动态MVC RadioButton组选择的答案

我有一个动态填充的问题和答案列表。

两个问题：

1. 回发后不显示问题和答案
2. 缺少所选答案

视图模型

public class RegistrationViewModel : RegisterExternalLoginModel { //...etc... public Question Question { get; set; } public Answer Answer { get; set; } public List Questions { get; set; } public IList PossibleAnswers { get; set; } public List SelectedAnswers { get; set; } public IList PreviousAnswers { set { foreach(Question q in Questions) { q.SelectedAnswers = value.Where(t => t.questionId == q.objectId).ToList() ; } } } } 

选定答案

  public Answer SelectedAnswer { get { if (SelectedAnswers != null && SelectedAnswers.Count > 0) { var answers = SelectedAnswers.Where(t => t.questionId == objectId); if (answers.Count() == 1) { var result = Answers.Where(t => t.objectId == answers.First().answerId).First(); return result; } } return null; } } 

的ActionResult

  public ActionResult CreateQuestions() { RegistrationViewModel vm = new RegistrationViewModel(); IQFacade facade = new QFacade(CreateUserContext(true)); //Questions and Answers vm.Questions = facade.GetQuestions().ToList(); vm.PossibleAnswers = facade.GetPossibleAnswers(); return View(vm); } 

岗位

  [HttpPost] public ActionResult CreateQuestions(RegistrationViewModel vm) { var context = CreateUserContext(true); try{ IQFacade f = new QFacade(context); f.CreateSomething(vm.User.name, vm.etc, vm.SelectedAnswers);//Need all the answers here, but null } catch (Exception ex) { //error stuff, etc... return View(vm);//the questions do not appear after this point. Do I need to bind them again from GetQuestions or shouldn't they still be a part of the vm object that I am returning? } } return RedirectToAction("Index"); } 

在视图中，我使用的是编辑器模板

  @Html.EditorFor(x => x.Questions) 

模板

  @foreach (var possibleAnswer in Model.Answers) { 
 @Html.RadioButtonFor(question => question.SelectedAnswer, possibleAnswer.objectId, new { id = possibleAnswer.objectId }) @possibleAnswer.text @possibleAnswer.value 
@possibleAnswer.description
 
 } 

一切都是第一次工作，但不是在回发之后。 我已经阅读了几十篇类似的SOpost。 我错过了什么？

Answer 1

根据评论，你的模型应该是这样的（不确定你所有的模型属性，所以我在这里做一些假设）

 public class QuestionVM { public int ID { get; set; } // for binding public string Text { get; set; } [Required] public int? SelectedAnswer { get; set; } // for binding public IEnumerable PossibleAnswers { get; set; } } public class RegistrationViewModel : RegisterExternalLoginModel { public RegistrationViewModel() { Questions = new List(); } //...etc... public List Questions { get; set; } } 

GET方法

 public ActionResult CreateQuestions() { RegistrationViewModel vm = new RegistrationViewModel(); ..... // Populate the questions and answers var questions = facade.GetQuestions().ToList(); var answers = facade.GetPossibleAnswers(); foreach (var question in questions) { QuestionVM qvm = new QuestionVM(); qvm.ID = question.ID; qvm.Test = question.Text; // Add possible answers for the question qvm.PossibleAnswers = answers.Where(a => a.QuestionID == question.ID); // If loading existing questions/answers for existing user, also set value of current SelectedAnswer so its selected by default in the view vm.Questions.Add(qvm); } return View(vm); } 

视图

 @model YourAssembly.RegistrationViewModel .... @for(int i = 0; i < Model.Questions.Count; i++) { @Html.HiddenFor(m > m.Questions[i].ID) // for binding @Html.DisplayFor(m > m.Questions[i].Text) foreach(var answer in Model.Questions[i].PossibleAnswers) { @Html.RadioButtonFor(m => m.Questions[i].SelectedAnswer, answer.ID, new { id = answer.ID}) answer.Text } } 

POST方法

 [HttpPost] public ActionResult CreateQuestions(RegistrationViewModel vm) { if (!ModelState.IsValid) { // You need to rebuild the question text and possible answers because these are not posted back return View(vm); } // Your model is now populated with the ID of each question and the selected answer which can be saved to the database 

请注意，您可以为问题和答案文本值添加隐藏的输入，以便它们回发，但通常在控制器中重新加载它的性能会更好（如果包含正确的数据注释并包括客户端validation，则模型应始终在回发时有效无论如何）