@using Blazored.FluentValidation @using FluentValidation <div style="margin: 150px auto; width: 50%"> <EditForm Model="@_annotation"> <FluentValidationValidator @ref="_testFluentValidationValidator" /> <InputText class="form-control" Value="@_annotation.Name" ValueChanged="ChangeValue" ValueExpression="@(() => _annotation.Name)"></InputText> <ValidationMessage For="@(() => _annotation.Name)" /> </EditForm> </div> @code { private FluentValidationValidator? _testFluentValidationValidator; private Annotation _annotation = new(); protected async Task ChangeValue(string newValue) { _annotation.Name = newValue; var result = (await _testFluentValidationValidator!.ValidateAsync(options => options.IncludeRuleSets("TestNames"))); if (result) { await Task.Delay(100); } else { await Task.Delay(100); } } public class AnnotationValidator : AbstractValidator<Annotation> { public AnnotationValidator() { RuleSet("TestNames", () => { RuleFor(e => e.Name) .NotEmpty().WithMessage("Please enter a name.") .MinimumLength(3).WithMessage($"Name must be longer than 2 characters."); }); } } public class Annotation { public string Name { get; set; } } }