Hi @masleshov,
You should pass the Item property somehow to the CustomComponent. I tested the following which seems to work as expected.
Form.razor:
<RadzenTemplateForm TItem="Model" Data=@model >
<TestValidator Model=@model />
</RadzenTemplateForm>
TestValidator.razor:
<RadzenTextBox Name="FirstName" @bind-Value=@Model.FirstName />
<RadzenRequiredValidator Component="FirstName" Text="FirstName is required"/>
@code {
[Parameter]
public RequiredValidatorConfig.Model Model { get; set; }
}