Disable button if validation in model has error
Hi I make validation on error in my model class.
public class CurrentUser:IDataErrorInfo, INotifyPropertyChanged
{
//...
private string _validationResult;
private string _nick;
public string Nick
{
get { return _nick; }
set
{
_nick = value;
NotifyPropertyChanged("Nick");
}
}
public string ValidationResult
{
get { return _validationResult; }
private set
{
_validationResult = value;
NotifyPropertyChanged("ValidationResult");
}
}
#region Implementation of INotifyPropertyChanged
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged(String info)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(info));
}
}
#endregion
#region Implementation of IDataErrorInfo
private string NickValid()
{
if (string.IsNullOrEmpty(Nick))
{
return NickNull;
}
if (Regex.IsMatch(Nick, "[^a-zA-Z0-9-_.]"))
{
return NickInvalidCharacters;
}
return string.Empty;
}
public string Error
{
get { throw new NotImplementedException(); }
}
public string this[string propertyName]
{
get
{
ValidationResult = string.Empty;
switch (propertyName)
{
case "Nick":
ValidationResult = NickValid();
break;
default:
break;
}
return ValidationResult;
}
}
#endregion
}
This model class I use in view model and I bind Nick property of model class to the Text property of comboBox control.
Also I bind method LogOn from view model class on button click event in view. I would like disabale button if validation in model class has error:
View model:
[Export(typeof(ILogOnViewModel))]
[PartCreationPolicy(CreationPolicy.NonShared)]
public class LogOnViewModel : Screen, ILogOnViewModel,
IPartImportsSatisfiedNotification
{
public C开发者_StackOverflowurrentUser CurrentUser { get; set; }
public bool CanLogOn
{
get
{
return string.IsNullOrWhiteSpace(CurrentUser.ValidationResult);
}
}
//bind on button click event
public void LogOn()
{}
}
Solution is simple set CanLogOn property on false if validation in CurrentUser (object) property has error.
But I don’t how notify property CanLogOn that in model class is not error. I run app and button is still disabled.
I need achive this behavior in model:
public string ValidationResult
{
get { return _validationResult; }
private set
{
_validationResult = value;
NotifyPropertyChanged("ValidationResult");
//notify property CanLogOn in view model class
}
}
Any advice? Thank.
Attach an event handler to the PropertyChanged
event of the user in your viewmodel:
CurrentUser.PropertyChanged += new PropertyChangedEventHandler(CurrentUser_PropertyChanged);
Add send a notification if the ValidationResult
changes:
void CurrentUser_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
if (e.PropertyName == "ValidationResult") NotifyPropertyChanged("CanLogOn");
}
Note: If your reference CurrentUser
is overwritten you need to add the event handler to the new object. You could do this by placing the attachment code in the setter of CurrentUser
.
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