Binding, Error, Validation, Validation rule, Wpf

public static class Validator

{

   private static Dictionary<Type, List<DependencyProperty>> PropertiesReflectionChace = new Dictionary<Type, List<DependencyProperty>>();

   private static List<DependencyProperty> GetDPs(Type t)

   {

      if (PropertiesReflectionChace.ContainsKey(t))

         return PropertiesReflectionChace[t];

      FieldInfo[] properties = t.GetFields(BindingFlags.Public | BindingFlags.GetProperty |

           BindingFlags.Static | BindingFlags.FlattenHierarchy);

      // we cycle and store only the dependency properties

      List<DependencyProperty> dps = new List<DependencyProperty>();

      foreach (FieldInfo field in properties)

         if (field.FieldType == typeof(DependencyProperty))

            dps.Add((DependencyProperty)field.GetValue(null));

      PropertiesReflectionChace.Add(t, dps);

      return dps;

   }

   /// <summary>

   /// checks all the validation rule associated with objects,

   /// forces the binding to execute all their validation rules

   /// </summary>

   /// <param name="parent"></param>

   /// <returns></returns>

   public static bool IsValid(DependencyObject parent)

   {

      // Validate all the bindings on the parent

      bool valid = true;

      // get the list of all the dependency properties, we can use a level of caching to avoid to use reflection

      // more than one time for each object

      foreach (DependencyProperty dp in GetDPs(parent.GetType()))

      {

         if (BindingOperations.IsDataBound(parent, dp))

         {

            Binding binding = BindingOperations.GetBinding(parent, dp);

            if (binding.ValidationRules.Count > 0)

            {

               BindingExpression expression = BindingOperations.GetBindingExpression(parent, dp);

               switch (binding.Mode)

               {

                  case BindingMode.OneTime:

                  case BindingMode.OneWay:

                     expression.UpdateTarget();

                     break;

                  default:

                     expression.UpdateSource();

                     break;

               }

               if (expression.HasError) valid = false;

            }

         }

      }

      // Validate all the bindings on the children

      for (int i = 0; i != VisualTreeHelper.GetChildrenCount(parent); ++i)

      {

         DependencyObject child = VisualTreeHelper.GetChild(parent, i);

         if (!IsValid(child)) { valid = false; }

      }

      return valid;

   }

}