使用Xamarin Forms在CollectionView中使用属性ItemTemplate“LoadTemplate不应为null”

Question

I'm stuck in this problem in first try to use xamarin forms.

I'm trying to set DataTemplateSelector for CollectionView in Xamarin forms but I get this error "LoadTemplate should not be null".

It working without problems if I used ListView.

this is my XAML Code :

 <ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:viewmodel="clr-namespace:JisrWallet.ViewModels" xmlns:common="clr-namespace:JisrWallet.Common" x:Class="JisrWallet.views.Layout.CardsPage" xmlns:views="clr-namespace:SuaveControls.Views;assembly=SuaveControls.FloatingActionButton" BackgroundColor="{StaticResource lightGray}"> <ContentPage.Resources> <ResourceDictionary> <common:IntColorToHexConverter x:Key="colorConverter"/> <common:PrefixValueConverter x:Key="prefixConverter"/> <DataTemplate x:Key="existCardTemplate"> <StackLayout Margin="2"> <Image Source="{Binding StoreImageUrl}" Aspect="AspectFill" HeightRequest="120" BackgroundColor="{Binding CardColor, Converter={StaticResource colorConverter}}"/> </StackLayout> </DataTemplate> <DataTemplate x:Key="newCardTemplate"> <StackLayout BackgroundColor="{Binding CardColor, Converter={StaticResource colorConverter}}"> <Label Text="{Binding CardName, Converter={StaticResource prefixConverter}, ConverterParameter=1}" HeightRequest="120" HorizontalOptions="Center" VerticalOptions="Center" VerticalTextAlignment="Center" TextColor="White"/> <Label Text="{Binding CardName}" FontAttributes="Bold" BackgroundColor="{Binding CardColor, Converter={StaticResource colorConverter}}" TextColor="{StaticResource whiteColor}" HorizontalTextAlignment="Center"/> <BoxView HeightRequest="2" BackgroundColor="White"/> </StackLayout> </DataTemplate> <common:CardItemTemplateSelector x:Key="cardItemTemplateSelector" ExistCardTemplate="{StaticResource existCardTemplate}" NewCardTemplate="{StaticResource newCardTemplate}"/> </ResourceDictionary> </ContentPage.Resources> <StackLayout> <StackLayout.BindingContext> <viewmodel:CardsViewModel/> </StackLayout.BindingContext> <CollectionView x:Name="collectionView" ItemsSource="{Binding Cards}" ItemTemplate="{StaticResource newCardTemplate}" SelectionMode="Single" SelectionChanged="CollectionView_SelectionChanged"> <CollectionView.ItemsLayout > <GridItemsLayout Orientation="Vertical" Span="2" /> </CollectionView.ItemsLayout> </CollectionView> <views:FloatingActionButton Image="ic_add_white" ButtonColor="{StaticResource AccentColor}" WidthRequest="56" HeightRequest="56" HorizontalOptions="End" VerticalOptions="CenterAndExpand" Margin="8" Clicked="FloatingActionButton_Clicked"/> </StackLayout> </ContentPage> 

I can't figure out the problem. Can anyone help me please ?

Answer 1

you define the DataTemplateSelector in your <ResourceDictionary>

<ResourceDictionary>
  ...
  <common:CardItemTemplateSelector x:Key="cardItemTemplateSelector"
                                             ExistCardTemplate="{StaticResource existCardTemplate}"
                                             NewCardTemplate="{StaticResource newCardTemplate}"/>
</ResourceDictionary>

you could use it in your CollectionView like this:

<CollectionView>
      ...
     ItemTemplate="{StaticResource cardItemTemplateSelector}"         
</CollectionView>

more info refer to link: DataTemplateSelector