maui: changing a bound string from code does not update ui unless string is regenerated (mvvm)

This is my string:

public string EmptyViewText { get; set; } = "Please input a bin id first!*";

I have a simple command:

public async Task Entry(string barcode)
{
    MainThread.BeginInvokeOnMainThread(() =>
    {
        EmptyViewText = "Loading data...*";
        OnPropertyChanged();
    });
}

This is triggered.

This is my class:

public partial class BinViewModel : ObservableObject

The binding itself works, as I do see my values. But when I change the values from code, nothing happens.

The binding is super simple:

<Label Text="{Binding EmptyViewText}"  />

If I however disable the string and reenable it (re render it) it does show up with the new and correted text.

What is of issue here?

>Solution :

Your code is calling OnPropertyChanged() without an argument. Wherever that method is, it’s probably defined similar to this:

protected virtual void OnPropertyChanged([CallerMemberName] string? propertyName = null)
{
    PropertyChanged?.Invoke( this, new PropertyChangedEventArgs(propertyName));
}

The caller in this case is Entry not EmptyViewText. It’s going to fire a property changed event, but on the wrong property.

See if it makes a difference if you call it with an explicit argument:

public async Task Entry(string barcode)
{
    MainThread.BeginInvokeOnMainThread(() =>
    {
        EmptyViewText = "Loading data...*";
        OnPropertyChanged(nameof(EmptyViewText));
    });
}