Xamarin Forms: Binding: Property "" Not Found on ""

Question

Good day: I am having issues getting binding on a collectionview datatemplate.

<ContentPage
    x:Class="MyBloodSugar.Views.ReadingsPage"
    xmlns="http://xamarin.com/schemas/2014/forms"
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
    xmlns:viewmodel="clr-namespace:MyBloodSugar.ViewModels"
    x:DataType="viewmodel:ReadingsViewModel">

    <ContentPage.BindingContext>
        <viewmodel:ReadingsViewModel />
    </ContentPage.BindingContext>

    <StackLayout>
        <CollectionView ItemsSource="{Binding Readings}" SelectionMode="Single">
            <CollectionView.ItemTemplate>
                <DataTemplate>
                    <Grid
                        Padding="10"
                        ColumnDefinitions="Auto,*"
                        RowDefinitions="Auto, *">

                        <Label
                            Grid.Column="1"
                            FontAttributes="Bold"
                            Text="{Binding TimeOfDay}" />
                        <Label
                            Grid.Row="1"
                            Grid.Column="1"
                            FontAttributes="Bold"
                            Text="{Binding Weight}" />
                    </Grid>
                </DataTemplate>
            </CollectionView.ItemTemplate>
        </CollectionView>
    </StackLayout>
</ContentPage>

In my viewmodel

 public ObservableRangeCollection<MyReading> Readings { get; private set; }

My Model

public class MyReading
    {
        public DateTime TimeOfDay { get; set; }
        public float Glocouse { get; set; }
        public int Dia { get; set; }
        public int Sys { get; set; }
        public float Weight { get; set; }

        public override string ToString()
        {
            return Glocouse.ToString();
        }

    }

Can you help me understand what I am doing wrong?

Thanks in advance.

Answer 1

Hello,​

Welcome to our Microsoft Q&A platform!

ObservableRangeCollection is a thrid-part nuget-packages, I do not use it, I use System.Collections.ObjectModel.ObservableCollection to replace it, Here is running screenshot, I can get running normally without error.

Here is my ReadingsViewModel.cs.

   using System.Collections.ObjectModel;  
   using System.Text;  
     
   namespace App26  
   {  
       public  class ReadingsViewModel  
       {  
           public ObservableCollection<MyReading> Readings { get; private set; }  
     
            
           public ReadingsViewModel()  
           {  
               Readings = new ObservableCollection<MyReading>();  
     
               Readings.Add(new MyReading() { Dia=  1, Sys=2,   Weight=0.2f, Glocouse=0.3f, TimeOfDay=DateTime.Now });  
               Readings.Add(new MyReading() { Dia = 2, Sys = 2, Weight = 0.2f, Glocouse = 0.3f, TimeOfDay = DateTime.Now });  
               Readings.Add(new MyReading() { Dia = 3, Sys = 2, Weight = 0.2f, Glocouse = 0.3f, TimeOfDay = DateTime.Now });  
               Readings.Add(new MyReading() { Dia = 4, Sys = 2, Weight = 0.2f, Glocouse = 0.3f, TimeOfDay = DateTime.Now });  
               Readings.Add(new MyReading() { Dia = 5, Sys = 2, Weight = 0.2f, Glocouse = 0.3f, TimeOfDay = DateTime.Now });  
           }  
     
     
       }  
     
       public class MyReading  
       {  
           public DateTime TimeOfDay { get; set; }  
           public float Glocouse { get; set; }  
           public int Dia { get; set; }  
           public int Sys { get; set; }  
           public float Weight { get; set; }  
     
           public override string ToString()  
           {  
               return Glocouse.ToString();  
           }  
     
       }  
   }  

I do not use x:DataType="viewmodel:ReadingsViewModel" in your layout.

   <ContentPage xmlns="http://xamarin.com/schemas/2014/forms"  
                xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:viewmodel="clr-namespace:App26"  
                x:Class="App26.Page1">  
       <ContentPage.BindingContext>  
           <viewmodel:ReadingsViewModel />  
       </ContentPage.BindingContext>  
     
       <StackLayout>  
           <CollectionView ItemsSource="{Binding Readings}" SelectionMode="Single">  
               <CollectionView.ItemTemplate>  
                   <DataTemplate>  
                       <Grid  
                            Padding="10"  
                            ColumnDefinitions="Auto,*"  
                            RowDefinitions="Auto, *">  
     
                           <Label  
                                Grid.Column="1"  
                                FontAttributes="Bold"  
                                Text="{Binding TimeOfDay}" />  
                           <Label  
                                Grid.Row="1"  
                                Grid.Column="1"  
                                FontAttributes="Bold"  
                                Text="{Binding Weight}" />  
                       </Grid>  
                   </DataTemplate>  
               </CollectionView.ItemTemplate>  
           </CollectionView>  
       </StackLayout>  
   </ContentPage>  

Best Regards,

Leon Lu

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Answer 2

Hi
I know its already commented as an answer but I would like to add my 50 cent

<CollectionView ItemsSource="{Binding Readings}" SelectionMode="Single">
             <CollectionView.ItemTemplate>
                 <DataTemplate>

in DataTemplate you should have to define the data type so the compiler know where to find the items

like this :

<DataTemplate x:DataType="viewmodels:Emptydesck">
                <ImageCell Text="{Binding IDEmptydesck}"
                           Detail="{Binding roomNu}" />

            </DataTemplate>

while viewmodels:Emptydesck is refer to

 public class Emptydesck
    {
        public string IDEmptydesck { get; set; }
        public string roomNu { get; set; }
    }