ASP.NET MVC 5组单选按钮如何实现?

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我将开始我的第一个ASP.NETMVC项目,所以我有一个简单的问题。我有以下代码:

foreach(var question in Model.GeneralQuestions)
{
    <div class = "well">
        <h3>
            <strong>@question.QuestionString</strong>
        </h3>
        @foreach (var answer in question.PossibleAnswers)
        {
            @Html.RadioButtonFor(model => question.QuestionString, answer.Answer)
            @Html.Label(answer.Answer)
            <br />
        }
    </div>
}

Model.GeneralQuestions中的所有问题都是唯一的,所以单选按钮应该按名称属性分组(对于每个问题一组单选按钮)。但是这个代码只产生一个组,所以当我第一个回答第二个问题时就会取消选择。我需要改变什么? 我的模型看起来像:

public class StudentViewModel
{
    public Student Student { get; set; }
    public List<Question> GeneralQuestions { get; set; }
    public List<SubjectQuestions> SubjectQuestions { get; set; }
}
public class Student
{
    public int StudentID { get; set; }
    public string Index { get; set; }
    public string Name { get; set; }
    public string Surname { get; set; }

    public virtual ICollection<Subject> Subjects { get; set; }
}
public class Question
{
    public int QuestionID { get; set; }
    public string QuestionString { get; set; }
    public bool IsAssociatedWithSubject { get; set; }

    public virtual ICollection<PossibleAnswer> PossibleAnswers { get; set; }
    public virtual ICollection<Results> Results { get; set; }
}
public class SubjectQuestions
{
    public Subject Subject { get; set; }
    public List<Question> Questions { get; set; }
}
public class Results
{
    public int ResultsID { get; set; }
    public int QuestionID { get; set; }
    public int? SubjectID { get; set; }
    public int PossibleAnswerID { get; set; }

    public virtual Question Question { get; set; }
    public virtual PossibleAnswer PossibleAnswer { get; set; }
    public virtual Subject Subject { get; set; }
}

在StudentViewModel的一个例子中,我保存一个学生以及他应该回答的所有问题(包括一般情况和他正在学习的科目的相关内容)并将其传递给查看。鉴于我将所有问题都以单一形式提出,并且都是无线电广播。所以,任何人都可以帮助我分组单选按钮并正确回复此表单吗?

提问于
用户回答回答于

代码存在许多问题,包括生成重复id的(无效的html),生成重复的name属性(这就是为什么只创建一个组,但更重要的是,这会阻止您在回发时绑定到模型),而且你实际上并没有绑定到有效的属性。

将需要创建视图模型来表示要显示和编辑的内容,并在for循环(或使用EditorTemplate)中生成单选按钮,以便使用索引器正确命名它们。

查看模型

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<AnswerVM> PossibleAnswers { get; set; }
}

public class SubjectVM
{
  public int? ID { get; set; }
  [DisplayFormat(NullDisplayText = "General")]
  public string Name { get; set; }
  public List<QuestionVM> Questions { get; set; }
}

public class AnswerVM
{
  public int ID { get; set; }
  public string Text { get; set; }
}

public class StudentVM
{
  public int ID { get; set; }
  public string Name { get; set; }
  // plus any other properties of student that you want to display in the view
  public List<SubjectVM> Subjects { get; set; }
}

视图

@model YourAssembly.StudentVM
@using(Html.BeginForm())
{
  @Html.HiddenFor(m => m.ID)
  @Html.DisplayFor(m => m.Name)
  for(int i = 0; i < Model.Subjects.Count; i++)
  {
    @Html.HiddenFor(m => m.Subjects[i].ID)
    @Html.DisplayFor(m => m.Subjects[i].Name) // will display "General" if no name
    for (int j = 0; j < Model.Subjects[i].Questions.Count; j++)
    {
      @Html.HiddenFor(m => m.Subjects[i].Questions[j].ID)
      @Html.DisplayFor(m => m.Subjects[i].Questions[j].Text)
      foreach(var answer in Model.Subjects[i].Questions[j].PossibleAnswers )
      {
        <div>
          @Html.RadioButtonFor(m => m.Subjects[i].Questions[j].SelectedAnswer, answer.ID, new { id = answer.ID})
          <label for="@answer.ID">@answer.Text</label>
        </div>
      }
      @Html.ValidationMessageFor(m => m.Subjects[i].Questions[j].SelectedAnswer)
    }
  }
  <input type="submit" value="save" />
}

控制器

public ActionResult Edit(int ID)
{
  StudentVM model = new StudentVM();
  // populate your view model with values from the database
  return View(model);
}

[HttpPost]
public ActionResult Edit(StudentVM model)
{
  // save and redirect
}

注意我对你的模型所隐含的数据库结构有点困惑(例如,为什么你需要单独的模型Question以及SubjectQuestion何时将nullSubjectID标识为“常规”问题)。我建议你首先在GET方法中对某些值进行硬编码,以查看它是如何工作并回发的。

StudentVM model = new StudentVM();
model.ID = 1;
model.Name = "bambiinela";
model.Subjects = new List<SubjectVM>()
{
  new SubjectVM()
  {
    Questions = new List<QuestionVM>()
    {
      new QuestionVM()
      {
        ID = 1,
        Text = "Question 1",
        SelectedAnswer = ?, // set this if you want to preselect an option
        PossibleAnswers = new List<AnswerVM>()
        {
          new AnswerVM()
          {
            ID = 1,
            Text = "Answer A"
          },
          new AnswerVM()
          {
            ID = 1,
            Text = "Answer B"
          }
        }
      },
      new QuestionVM()
      {
        ID = 2,
        Text = "Question 2",
        PossibleAnswers = new List<AnswerVM>()
        {
          // similar to above
        }
      }
    }
  },
  new SubjectVM()
  {
    ID = 1,
    Name = "Math",
    Questions = new List<QuestionVM>()
    {
      // similar to above
    }
  }
};

当你发布时,模型将填入每个主题中每个问题的选定答案的ID。请注意DisplayFor()某些属性的使用。这些不会回发,因此如果您返回视图(例如ModelState无效),则需要重新填充这些属性。或者,可以为这些属性生成只读文本框或添加隐藏输入。我还建议你检查一下生成的HTML,特别是名称属性,看起来像这样

<input type="radio" name="Subjects[0].Questions[0].SelectedAnswer" ...
用户回答回答于

诀窍是使用一个表达式(Html.RadioButtonFor的第一个参数),其中包含一个值,每个单选按钮组都会改变一个值。就你而言,它将成为问题列表中的一个索引。

以下是一些示例代码:

 @for (int i = 0; i < Model.GeneralQuestions.Count; i++)
 {
     var question = Model.GeneralQuestions[i];
     @Html.Label(question.QuestionString)
     <br />
     foreach (var answer in question.PossibleAnswers)
     {
         @Html.RadioButtonFor(model => 
           Model.GeneralQuestions[i].SelectedAnswerId, answer.Id)
         @Html.Label(answer.Answer)
         <br />
     }
 }

这会产生以下HTML:

<label for="Q1">Q1</label>
<br />
<input id="GeneralQuestions_0__SelectedAnswerId" 
  name="GeneralQuestions[0].SelectedAnswerId" type="radio" value="1" />
<label for="A01">A01</label>
<br />
<input id="GeneralQuestions_0__SelectedAnswerId" 
  name="GeneralQuestions[0].SelectedAnswerId" type="radio" value="2" />
<label for="A02">A02</label>
<br />
<label for="Q2">Q2</label>
<br />
<input id="GeneralQuestions_1__SelectedAnswerId" 
  name="GeneralQuestions[1].SelectedAnswerId" type="radio" value="11" />
<label for="A11">A11</label>
<br />
<input id="GeneralQuestions_1__SelectedAnswerId" 
  name="GeneralQuestions[1].SelectedAnswerId" type="radio" value="12" />
<label for="A12">A12</label>
<br />

为了完整起见,下面是使用的模型的简化版本:

public class StudentViewModel
{
    public List<Question> GeneralQuestions { get; set; }
}

public class Question
{
    public int QuestionId { get; set; }
    public string QuestionString { get; set; }
    public ICollection<PossibleAnswer> PossibleAnswers { get; set; }
    public int SelectedAnswerId { get; set; }
}

public class PossibleAnswer
{
    public int Id { get; set; }
    public string Answer { get; set; }
}

下面是action方法的代码:

return View(new StudentViewModel
{
    GeneralQuestions =
        new List<Question>
        {
            new Question
            {
                QuestionString = "Q1",
                PossibleAnswers =
                    new[]
                    {
                        new PossibleAnswer {Id = 1, Answer = "A01"},
                        new PossibleAnswer {Id = 2, Answer = "A02"}
                    }
            },
            new Question
            {
                QuestionString = "Q2",
                PossibleAnswers =
                    new[]
                    {
                        new PossibleAnswer {Id = 11, Answer = "A11"},
                        new PossibleAnswer {Id = 12, Answer = "A12"}
                    }
            },
        }
});

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