Blazor ObjectGraphDataAnnotationsValidator issue - validation

Question

I am using ObjectGraphDataAnnotationsValidator and ValidateComplexType to validate form.
After the focus out from InputText, the validation reports an error regardless of whether the field is filled in correctly.
invalid form
When I validate form with EditContext.Validate(), validation works as expected.
valid form
InputText binds Name property from dto object:
(For testing purposes, I have set the identifiers to the classes.)
public class TestDto
{
private string _name;
public string InstanceId { get; private set; }
public string ViewModelInstanceId { get; private set; }
Required(ErrorMessage = "Name fieild is required.")]
public string Name
{
// after focus out event on InputText, first call of this getter is from old empty (new) instance created on OnInitialized
// ViewModelInstanceId is always the same, as expected
get => _name;
set => _name = value;
}
public TestDto(string viewModelInstanceId)
{
ViewModelInstanceId = viewModelInstanceId;
InstanceId = Guid.NewGuid().ToString();
}
}
My razor page
<EditForm EditContext="EditContext">
<ObjectGraphDataAnnotationsValidator />
<ValidationSummary />
<p>
<InputText #bind-Value="ViewModel.TestDto.Name" />
<ValidationMessage For="()=>ViewModel.TestDto.Name" />
</p>
<p>
<button #onclick="()=>ViewModel.ValidateForm?.Invoke()">Validate form</button>
</p>
</EditForm>
#code{
protected EditContext EditContext { get; set; } = null!;
[ValidateComplexType]
protected TestViewModel ViewModel { get; private set; } = null!;
protected override void OnInitialized()
{
ViewModel = new TestViewModel();
//If this line is removed, everything works as expected
ViewModel.TestDto = new TestDto(ViewModel.InstanceIdId) //Instance1
{
Name = string.Empty//this makes validation to fail because it is required field
};
ViewModel.ValidateForm = () => EditContext.Validate();
EditContext = new EditContext(ViewModel);//Validates form as expected
base.OnInitialized();
}
protected override void OnAfterRender(bool firstRender)
{
if(firstRender){
ViewModel.LoadTestDto();//Instance2
StateHasChanged();
}
base.OnAfterRender(firstRender);
}
}
View model
public class TestViewModel
{
public string InstanceId { get; private set; }
public string PageTitle => "Test page";
public Func<bool> ValidateForm { get; set; }
[ValidateComplexType]
public TestDto TestDto { get; set; }
public TestViewModel()
=> InstanceId = Guid.NewGuid().ToString();
public void LoadTestDto()
{
TestDto = new TestDto(InstanceId)//Instance2
{
Name = "Loaded name"
};
}
}
So, I have decide to test TestDto.Name getter and setter.
After focus out from InputText, those were hitted breakpoints on Name getter and setter:
Name setter => setted new entered value to Instance2 (created on OnAfterRender)
Name getter => returns empty value from Instance1 ?!? (created on OnInitialized)
Name getter => returns new entered value from Instance2 (created on OnAfterRender)
...
Any ideas? I am brainwashed :D and probably overlooked something :/
P.S. In case when TestDto instance is setted only during OnAfterRendering event, everything works as expected, but that isn't desired scenario.
EDIT:
Why am I creating empty instance of TestDto on OnInitialized?
Because I can not set #bind-Value of nullable object.
Something like this:
<InputText #bind-Value="ViewModel?.TestDto?.Name" />
I know I can hide form like:
#if(ViewModel.TestDto != null)
{
<InputText #bind-Value="ViewModel.TestDto.Name" />
}
but I want to show empty form before data is loaded.

Answer 1

Reassigning EditContext after new TestDto instance is setted to TestViewModel.TestDto property fixes all..
So, on TestViewModel.TestDto setter I had to invoke method from razor base class to reassign EditContext property
TestViewModel
[ValidateComplexType]
public TestDto TestDto
{
get => _testDto;
set
{
testDto= value;
ReassignEditContext?.Invoke();
}
}
Razor.cs
private void ReassignEditContext()
=> EditContext = new EditContext(TestViewModel);
I just can't believe that is right way to do it...
Does anyone have better idea?
Similar test project can be found on https://github.com/CashPJ/EditFormValidationTest