBox Grid.Column="1" 
                         HorizontalAlignment="Left" 
                         Height="23" 
                         Margin="24,9,0,0" 
                         TextWrapping="Wrap" 
                         VerticalAlignment="Top" 
                         Width="148" x:Name="txtName" 
                         Text="{Binding Name,Mode=TwoWay,ValidatesOnDataErrors=True}" 
                         MaxLength="50"/>

Answer 1

您需要使用INotifyPropertyChanged和IDataErrorInfo使对象可观察，以便绑定知道属性已更改，并在ValidatesOnDataErrors=True时检查是否存在任何错误

public class Product : IDataErrorInfo, INotifyPropertyChanged {
    string _name;
    [DataMember()]
    public string Name{
        get { return _name; }
        set {
            _name = value;
            NotifyPropertyChanged("Name");
        }
    }

    //...Other code removed for brevity

    public event PropertyChangedEventHandler PropertyChanged;

    protected void NotifyPropertyChanged(string propertyName) {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null) {
            handler(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

您甚至可以将属性更改的功能移到基类中以便重复使用

public abstract class PropertyChangedBase: INotifyPropertyChanged {

    public event PropertyChangedEventHandler PropertyChanged;

    protected void NotifyPropertyChanged(string propertyName) {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null) {
            handler(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

并像

一样使用它

public class Product : PropertyChangedBase, IDataErrorInfo {
    //Code removed for brevity
}

接口IDataErrorInfo不起作用

1 个答案: