I have a custom component which takes RenderFragment and displays it as ChildContent. I'm passing TelerikForm for ChildContent and getting such error: Unhandled exception rendering component: Specified cast is not valid.
Here's the custom component:
<div class="gg_wizard_step @(IndexInParent != ParentSection.CurrentStep ? "hidden" : "")">
<CascadingValue Value="this">
@ChildContent
</CascadingValue>
</div>
@code {
[Parameter]
public RenderFragment ChildContent { get; set; }
[CascadingParameter]
public NLWizardSection ParentSection { get; set; }
[Parameter]
public int IndexInParent { get; set; }
protected override void OnInitialized()
{
base.OnInitialized();
ParentSection.AddChild(this);
}
}
Here's the form added to custom component:
<NLWizardStep>
<h3>@L["What is the name of your resource?"]</h3>
<TelerikForm Model="@((NameForm)_currentForm)"
@ref="NameFormRef"
ValidationMessageType="FormValidationMessageType.Inline">
<FormValidation>
<DataAnnotationsValidator></DataAnnotationsValidator>
<CustomValidation></CustomValidation>
</FormValidation>
<FormItems>
<FormItem Field="@nameof(NameForm.Name)"></FormItem>
</FormItems>
<FormButtons></FormButtons>
</TelerikForm>
</NLWizardStep>1 Answer, 1 is accepted
Hi Akmal,
It seems like the error "Specified cast is not valid" might be occurring due to a casting issue with the Model property of the TelerikForm within your custom component. Here are a few things to check and try:
Ensure the Model Type Matches: Double-check that _currentForm is indeed of type NameForm at runtime. This error can occur if _currentForm is not the expected type when the form tries to cast it.
Cascading Parameters: Since you are using CascadingValue, ensure that all necessary parameters are correctly passed down to the TelerikForm. If there's a mismatch or an incorrect type being cascaded, it could lead to casting issues.
Blazor Component Restrictions: Blazor sometimes has specific restrictions or behaviors around rendering fragments and component hierarchies. Make sure that the TelerikForm is compatible with being used within a CascadingValue component. You might want to try a simple test by placing the TelerikForm outside of any custom component to see if it renders without issues. You may also test with an EditForm instead of a TelerikForm to validate if you get the same behavior.
If after checking these points the issue persists, I recommend isolating the problem by gradually reducing the complexity of the form or custom component until you identify the specific cause.
Regards,
Nadezhda Tacheva
Progress Telerik