Hide row if data is empty in ListView - xaml

Question

How can I remove the row Comment is on if its null or empty string?
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="30*" />
<ColumnDefinition Width="50*" />
</Grid.ColumnDefinitions>
<Label Text="{Binding EntryDate}" Grid.Column="0" Grid.Row="0"></Label>
<Label Text="{Binding Sleep}" Grid.Column="1" Grid.Row="0"></Label>
<Label Text="{Binding Comment}" Grid.Column="0" Grid.ColumnSpan="4"
Grid.Row="1"></Label>
</Grid>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>

Answer 1

This is the appropriate case to use a ValueConverter.
All you need to do is create a converter like this:
namespace App.Converters
{
public class TextToBoolConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if(value != null)
if (!(value is string)) return true;
return string.IsNullOrWhiteSpace(value as string) ? false : true;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
}
And use it on the IsVisible property of Label:
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:converters="clr-namespace:App.Converters"
x:Class="App.Views.SamplePage">
<ContentPage.Resources>
<ResourceDictionary>
<converters:TextToBoolConverter x:Key="TextToBoolConverter" />
</ResourceDictionary>
</ContentPage.Resources>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="30*" />
<ColumnDefinition Width="50*" />
</Grid.ColumnDefinitions>
<Label Text="{Binding EntryDate}" Grid.Column="0" Grid.Row="0"></Label>
<Label Text="{Binding Sleep}" Grid.Column="1" Grid.Row="0"></Label>
<Label Text="{Binding Comment}" Grid.Column="0" Grid.ColumnSpan="4"
Grid.Row="1"
IsVisible={Binding Comment, Converter={StaticResource TextToBoolConverter}}/>
</Grid>
</ContentPage>
Thus you can reuse it wherever you need.

Answer 2

Your model:
public class MyModel
{
//...other properties ...
public string Comment { get; set; }
public bool HasComment => !string.IsNullOrEmpty(Comment);
}
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="30*" />
<ColumnDefinition Width="50*" />
</Grid.ColumnDefinitions>
<Label Text="{Binding EntryDate}" Grid.Column="0" Grid.Row="0"></Label>
<Label Text="{Binding Sleep}" Grid.Column="1" Grid.Row="0"></Label>
<Label Text="{Binding Comment}" Grid.Column="0" Grid.ColumnSpan="4"
Grid.Row="1" IsVisible = {Binding HasComment}></Label>
</Grid>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>