Hello,

I have a similar problem with XamDataGrid and  IDataErrorInfo support for TemplateField.

It highlights the error on the name but not on subjects. Can you please advise ?

Thanks

<dP:XamDataGrid   DataSource="{Binding Path=Students}">

<dP:XamDataGrid.FieldLayoutSettings>
                <dP:FieldLayoutSettings SupportDataErrorInfo="RecordsAndCells" DataErrorDisplayMode="ErrorIconAndHighlight"/>
</dP:XamDataGrid.FieldLayoutSettings>

<dP:XamDataGrid.FieldLayouts>
                <dP:FieldLayout>
				<dP:Field Name="Name"/>
				<dP:TemplateField Name="Subjects" BindingType="UseAlternateBinding" AlternateBinding="{Binding Subjects}" Width="Auto">
                        <dP:TemplateField.DisplayTemplate>
                            <DataTemplate>
                                <ig:XamComboEditor Style="{StaticResource ComboBoxInCellStyle}"
                                                   MaxWidth="150"
                                                   AllowMultipleSelection="True"
                                                   CheckBoxVisibility="Visible"
                                                   ItemsSource="{Binding Path=AllSubjects}"
                                                   SelectedItems="{Binding ., Mode=TwoWay,UpdateSourceTrigger=PropertyChanged,NotifyOnSourceUpdated=True,NotifyOnTargetUpdated=True}"
                                                   DisplayMemberPath="Label" >
                                </ig:XamComboEditor>
                            </DataTemplate>
                        </dP:TemplateField.DisplayTemplate>
                    </dP:TemplateField>
                </dP:FieldLayout>
</dP:XamDataGrid.FieldLayouts>
</dP:XamDataGrid>

public class Student : IDataErrorInfo, INotifyPropertyChanged
    {
	public string Name {
	get{return name;}
	set{
	name = value;
	OnPropertyChanged();
	}
	}
	
	public ObservableCollection<string> Subjects {
	get;
	set;
	}
	
	public string this[string columnName]
        {
            get
            {
                if (columnName == nameof(Name))
                {
                    if (string.IsNullOrEmpty(Name))
                    {
                        return "Name cannot be empty";
                    }
                }
                if (columnName == nameof(Subjects))
                {
                    if (Subjects == null || !Subjects.Any())
                    {
                        return "Subjects cannot be empty";
                    }
                }
                return string.Empty;
            }
        }

        public string Error { get { return string.Empty; } }
	
	}