✅ Creating ViewModel for Maui doesn't propagate changes
I am attempting to cleanup my Maui app a bit and wanted to create an abstract class
When I user ViewModel on an already functioning page, the properties are not being updated and displayed to the bound control.
ViewModel
SignUpViewModel
With this, ErrorMessage changes are not shown in the app where if I implment INotifyPropertyChanged directly, it works.
ViewModelViewModel that implements the boilerplate code for INotifyPropertyChangedINotifyPropertyChanged.When I user ViewModel on an already functioning page, the properties are not being updated and displayed to the bound control.
ViewModel
public abstract class ViewModel: INotifyPropertyChanged
{
public event PropertyChangedEventHandler? PropertyChanged;
protected virtual void OnPropertyChanged([CallerMemberName] string? propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
protected bool SetField<T>(ref T field, T value, [CallerMemberName] string? propertyName = null)
{
if (EqualityComparer<T>.Default.Equals(field, value)) return false;
field = value;
OnPropertyChanged(propertyName);
return true;
}
}public abstract class ViewModel: INotifyPropertyChanged
{
public event PropertyChangedEventHandler? PropertyChanged;
protected virtual void OnPropertyChanged([CallerMemberName] string? propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
protected bool SetField<T>(ref T field, T value, [CallerMemberName] string? propertyName = null)
{
if (EqualityComparer<T>.Default.Equals(field, value)) return false;
field = value;
OnPropertyChanged(propertyName);
return true;
}
}SignUpViewModel
using System.ComponentModel;
using System.Net.Mail;
using System.Runtime.CompilerServices;
using System.Windows.Input;
namespace ToolerMobile.Pages;
public class SignUpViewModel : ViewModel
{
private string _email = "", _errorMessage = "";
public string Email
{
get => _email;
set
{
_email = value;
ValidateForm();
}
}
public string ErrorMessage
{
get => _errorMessage;
private set
{
_errorMessage = value;
SetField(ref _errorMessage, value);
}
}
private void ValidateForm()
{
ErrorMessage = "";
try
{
if (_email.Length == 0)
{
return;
}
new MailAddress(_email);
}
catch (Exception e)
{
ErrorMessage = "Invalid email address.";
}
}using System.ComponentModel;
using System.Net.Mail;
using System.Runtime.CompilerServices;
using System.Windows.Input;
namespace ToolerMobile.Pages;
public class SignUpViewModel : ViewModel
{
private string _email = "", _errorMessage = "";
public string Email
{
get => _email;
set
{
_email = value;
ValidateForm();
}
}
public string ErrorMessage
{
get => _errorMessage;
private set
{
_errorMessage = value;
SetField(ref _errorMessage, value);
}
}
private void ValidateForm()
{
ErrorMessage = "";
try
{
if (_email.Length == 0)
{
return;
}
new MailAddress(_email);
}
catch (Exception e)
{
ErrorMessage = "Invalid email address.";
}
}With this, ErrorMessage changes are not shown in the app where if I implment INotifyPropertyChanged directly, it works.
