WPF 4.5 中的 INotifyDataErrorInfo 和异步数据验证

使用 INotifyDataErrorInfo 和异步数据验证 进行 WPF 4.5 数据验证

csharp
public class Person : INotifyDataErrorInfo
{
    private string _name;
    private int _age;
    private Dictionary> _errors = new Dictionary>();
    public string Name
    {
        get { return _name; }
        set
        {
            _name = value;
            ValidateName();
        }
    }
    public int Age
    {
        get { return _age; }
        set
        {
            _age = value;
            ValidateAge();
        }
    }
    public bool HasErrors
    {
        get { return _errors.Count > 0; }
    }
    public event EventHandler ErrorsChanged;
    public IEnumerable GetErrors(string propertyName)
    {
        if (_errors.ContainsKey(propertyName))
            return _errors[propertyName];
        else
            return null;
    }
    private void ValidateName()
    {
        if (string.IsNullOrEmpty(Name))
        {
            AddError("Name", "Name cannot be empty");
        }
        else
        {
            RemoveError("Name");
        }
    }
    private void ValidateAge()
    {
        if (Age < 0 || Age > 150)
        {
            AddError("Age", "Age must be between 0 and 150");
        }
        else
        {
            RemoveError("Age");
        }
    }
    private void AddError(string propertyName, string error)
    {
        if (!_errors.ContainsKey(propertyName))
        {
            _errors[propertyName] = new List();
        }
        if (!_errors[propertyName].Contains(error))
        {
            _errors[propertyName].Add(error);
            OnErrorsChanged(propertyName);
        }
    }
    private void RemoveError(string propertyName)
    {
        if (_errors.ContainsKey(propertyName))
        {
            _errors.Remove(propertyName);
            OnErrorsChanged(propertyName);
        }
    }
    private void OnErrorsChanged(string propertyName)
    {
        ErrorsChanged?.Invoke(this, new DataErrorsChangedEventArgs(propertyName));
    }
}