MVC模型在帖子上为空
[英]MVC Model is null on post
问题描述
My viewmodel works fine on GET, but on post it is null and I cannot understand why. 
我的viewmodel在GET上运行正常，但在帖子上它是null，我无法理解为什么。 Any help would be greatly appreciated. 任何帮助将不胜感激。 The Quiz-post doesn't do much at this stage, I need to access the posted model before I can finish the method. 测验帖在这个阶段做得不多，我需要在完成方法之前访问已发布的模型。 The repository.GetAllQuestionsList() returns a list of QuizViewModel repository.GetAllQuestionsList（）返回QuizViewModel列表
ViewModel 视图模型
public class QuizViewModel {
public int Id { get; set; }
public int QuestionId { get; set; }
public string QuestionText { get; set; }
public int QuestionNbr { get; set; }
public int CurrentQuestion { get; set; }
public int TotalNbrOfQuestions { get; set; }
public List<Answer> Answers { get; set; }
}
Controller 调节器
public ActionResult Quiz() {
var getAllQuestions = repository.GetAllQuestionsList();
var model = getAllQuestions.Where(c => c.QuestionNbr == 1);
Session["CurrentQ"] = 1;
return View(model);
}
[HttpPost]
public ActionResult Quiz(IEnumerable<Models.QuizViewModel> model) {
int question = Convert.ToInt32(Session["CurrentQ"]);
string str = Request.Params["btnSubmit"];
if (str == "Next Question") {
question++;
Session["CurrentQ"] = question;
}
if (str == "Prev Question") {
question--;
Session["CurrentQ"] = question;
}
return View(model);
}
View 视图
@model IEnumerable<Quiz.Models.QuizViewModel>
@{
Layout = null;
}
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width"/>
<title>Quiz</title>
</head>
<body>
<p>
@Html.ActionLink("Create New", "Create")
</p>
@using (Html.BeginForm()) {
<table class="table">
<tr>
<th>
@Html.DisplayNameFor(model => model.QuestionText)
</th>
<th>
@Html.DisplayNameFor(model => model.QuestionNbr)
</th>
<th>
answer
</th>
<th></th>
</tr>
@foreach (var item in Model) {
<tr>
<td>
@Html.DisplayFor(modelItem => item.QuestionText)
</td>
<td>
@Html.DisplayFor(modelItem => item.QuestionNbr)
</td>
<td>
@foreach (var ML in item.Answers) {
@Html.RadioButtonFor(model => item.Answers, ML.Id)
@Html.Label(ML.AnswerText)
<br/>
}
</td>
</tr>
}
</table>
<input type="submit" id="Submit1" name="btnSubmit" value="Prev Question"/>
<input type="submit" id="Submit2" name="btnSubmit" value="Next Question"/>
}
</body>
</html>
2 个解决方案
解决方案1
2 已采纳 2015-10-28 17:30:08
I dont't think your code will work ever as the name binding are not generated properly also @Html.DisplayNameFor(model => model.QuestionText) and @Html.DisplayNameFor(model => model.QuestionNbr) will throw exception as Model is of type IEnumerable. 我不认为你的代码会工作，因为名称绑定也没有正确生成@Html.DisplayNameFor(model => model.QuestionText)和@Html.DisplayNameFor(model => model.QuestionNbr)将抛出异常，因为Model是IEnumerable类型。 HttpPost binding works only if the name are input controls are generated appropriately in generated html when posted to server. 只有当名称是输入控件时，HttpPost绑定才能在生成的html中生成，当发布到服务器时。 I have corrected your code.Please refer the below 我已经更正了你的代码。请参阅下面的内容
@{
Layout = null;
}
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width"/>
<title>Quiz</title>
</head>
<body>
<p>
@Html.ActionLink("Create New", "Create")
</p>
@using (Html.BeginForm()) {
<table class="table">
<tr>
<th>
@Html.DisplayNameFor(model => model[0].QuestionText)
</th>
<th>
@Html.DisplayNameFor(model => model[0].QuestionNbr)
</th>
<th>
answer
</th>
<th></th>
</tr>
@for (int index = 0; index > Model.Count; index++) {
<tr>
<td>
@Html.DisplayFor(modelItem => modelItem[index].QuestionText)
</td>
<td>
@Html.DisplayFor(modelItem => modelItem[index].QuestionNbr)
</td>
<td>
@for (int jIndex = 0; jIndex < Model[index].Answers; jIndex++ ) {
@Html.RadioButtonFor(model => modelItem[index].Answers[jIndex].Answer, modelItem[index].Answers[jIndex].Id)
@Html.Label(modelItem[index].Answers[jIndex].AnswerText)
<br/>
}
</td>
</tr>
}
</table>
<input type="submit" id="Submit1" name="btnSubmit" value="Prev Question"/>
<input type="submit" id="Submit2" name="btnSubmit" value="Next Question"/>
}
</body>
</html>
解决方案2
1 2015-10-28 16:41:55
Ignoring the @Html.DisplayNameFor(model => model.QuestionText) which (as I said doesn't make sense). 忽略@Html.DisplayNameFor(model => model.QuestionText) （正如我所说的那样没有意义）。 You just need to change you iterator so that it knows where in the array the item lives, ie 您只需要更改迭代器，以便它知道项目在数组中的位置，即
@for (int i = 0; i < Model.Count; i++) {
<tr>
<td>
@Html.DisplayFor(modelItem => modelItem[i].QuestionText)
</td>
<td>
@Html.DisplayFor(modelItem => modelItem[i].QuestionNbr)
</td>
..... etc
}
foreach doesn't work very well in an MVC view because the HTML helper doesn't know where in the array it is and the names aren't built up correctly. foreach在MVC视图中不能很好地工作，因为HTML帮助程序不知道它在数组中的位置，并且名称没有正确构建。
声明:本站的技术帖子网页，遵循CC BY-SA 4.0协议，如果您需要转载，请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.