@page "/" @using System.ComponentModel.DataAnnotations @using System.Linq.Expressions; @using System.Reflection; @implements IHasEditContext; <h1>Hello, world!</h1> <EditForm EditContext="this.EditContextRef"> <DataAnnotationsValidator></DataAnnotationsValidator> <div class="form-group"> <InputText @bind-Value="@this.FirstName" class="form-control" /> <ValidationMessage For="() => this.FirstName"></ValidationMessage> </div> <div class="form-group"> <input @bind-value="@this.MiddleName" class="form-control" /> <ValidationMessage For="() => this.MiddleName"></ValidationMessage> </div> <div class="form-group"> <input value="@this.LastName" class="form-control" @onchange="(CreateBinder2(this, () => this.LastName, this.LastName))" /> <ValidationMessage For="() => this.LastName"></ValidationMessage> </div> <input type="submit" value="Go" /> </EditForm> @code { protected override void OnInitialized() { base.OnInitialized(); EditContextRef = new EditContext(this); } //BasicFormValidator Form1Validator = new BasicFormValidator(); [Required] public String FirstName { get; set; } = "delete me and change focus to cause validation"; [Required] public String MiddleName { get; set; } = "delete me and change focus - no validation"; [Required] public String LastName { get; set; } = "delete me and change focus - validation but manually calling NotifyFieldChanged"; public EditContext EditContextRef { get; set; } public static EventCallback<ChangeEventArgs> CreateBinder2( IHasEditContext receiver, Expression<Func<string?>> propExpression, string existingValue, System.Globalization.CultureInfo? culture = null) { var fieldIdentifier = FieldIdentifier.Create(propExpression); Action<String> valueSetter = (string v) => { PropertyInfo prop = fieldIdentifier.Model.GetType().GetProperty(fieldIdentifier.FieldName, BindingFlags.Public | BindingFlags.Instance); prop.SetValue(fieldIdentifier.Model, v); receiver.EditContextRef.NotifyFieldChanged(fieldIdentifier); }; return EventCallback.Factory.CreateBinder<string>(receiver, valueSetter, existingValue, culture); } }