Implement a BaseClass which support:

- INotifyPropertyChanged
- INotifyDataErrorInfo

src/MahApps.Metro.Demo_v2/Core/BaseClass.cs

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+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace MahApps.Demo.Core
+{
+ public class BaseClass : INotifyPropertyChanged, INotifyDataErrorInfo
+ {
+ #region INotifyPropertyChanged
+
+ // This event tells the UI to update
+ public event PropertyChangedEventHandler PropertyChanged;
+
+ public void RaisePropertyChanged(string PropertyName)
+ {
+ PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(PropertyName));
+ }
+
+ #endregion INotifyPropertyChanged
+
+ #region INotifyDataErrorInfo
+
+ public event EventHandler<DataErrorsChangedEventArgs> ErrorsChanged;
+
+ public bool HasErrors => _errorsByPropertyName.Count > 0;
+
+ private readonly Dictionary<string, List<string>> _errorsByPropertyName = new Dictionary<string, List<string>>();
+
+ public IEnumerable GetErrors(string propertyName)
+ {
+ if (string.IsNullOrEmpty(propertyName))
+ {
+ return null;
+ }
+ else
+ {
+ return _errorsByPropertyName.ContainsKey(propertyName)
+ ? _errorsByPropertyName[propertyName]
+ : null;
+ }
+ }
+
+ public bool GetHasError(string PropertyName)
+ {
+ return _errorsByPropertyName.ContainsKey(PropertyName);
+ }
+
+ public void AddError(string propertyName, string error)
+ {
+ if (!_errorsByPropertyName.ContainsKey(propertyName))
+ _errorsByPropertyName[propertyName] = new List<string>();
+
+ if (!_errorsByPropertyName[propertyName].Contains(error))
+ {
+ _errorsByPropertyName[propertyName].Add(error);
+ OnErrorsChanged(propertyName);
+ }
+ }
+
+ public void ClearErrors(string propertyName)
+ {
+ if (_errorsByPropertyName.ContainsKey(propertyName))
+ {
+ _errorsByPropertyName.Remove(propertyName);
+ OnErrorsChanged(propertyName);
+ }
+ }
+
+ public void OnErrorsChanged(string propertyName)
+ {
+ ErrorsChanged?.Invoke(this, new DataErrorsChangedEventArgs(propertyName));
+ }
+
+ #endregion INotifyDataErrorInfo
+ }
+}