Cannot perform runtime binding on a null reference

Radzen Studio Blazor Server
1

I want to have a datagrid and a card with label under it with binded date like this https://blazor.radzen.com/master-detail

But then i try to put it in radzen, like this video - https://www.youtube.com/watch?v=C_nEw-BAzvY&t, there is no data binding to text area, and when i bind it with code as ${order.OrderID) i get cannot perform runtime binding on a null reference. I get it, that its because when i load the page, no row is selected in the datagrid. How can i get i to work, or to select the firs row of datagrid on default?

2

Hi @Stefan_Stefanov1,

You can set the Visible property of the Label to ${order != null}. The other thing you can try is the elvis operator ${order?.OrderID}.

3

No, i still have the same problem. Is there another way?

4

That should have worked. Can you post some screenshots that show your configuration?

5

I cant post more then one picture so here https://drive.google.com/open?id=1zPzzqGuFsoLIN-4TLXpaeTRaLS64-TjX

6

Does it work at runtime though?

7

nope, it compiles but it leaves blank page.
this is the massege in the console:

warn: Microsoft.AspNetCore.Components.Server.Circuits.RemoteRenderer[100]
Unhandled exception rendering component: Cannot perform runtime binding on a null reference
Microsoft.CSharp.RuntimeBinder.RuntimeBinderException: Cannot perform runtime binding on a null reference
at CallSite.Target(Closure , CallSite , Object )
at System.Dynamic.UpdateDelegates.UpdateAndExecute1[T0,TRet](CallSite site, T0 arg0)
at CoBg.Pages.?????.b__0_0(RenderTreeBuilder __builder2)
at Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder.AddContent(Int32 sequence, RenderFragment fragment)
at Radzen.Blazor.RadzenContent.BuildRenderTree(RenderTreeBuilder __builder)
at Microsoft.AspNetCore.Components.ComponentBase.<.ctor>b__6_0(RenderTreeBuilder builder)
at Microsoft.AspNetCore.Components.Rendering.ComponentState.RenderIntoBatch(RenderBatchBuilder batchBuilder, RenderFragment renderFragment)
at Microsoft.AspNetCore.Components.RenderTree.Renderer.RenderInExistingBatch(RenderQueueEntry renderQueueEntry)
at Microsoft.AspNetCore.Components.RenderTree.Renderer.ProcessRenderQueue()

dotnet: fail: Microsoft.AspNetCore.Components.Server.Circuits.CircuitHost[111]
Unhandled exception in circuit 'A5rQlVtQhLbba6PIUtqY_LHV-AsenIhD7sSyRsSMRsA'.
Microsoft.CSharp.RuntimeBinder.RuntimeBinderException: Cannot perform runtime binding on a null reference
at CallSite.Target(Closure , CallSite , Object )
at System.Dynamic.UpdateDelegates.UpdateAndExecute1[T0,TRet](CallSite site, T0 arg0)
at CoBg.Pages.?????.b__0_0(RenderTreeBuilder __builder2)
at Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder.AddContent(Int32 sequence, RenderFragment fragment)
at Radzen.Blazor.RadzenContent.BuildRenderTree(RenderTreeBuilder __builder)
at Microsoft.AspNetCore.Components.ComponentBase.<.ctor>b__6_0(RenderTreeBuilder builder)
at Microsoft.AspNetCore.Components.Rendering.ComponentState.RenderIntoBatch(RenderBatchBuilder batchBuilder, RenderFragment renderFragment)
at Microsoft.AspNetCore.Components.RenderTree.Renderer.RenderInExistingBatch(RenderQueueEntry renderQueueEntry)
at Microsoft.AspNetCore.Components.RenderTree.Renderer.ProcessRenderQueue()

8

I received an update to the program, but the problem persists. Is it possible to select the first line from the grid when loading the view? I tried this Datagrid programly select a line, but i doesnt work no more. Maybe FirstorDefault method? Or when generating datagrid to have it on default whit this function?

9

Our DataGrid with Form page template supports this out of the box. I suggest you try it.

10

Thenks for that. By looking at the code i figured it out. So the the name of the set property should be defied two times - on the page it self, and on the grid on select row. For example "Click". On the page value should be result.FirstOrDefault(), and most important - property type should load automaticaly - for me is Appname.Models.DatabaseofApp.TableFromDataBase. Then on the grid itself the set property on rowselect - property type should be changed from dynamic to the same as the one on the page. And now it works. For some reason dynamic is not working properly.