CODEWITHSUNDEEP
maui
Frank Mehlhop
Frank Mehlhop

Reputation: 2222

Maui Converter How to bind value

I have a StackLayout. This should be shown only, when a list from the ViewModel has more than one item. What is the problem?

I get the error message:

No property, BindableProperty, or event found for "Path", or mismatching type between value and property.

The Converter looks like that:

public class IntegerGreaterThanOneToBoolConverter : IMultiValueConverter
{
    public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
    {
        if (values == null)
        {
            return false;
        }


        return ((int)values[0]) > 1;
    }

    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
    {
        return null;
    }
}

I use the Converter at a Page like that:

<HorizontalStackLayout BindableLayout.ItemsSource="{Binding PageButtonList}" >

    <HorizontalStackLayout.IsVisible>
        <x:Binding Converter="{StaticResource AnyStringNotNullOrEmptyConverter}">
            <Binding Path="PageButtonList.Count" />
        </x:Binding>
    </HorizontalStackLayout.IsVisible>

Upvotes: 0

Views: 1182

Answers (2)

Frank Mehlhop
Frank Mehlhop

Reputation: 2222

Revised version:

public class IntegerGreaterThanOneToBoolConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value is null)
        {
            return false;
        }


        return ((int)value) > 1;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return null;
    }
}

using:

<HorizontalStackLayout BindableLayout.ItemsSource="{Binding PageButtonList}" 
                       IsVisible="{Binding PageButtonList.Count, Converter={StaticResource IntegerGreaterThanOneToBoolConverter}}">

Upvotes: 0

AllramEst
AllramEst

Reputation: 1449

Here is a possible solution.

The error is likely due to the way the converter is being used in the XAML. You are referencing a converter named AnyStringNotNullOrEmptyConverter in the XAML, but your converter is named IntegerGreaterThanOneToBoolConverter. Additionally, the use of x:Binding for the IsVisible property seems incorrect.

Here is a possible solution (Not Tested):

<HorizontalStackLayout BindableLayout.ItemsSource="{Binding PageButtonList}">
    <HorizontalStackLayout.IsVisible>
        <MultiBinding Converter="{StaticResource IntegerGreaterThanOneToBoolConverter}">
            <Binding Path="PageButtonList.Count" />
        </MultiBinding>
    </HorizontalStackLayout.IsVisible>
</HorizontalStackLayout>

Changes Made:

  1. Replaced the converter reference from AnyStringNotNullOrEmptyConverter to IntegerGreaterThanOneToBoolConverter.
  2. Used MultiBinding instead of x:Binding for the IsVisible property since the converter is an IMultiValueConverter.

Please ensure that the IntegerGreaterThanOneToBoolConverter is correctly added to the page's resources with the key IntegerGreaterThanOneToBoolConverter.

Example:

<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:YourNamespace" <!-- Replace 'YourNamespace' with the namespace where your converter is defined -->
             x:Class="YourPageClass"> <!-- Replace 'YourPageClass' with your page's class name -->

    <!-- Page Resources -->
    <ContentPage.Resources>
        <ResourceDictionary>
            <local:IntegerGreaterThanOneToBoolConverter x:Key="IntegerGreaterThanOneToBoolConverter"/>
        </ResourceDictionary>
    </ContentPage.Resources>

    <!-- Page Content -->
    <!-- ... your page content ... -->

</ContentPage>

To add it to the entire application, here is an example of the App.xaml:

<Application xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:YourNamespace" <!-- Replace 'YourNamespace' with the namespace where your converter is defined -->
             x:Class="YourAppNamespace.App">

    <!-- Application Resources -->
    <Application.Resources>
        <ResourceDictionary>
            <local:IntegerGreaterThanOneToBoolConverter x:Key="IntegerGreaterThanOneToBoolConverter"/>
        </ResourceDictionary>
    </Application.Resources>

</Application>

Hope it helps.

Upvotes: 1

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