How to implement INotifyDataErrorInfo for Datarow - silverlight

Question

i have a datarow class that implements Dynamicobject and INotifyPropertyChanged and INotifyDataErrorInfo
Also have a property called 'GridData'(datarows) in this class that is bound to xaml for displaying in the grid
May i know how to implement public IEnumerable GetErrors(string propertyName)
correctly since 'GridData' property can have many property bags
Thanks

Answer 1

//This is your row... more or less.
public class GridData : DynamicObject, INotifyDataErrorInfo
{
private Dictionary<string, object> _propertyValues = new Dictionary<string, object>();
//this object holds your errors.
private Dictionary<string, List<ValidationResult>> _errorsContainer = new Dictionary<string, List<ValidationResult>>();
//when this fires it notifies the UI the errors of this object have changed.
public event EventHandler<DataErrorsChangedEventArgs> ErrorsChanged;
//This tells the UI there are errors.
public bool HasErrors
{
get { return this._errorsContainer.Count > 0; }
}
//this allows the UI to retrieve all errors for a given property
public IEnumerable GetErrors(string propertyName)
{
return this._errorsContainer[propertyName];
}
//This sets the error for a given property and fires the errors changed event
protected void SetError(string propertyName, IEnumerable<ValidationResult> errors)
{
List<ValidationResult> existingErrors;
if(this._errorsContainer.TryGetValue(propertyName, out existingErrors) != true)
{
this._errorsContainer[propertyName] = errors.ToList();
}
else
{
existingErrors.AddRange(errors);
}
this.RaiseErrorsChanged(propertyName);
}
//This clears the errors for a given property
protected void ClearErrors(string propertyName)
{
this._errorsContainer.Remove(propertyName);
this.RaiseErrorsChanged(propertyName);
}
//This raises the event that the errors of this object have changed.
protected void RaiseErrorsChanged(string propertyName)
{
if(this.ErrorsChanged != null)
{
this.ErrorsChanged(this, new DataErrorsChangedEventArgs(propertyName));
}
}
//inherited from dynamic object this returns the value for a given property.
public override bool TryGetMember(GetMemberBinder binder, out object result)
{
//this gives you the name of the property.
string name = binder.Name;
return _propertyValues.TryGetValue(name, out result);
}
//inherited from dynamic object, this is called when a property is set.
public override bool TrySetMember(SetMemberBinder binder, object value)
{
string propertyName = binder.Name;
List<ValidationResult> validationErrors = new List<ValidationResult>();
//store the value in the propertyValues regardless if it is erroneous.
_propertyValues[propertyName] = value;
//this is where you test the value of the property.
if(value /* whatever condition you use to test it */)
{
//no errors so update the ui.
this.ClearErrors(propertyName);
}
else
{
//there was an error for this value.
ValidationResult result = new ValidationResult("The value is wrong.");
//add the error to the list of errors for this property
validationErrors.Add(result);
//update the error container telling it there are errors for this property.
//fire the errors changed event, and update ui.
this.SetError(propertyName, validationErrors);
}
return true;
}
}