RadzenDropDown does not change EditContext

Radzen.Blazor Components
1

I need to check if the form has changes.
For this, I use RadzenTemplateForm<>.EditContext property, which works fine for inputs like RadzenTextBox, but doesn't work for RadzenDropDown.
EditContext becomes "modified" only when RadzenDropDown changes at least two times, which seems to be a bug within RadzenDropDown.
Please, check the difference in the behavior in the small demo below:

<RadzenTemplateForm @ref="_form" Data="@_person">
  <RadzenLabel Text="Name" /><RadzenTextBox @bind-Value="@_person.Name" Style="width: 100%;" />
  <RadzenLabel Text="Country" /><RadzenDropDown @bind-Value="@_person.Country" Data="@_countries" Style="width: 100%;" />
  <RadzenButton Text="Save" Disabled="@(!HasChanges())" />
</RadzenTemplateForm>

@code {
  class Person
  {
    public string Name { get; set; }
    public string Country { get; set; }
  }

  private RadzenTemplateForm<Person> _form;
  private readonly Person _person = new();
  private readonly IEnumerable<string> _countries = new List<string> { "USA", "Germany" };

  private bool HasChanges()
  {
    return _form.EditContext.IsModified();
  }
}

Please advise.

2

For some reason the state of the page in this case is one step behind - not sure why however. Our DropDown component will execute EditContext.NotifyFieldChanged() in the same way as in our TextBox. For example when you select for the first time Country, IsModified() will return false however after second selection will return true - you can execute StateHasChanged() for the page in the DropDown Change event to avoid this:

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image1920×1080 233 KB

3

Is the issue here because DropDownBase.cs contains an EventDelegate for SelectedItemChanged, but does not seem to trigger the ValueChanged delegate?

Does that mean that ValueChanged is not being triggered up to the parent element?

4

Ignore me, I see you use ValueChanged under the raiseChanges condition.