How to bind nested listview within listitem of parent list, after applying grouping? - xaml

Question

How to bind nested listview within listitem of parent list.
I followed below posts, and now need help to bind ItemSource of a nested listview present within listitem data template.
https://montemagno.com/enhancing-xamarin-forms-listview-with-grouping/
how to bind list inside litview in xamarin.forms
Some thing like below-
Group Header 1
Item 1
Listitem 1
Listitem 2
Item 2
Listitem 1
Listitem 2
Group Header 2
Item 1
Listitem 1
Item 2
Listitem 1
Listitem 2
Listitem 3
My Code-
<ContentPage.Content>
<StackLayout Spacing="0">
<StackLayout HeightRequest="5" HorizontalOptions="CenterAndExpand" BackgroundColor="{StaticResource Key=primary-back-title-color}">
<Label HeightRequest="5" WidthRequest="800" HorizontalOptions="FillAndExpand" BackgroundColor="{StaticResource Key=primary-back-title-color}" />
</StackLayout>
<StackLayout HeightRequest="40" BackgroundColor="{StaticResource Key=page-name-background-color}" Orientation="Vertical">
<Label VerticalOptions="CenterAndExpand" Margin="10,0,0,0" FontAttributes="Bold" TextColor="White" Text="My Cart" />
</StackLayout>
<ListView ItemsSource="{Binding VendorProduct}" HasUnevenRows="true" SeparatorVisibility="None" SelectedItem="none" IsGroupingEnabled="true" x:Name="CartProductListView" ItemSelected="Handle_ItemSelected">
<ListView.GroupHeaderTemplate>
<DataTemplate>
<ViewCell Height="20">
<Grid BackgroundColor="White" HeightRequest="25" Margin="0,0,0,5">
<Label Margin="10,1,0,1" FontSize="14" VerticalOptions="CenterAndExpand" FontAttributes="Bold" TextColor="{StaticResource Key=page-name-background-color}" Text="{Binding VendorName}">
</Label>
</Grid>
</ViewCell>
</DataTemplate>
</ListView.GroupHeaderTemplate>
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<StackLayout>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="15" />
<RowDefinition Height="15" />
</Grid.RowDefinitions>
<StackLayout Margin="5,0,0,0" Grid.Row="0" Orientation="Horizontal">
<Label FontSize="14" Text="DC-Customer Name: ">
</Label>
<Label FontSize="14" TextColor="#AD2C2C" Text="ABC-123456">
</Label>
</StackLayout>
<StackLayout Margin="5,0,0,0" Grid.Row="1" Orientation="Horizontal">
<Label FontSize="14" Text="Zone Price: ">
</Label>
<Label FontSize="14" TextColor="#AD2C2C" Text="$4.21">
</Label>
</StackLayout>
</Grid>
<Grid Margin="10,10,0,0" ColumnSpacing="0">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="Auto" />
</Grid.ColumnDefinitions>
<RelativeLayout HeightRequest="94" Grid.Column="0" WidthRequest="{Binding DealsHeight}">
<ListView ItemsSource="{Binding Deals}" Rotation="270" RelativeLayout.XConstraint="{ConstraintExpression Type=RelativeToParent,Property=Width,Factor=0.5,Constant=-47}" RelativeLayout.YConstraint="{ConstraintExpression Type=RelativeToParent,Property=Width,Factor=-0.5,Constant=47}" RelativeLayout.WidthConstraint="{ConstraintExpression Type=Constant,Constant=94}" RelativeLayout.HeightConstraint="{ConstraintExpression Type=RelativeToParent,Property=Width,Factor=1}" RowHeight="94" SeparatorVisibility="None" HasUnevenRows="true" BackgroundColor="White">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<ViewCell.View>
<Grid BackgroundColor="#BCD153" RowSpacing="1" Padding="1" Rotation="90" HeightRequest="94">
<Grid.RowDefinitions>
<RowDefinition Height="30" />
<RowDefinition Height="30" />
<RowDefinition Height="30" />
</Grid.RowDefinitions>
<StackLayout BackgroundColor="White" Grid.Row="0" Padding="5">
<Label Text="{Binding BookCode}" FontSize="13" />
</StackLayout>
<StackLayout BackgroundColor="White" Grid.Row="1" Padding="5">
<Label Text="{Binding Amount, StringFormat='${0} OFF'}" FontSize="13" />
</StackLayout>
<StackLayout BackgroundColor="White" Grid.Row="2">
<Entry Keyboard="Numeric" IsEnabled="{Binding IsQuantityEditable}" Text="{Binding Quantity}">
<Entry.Behaviors>
<converters:NumericMaxLengthBehavior x:Name="PhoneNumberValidator" />
</Entry.Behaviors>
</Entry>
</StackLayout>
</Grid>
</ViewCell.View>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</RelativeLayout>
<StackLayout Grid.Column="1">
<Label Text="Month" VerticalOptions="CenterAndExpand" TextColor="Silver" FontSize="12" HeightRequest="30" />
<Label Text="Discount" VerticalOptions="CenterAndExpand" TextColor="Silver" FontSize="12" HeightRequest="30" />
<Label Text="Quantity" VerticalOptions="CenterAndExpand" TextColor="Silver" FontSize="12" HeightRequest="30" />
</StackLayout>
</Grid>
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
<Button Margin="0,20,0,0" Text="Propose Order" Command="{Binding ShowOrdersCommand}" BackgroundColor="{StaticResource Key=primary-back-title-color}" TextColor="White" VerticalOptions="Center" HorizontalOptions="Center" WidthRequest="200">
</Button>
</StackLayout>
</ContentPage.Content>