Datagrid Save: System.ArgumentNullException: Value cannot be null. (Parameter 'source')

Radzen.Blazor Components
1

Getting this exception after clicking the save button on a row edit. Everything else works fine.

Unhandled exception rendering component: Value cannot be null. (Parameter 'source')
System.ArgumentNullException: Value cannot be null. (Parameter 'source')
at System.Linq.ThrowHelper.ThrowArgumentNullException(ExceptionArgument argument)
at System.Linq.Enumerable.Where[TSource](IEnumerable1 source, Func2 predicate)
at Radzen.Blazor.RadzenDataGridRow`1.FindComponent(String name)
at Radzen.Blazor.ValidatorBase.ValidateField(Object sender, FieldChangedEventArgs args)
at Microsoft.AspNetCore.Components.Forms.EditContext.NotifyFieldChanged(FieldIdentifier& fieldIdentifier)
at Radzen.Blazor.RadzenTextBox.OnChange(ChangeEventArgs args)
at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion(Task task)
at Microsoft.AspNetCore.Components.RenderTree.Renderer.GetErrorHandledTask(Task taskToHandle)
fail: Microsoft.AspNetCore.Components.Server.Circuits.CircuitHost[111]
Unhandled exception in circuit 'Jct-lE32zXC570pYsDg1zKWyjiON6Q5sDidqPXn0Knk'.

@page "/Platforms"
@using TpsPortalWeb.Data.Models
@using TpsPortalWeb.Data.Services

@inject IPlatformService PlatformService
@inject NotificationService NotificationService
@inject DialogService DialogService

<RadzenFieldset>
<HeaderTemplate>
    <h3><RadzenIcon Icon="dns" /> Platforms</h3>
</HeaderTemplate>
<ChildContent>

    <RadzenDataGrid @ref="platformGrid" AllowFiltering="true" AllowColumnResize="true" FilterMode="FilterMode.Simple" PageSize="25" AllowPaging="true" AllowSorting="true" Data="@Platforms" TItem="Platform" LogicalFilterOperator="LogicalFilterOperator.Or" EditMode="DataGridEditMode.Single">
        <Columns>
            <RadzenDataGridColumn TItem="Platform" Property="PlatformId" Filterable="false" Title="ID" Frozen="true" TextAlign="TextAlign.Center" Width="100px" />
            <RadzenDataGridColumn TItem="Platform" Property="Name" Title="Name">
                <EditTemplate Context="platform">
                    <RadzenTextBox @bind-Value="platform.Name" Name="Name" />
                    <RadzenRequiredValidator Text="Name is required" Component="Name" Popup="true" />
                </EditTemplate>
            </RadzenDataGridColumn>
            <RadzenDataGridColumn TItem="Platform" Context="platform" Filterable="false" Sortable="false" TextAlign="TextAlign.Center" Width="100px">
                <Template Context="platform">
                    <RadzenButton Icon="edit" Size="ButtonSize.Medium" Click="@(args => EditRow(platform))" @onclick:stopPropagation="true">
                    </RadzenButton>
                </Template>
                <EditTemplate Context="platform">
                    <RadzenButton Icon="save" Size="ButtonSize.Medium" Click="@((args) => SavePlatform(platform.PlatformId, platform.Name))">
                    </RadzenButton>
                    <RadzenButton Icon="cancel" Size="ButtonSize.Medium" ButtonStyle="ButtonStyle.Secondary" Click="@((args) => CancelChanges(platform))">
                    </RadzenButton>
                </EditTemplate>
            </RadzenDataGridColumn>
            <RadzenDataGridColumn TItem="Platform" Context="platform" Filterable="false" Sortable="false" TextAlign="TextAlign.Center" Width="70px">
                <Template Context="platform">
                    <RadzenButton ButtonStyle="ButtonStyle.Danger" Icon="close" Size="ButtonSize.Medium" Click="@(args => DeletePlatform(platform.PlatformId))" @onclick:stopPropagation="true">
                    </RadzenButton>
                </Template>
            </RadzenDataGridColumn>

        </Columns>
    </RadzenDataGrid>
</ChildContent>
</RadzenFieldset>

<RadzenFieldset>
<HeaderTemplate>
    <h3><RadzenIcon Icon="note_add" /> Create Platform</h3>
</HeaderTemplate>
<ChildContent>
    <div class="row">
        <label for="createName">Name: </label>
        <RadzenTextBox Placeholder="Platform..." Name="Name" MaxLength="50" @bind-Value="@createName" />
        <RadzenLengthValidator Component="Name" Min="3" Text="Name should be at least 3 characters" Popup=@popup Style="position: absolute" />

        <RadzenButton ButtonType="ButtonType.Submit" Text="Submit" Click=@(args => CreatePlatform())></RadzenButton>
    </div>
</ChildContent>
</RadzenFieldset>

@code {
    RadzenDataGrid<Platform> platformGrid = new RadzenDataGrid<Platform>();
    string createName = string.Empty;
    List<Platform> Platforms = new List<Platform>();
    bool popup;

protected override async Task OnInitializedAsync()
{
    try
    {
        await GetPlatforms();
        base.OnInitialized();
    }
    catch (Exception e)
    {
        ShowNotification(new NotificationMessage { Severity = NotificationSeverity.Error, Summary = "Error Loading Page", Detail = e.Message, Duration = 10000 });
    }
}

async Task GetPlatforms()
{
    Platforms = await PlatformService.GetPlatforms();
}

async Task DeletePlatform(int PlatformId)
{
    var response = await DialogService.Confirm("Are you sure you want to Delete this?", "Delete Platform?", new ConfirmOptions() { OkButtonText = "Yes", CancelButtonText = "No" }) ?? false;

    if (response)
    {
        var result = await PlatformService.DeletePlatform(PlatformId);
        ShowNotification(new NotificationMessage { Severity = NotificationSeverity.Info, Summary = "Deleting Platform Result", Detail = result, Duration = 5000 });
        await GetPlatforms();
    }
}

async Task CreatePlatform()
{
    var result = await PlatformService.CreatePlatform(createName);
    ShowNotification(new NotificationMessage { Severity = NotificationSeverity.Info, Summary = "Creating Platform Result", Detail = result, Duration = 5000 });
    createName = string.Empty;
    await GetPlatforms();
}

void ShowNotification(NotificationMessage message)
{
    NotificationService.Notify(message);
}

void EditRow(Platform platform)
{
    platformGrid.EditRow(platform);
}

async Task SavePlatform(int platFormId, string name)
{
    var result = await PlatformService.UpdatePlatform(platFormId, name);
    ShowNotification(new NotificationMessage { Severity = NotificationSeverity.Info, Summary = "Edit Platform Result", Detail = result, Duration = 5000 });
    await GetPlatforms();
}

void CancelChanges(Platform platform)
{
    platformGrid.CancelEditRow(platform);
}
}
2

You might need to get reference to the grid instead creating new instance.

3

Isn't that being done by

<RadzenDataGrid @ref="platformGrid"

or is there another way to do it?

4

What’s the purpose of this code?

5

Doesn't appear to do anything, I added it just to see if there was an instantiation issue. I still the error with it or just RadzenDataGrid platformGrid;

6

For example, if you declare

IQueryable<LookupModel> orders;

And inside your Radzen component you call for example an IQueryable like this:

@orders.Count()

It will throw an error.

The solution is in your code make the list accept to be null:

IQueryable<LookupModel>? orders;
@orders?.Count()