MainPage.xaml

<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:dx="http://schemas.devexpress.com/maui"
             xmlns:local="clr-namespace:ValidateFormEvent"
             xmlns:ios="clr-namespace:Microsoft.Maui.Controls.PlatformConfiguration.iOSSpecific;assembly=Microsoft.Maui.Controls"
             ios:Page.UseSafeArea="true"
             x:Class="ValidateFormEvent.MainPage">
    <ContentPage.BindingContext>
        <local:TestOrderRepository/>
    </ContentPage.BindingContext>

    <dx:DataGridView x:Name="grid" ItemsSource="{Binding Orders}" 
                      RowTapCommand="{Binding Source={RelativeSource Mode=Self}, Path=Commands.ShowDetailEditForm}"
                      DetailEditFormTemplate="{DataTemplate local:OrderEditForm}">
        <dx:DataGridView.Columns>
            <dx:TextColumn FieldName="Product.Name" Caption="Product" />
            <dx:NumberColumn FieldName="Product.UnitPrice" Caption="Price" DisplayFormat="C0"/>
            <dx:NumberColumn FieldName="Quantity" />
            <dx:NumberColumn FieldName="Total" 
                          UnboundType="Integer" UnboundExpression="[Quantity] * [Product.UnitPrice]" 
                          IsReadOnly="True" DisplayFormat="C0" />
            <dx:DateColumn FieldName="Date" DisplayFormat="d" />
            <dx:CheckBoxColumn FieldName="Shipped" />
        </dx:DataGridView.Columns>
    </dx:DataGridView>
</ContentPage>