Using a Dropdown List in Grid's Popup for editing

[eleven]

I'm using Telerik Blazor's Grid to show a table. Currently this table contains a column that uses an id that references to a string in another table. Currently the Grid is able to show the string using the following:

<GridColumn Field=@nameof(EEOTrainingVM.TrainingType) Title="Testing">
                <EditorTemplate>
                    @{
                        if (context as EEOTrainingVM is not null)
                        {
                            Training = context as EEOTrainingVM;
                            <TelerikDropDownList Data="@Trainings"
                                             @bind-Value="@Training.TrainingType"
                                         TextField="@nameof(LUTRAINING.desc)"
                                         ValueField="@nameof(LUTRAINING.code)"
                                                          
                                         Width="100%">
                            </TelerikDropDownList>
                        }
                    }
                </EditorTemplate>
                <Template>
                    @{
                            int trainName = (context as EEOTrainingVM).TrainingType;
                            <text>@GetTrainingValue(trainName)</text>
                    }
                </Template>
            </GridColumn>

I'm running into an issue where when clicking on the Edit button in a row, to show the Edit popup,  an exception is thrown  -

stem.NullReferenceException: Object reference not set to an instance of an object.
   at Telerik.Blazor.Extensions.ObjectExtensions.IsEqualTo[T](Object object1, T object2)
   at Telerik.Blazor.Components.TelerikDropDownList`2.<MapSelectedItem>b__138_0(ListDataItem item)
   at System.Linq.Enumerable.TryGetFirst[TSource](IEnumerable`1 source, Func`2 predicate, Boolean& found)
   at System.Linq.Enumerable.FirstOrDefault[TSource](IEnumerable`1 source, Func`2 predicate)
   at Telerik.Blazor.Components.TelerikDropDownList`2.MapSelectedItem()
   at Telerik.Blazor.Components.TelerikDropDownList`2.OnParametersSetAsync()
   at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion(Task task)
   at Microsoft.AspNetCore.Components.ComponentBase.RunInitAndSetParametersAsync()
   at Telerik.Blazor.Components.Common.TelerikSelectBase`2.SetParametersAsync(ParameterView parameters)
l

and I'm not sure why. The GetTrainingValue helper method is as follows:

        public string GetTrainingValue(int trainingID)
        {
            LUTRAINING match = TrainingType.FirstOrDefault(t => t.LUTRAINING.code == trainingID);
            return match != null ? match.LUTRAINING.desc : "Unknown";
        }

 

[Svetoslav Dimitrov]

Hello Jenna,

If I understood correctly, you would like to achieve a Foreign Key column in the Telerik UI for Blazor Grid. If I am correct, you can check the Foreign Key Column knowledge-based article where you can find a code snippet together with explanations. 

Can you take a look at that knowledge-based article and see if it helps you resolve the issue?

Regards,
Svetoslav Dimitrov
Progress Telerik