[Bug] Null reference on validator even when manually setting Validator="new Validator()"

I’m getting a null reference on the validator for some strange reason, I have another form that uses the exact same method of validating. The validator for this form and the other are in the exact same place. The other validator works fine, but this one throws a null reference:

Microsoft.AspNetCore.Components.WebAssembly.Rendering.WebAssemblyRenderer[100]
      Unhandled exception rendering component: Object reference not set to an instance of an object.
System.NullReferenceException: Object reference not set to an instance of an object.
   at KitchensPlus.Client.Components.Dialogs.AddEditCustomer.get_Validated() in D:\Work\KitchensPlus\Client\Components\Dialogs\AddEditCustomer.razor:line 111

<EditForm Model="@Model" OnValidSubmit="SubmitAsync">
<FluentValidationValidator @ref="@_validator" />

@code {
    private FluentValidationValidator _validator;
    private bool Validated => _validator.Validate(options => { options.IncludeAllRuleSets(); });
}

I’ve even tried setting the validator manually:

<FluentValidationValidator Validator="new AddEditCustomerCommandValidator()" @ref="@_validator" />

It still results in a null reference. Am I missing something here? It’s driving me crazy.

Screenshots

RegisterRequestValidator works fine, AddEditCustomerCommandValidator isn’t working

Hosting Model (is this issue happening with a certain hosting model?): Blazor WebAssembly

.NET 6.0.7 Latest preview version of Blazored.FluentValidation (tried non preview versions too)

[ScottKane]

@Sharaf-Mansour Thanks for the reply, That makes sense, not sure I like that one works and one doesn’t but it’s good to know the fix is simple. I’ve moved to just initialising the validator manually with my own component while I was waiting so at least everything is working now.

[Sharaf-Mansour]

TL;DR;

Do null Checking

    private FluentValidationValidator? _validator;
    private bool? Validated => _validator?.Validate(options => { options.IncludeAllRuleSets(); });

and for the razor

 <MudButton OnClick="SubmitAsync" DisableElevation Variant="Variant.Filled"
 Disabled='@(!Validated ?? false)' Color="Color.Secondary">@(Model.Id != 0 ? "Update" : "Save")</MudButton>

@ScottKane I tried your repo and here is the issue I think we need to address. Using @ref will trigger OnAfterRender. So of course the _validator will be null because it is not pre-initialized

    private FluentValidationValidator _validator;

You can understand more about how ref work in blazor here. https://blazor-university.com/javascript-interop/calling-javascript-from-dotnet/passing-html-element-references/ and here. https://docs.microsoft.com/en-us/aspnet/core/blazor/components/?view=aspnetcore-6.0#capture-references-to-components So as a workaround we just need to handle the Null with some logic Something more like this

    private FluentValidationValidator? _validator;
    private bool? Validated => _validator?.Validate(options => { options.IncludeAllRuleSets(); });

and for the razor

 <MudButton OnClick="SubmitAsync" DisableElevation Variant="Variant.Filled"
 Disabled='@(!Validated ?? false)' Color="Color.Secondary">@(Model.Id != 0 ? "Update" : "Save")</MudButton>

To understand it more do this.

 @(_validator is null)
<button class="btn" @onclick="()=>StateHasChanged()">ref</button>

Before you press on the refresh button it will say true. meaning that _validator is indeed null, If you call StateHasChanged the _validator will be initialized and so it will say false… And about why it is working fine with Register.razor file Simply call @(Validated) And it will trigger the same error.