Xamarin Forms ConverterParameter XAML error Invalid Property Path Syntax

Question

I have a text binding in my XAML as follows:

Text="{Binding Converter={StaticResource ColumnToCaption}, ConverterParameter=-1}"

It simply takes the column number and looks up what the caption should be for that column based on data I have stored in a collection. That has been working fine but after one of the last set of upgrades to Visual Studio / Xamarin forms, the XAML intelisense started generating the error "Invalid Property Value". I didn't think much of it because the app seemed to work. Then some weird things started happing in my app and I noticed in my error list, I have a 43 "Invalid Property Value" errors listed (basically one for every place I use the ConverterParameter).

I double checked the MS documentation to ensure nothing changed (this link https://learn.microsoft.com/en-us/xamarin/xamarin-forms/app-fundamentals/data-binding/converters) and it still shows passing the value in as a number is OK. Here is the example from the MS documentation:

 <Label Text="{Binding Red, Converter={StaticResource doubleToInt}, ConverterParameter=255,
     StringFormat='Red = {0:X2}'}" />

I am simply trying to rule this out as the source of my problem but I cannot seem to find out how to get the error to go away. Any assistance would be appreciated.

OH here is the converter code just so you can see it:

public class ColumnToCaption : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        string ls_ReturnValue = ""; 
        try
        {
            if (System.Convert.ToInt32(parameter.ToString()) < 0)
            {
                if (App.gvm_AppSettings.AutoExpire)
                {
                    ls_ReturnValue = AppResources.Time;
                }
                else
                {
                    ls_ReturnValue = AppResources.CheckedIn;
                }
            }
            else
            {
                ls_ReturnValue = App.gvm_AppSettings.FormFieldCaptionText(Int32.Parse(parameter.ToString()));
            }
        }
        catch (Exception ex)
        {
            App.ProcessException(ex);
        }

        return ls_ReturnValue;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

Answer 1

Could you not add a string resource?

...
<ContentPage.Resources>
    <ResourceDictionary>
        <converters:DoubleToInt x:Key="doubleToInt" />
        <x:String x:Key="twoFiveFive">255</x:String>
    </ResourceDictionary>
</ContentPage.Resources>
<ContentPage.Content>
...
    <Label Text="{Binding Red, Converter={StaticResource doubleToInt}, ConverterParameter={StaticResource twoFiveFive}}" .../>
...
</ContentPage.Content>