ASP.NET MVC 5组单选按钮

Question

我正在开始我的第一个ASP.NET MVC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,因此单选按钮应按名称属性分组(对于每个问题,一组单选按钮).但是这段代码只生成一个组,所以当我回答第二个问题时,首先会取消选择.我需要改变什么？

编辑
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的一个实例中,我保存了一个学生和他应该回答的所有问题(一般和他正在研究的科目相关)并将其传递给查看.在视图中,我将所有问题都以单一形式提出,它们都是无线电的类型.那么,任何人都可以帮我分组单选按钮并正确回发此表单吗？

Answer 1

您的代码存在许多问题,包括生成重复id的(无效的html),生成重复的name属性(这就是为什么您只创建一个组,但更重要的是,这会阻止您在发布时绑定到模型)无论如何,你实际上并没有绑定到有效的财产.

您需要创建视图模型来表示要显示和编辑的内容,并在for循环中生成单选按钮(或使用EditorTemplate),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" />
}

调节器

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
}

注意我对模型隐含的数据库结构感到有些困惑(例如,为什么需要单独的模型Question以及SubjectQuestion何时将null值SubjectID标识为"常规"问题).我建议你首先在GET方法中对一些值进行硬编码,看看它是如何工作的,然后回发.

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
    }
  }
};

发布时,模型将填充每个主题中每个问题的所选答案的ID.请注意DisplayFor()某些属性的用法.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,您可以生成只读文本框或为这些属性添加隐藏输入.我还建议你检查生成的HTML,特别是看起来像的名称属性

<input type="radio" name="Subjects[0].Questions[0].SelectedAnswer" ...

让您了解集合如何在回发后绑定到您的模型

Answer 2

诀窍是使用一个表达式(Html.RadioButtonFor的第一个参数),它包含一组每个单选按钮更改的值.在您的情况下,它将是问题列表中的索引.

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,这里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; }
}

这是动作方法的代码:

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"}
                    }
            },
        }
});