为什么我发布的剃刀页面模型中应该有很多列表项，但列表项却为零？

Question

当我获得具有相同模型的视图时，它包含 2 个问题，每个问题有 2 个答案选项。到目前为止一切顺利。

问题是，无论我选择什么答案选项，当我发布表单时，即使我的索引在检查生成的 HTML 时看起来正确，文本也会正确呈现，因此循环和索引应该可以工作，但我总是得到零个问题。我在输入上使用了 asp-for 来绑定属性。为什么我没有收到任何问题回复？

我搜索过类似的帖子，但我根本看不出我在做什么不同或错误的事情，所以我一定错过了一些东西。请帮忙！

这是重现问题的视图：

@model JobMediation.Api.Models.Onboarding.ViewModels.StartOnboardingOnlineTestModel

@{
    ViewData["Title"] = "Online-test!";
    Layout = "~/Views/Shared/_Layout.cshtml";
}

@using (Html.BeginForm("StartOnboardingOnlineTest", "Onboarding", Model, FormMethod.Post))
{
    <div>
        @for (var i = 0; i < Model.OnboardingTestQuestions.Count; i++)
        {
            <p>
                @(i + 1). @Model.OnboardingTestQuestions[i].QuestionText
            </p>

            @for (var j = 0; j < Model.OnboardingTestQuestions[i].OnboardingTestAnswerOptions.Count; j++)
            {
                <div>
                    <input type="radio" asp-for="@Model.OnboardingTestQuestions[i].SelectedAnswerOptionId" value="@Model.OnboardingTestQuestions[i].OnboardingTestAnswerOptions[j].AnswerOptionId">
                    <label><p>@(j + 1). @Model.OnboardingTestQuestions[i].OnboardingTestAnswerOptions[j].Text</p></label>
                </div>
            }

            <div style="display:none">
                questionId: <input hidden asp-for="@Model.OnboardingTestQuestions[i].QuestionId" type="text" required>
                questionText: <input hidden asp-for="@Model.OnboardingTestQuestions[i].QuestionText" type="text" required>
            </div>
        }

        <button>Send</button>
    </div>
}

我的视图模型：

using System.Collections.Generic;

namespace JobMediation.Api.Models.Onboarding.ViewModels
{
    public class StartOnboardingOnlineTestModel
    {
        public List<OnboardingTestQuestion> OnboardingTestQuestions { get; set; } = new List<OnboardingTestQuestion>();
    }
}

using System.Collections.Generic;

namespace JobMediation.Api.Models.Onboarding.ViewModels
{
    public class OnboardingTestQuestion
    {
        public string QuestionId{ get; set; }
        public string QuestionText { get; set; }
        public List<OnboardingTestAnswerOption> OnboardingTestAnswerOptions { get; set; } = new List<OnboardingTestAnswerOption>();
        public string SelectedAnswerOptionId { get; set; }
    }
}

namespace JobMediation.Api.Models.Onboarding.ViewModels
{
    public class OnboardingTestAnswerOption
    {
        public string AnswerOptionId { get; set; }
        public string Text { get; set; }
    }
}

我的控制器：

[HttpGet]
[Route("/route")]
[CanBeLoggedInAttribute]
public async Task<IActionResult> StartOnboardingOnlineTest()
{
        var model = new StartOnboardingOnlineTestModel
        {
            OnboardingTestQuestions = new List<OnboardingTestQuestion> {
                new Models.Onboarding.ViewModels.OnboardingTestQuestion
                {
                    QuestionId = Guid.NewGuid().ToString(),
                    QuestionText = "Question 1",
                    OnboardingTestAnswerOptions = new List<OnboardingTestAnswerOption>
                    {
                        new Models.Onboarding.ViewModels.OnboardingTestAnswerOption
                        {
                            AnswerOptionId = Guid.NewGuid().ToString(),
                            Text = "Option 1"
                        },
                        new Models.Onboarding.ViewModels.OnboardingTestAnswerOption
                        {
                            AnswerOptionId = Guid.NewGuid().ToString(),
                            Text = "Option 2"
                        }
                    },
                    SelectedAnswerOptionId = Guid.Empty.ToString()
                },
                new Models.Onboarding.ViewModels.OnboardingTestQuestion
                {
                    QuestionId = Guid.NewGuid().ToString(),
                    QuestionText = "Question 2",
                    OnboardingTestAnswerOptions = new List<OnboardingTestAnswerOption>
                    {
                        new Models.Onboarding.ViewModels.OnboardingTestAnswerOption
                        {
                            AnswerOptionId = Guid.NewGuid().ToString(),
                            Text = "Option A"
                        },
                        new Models.Onboarding.ViewModels.OnboardingTestAnswerOption
                        {
                            AnswerOptionId = Guid.NewGuid().ToString(),
                            Text = "Option B"
                        }
                    },
                    SelectedAnswerOptionId = Guid.Empty.ToString()
                }
            }
        };

        return View("TEMP", model);
}

[HttpPost]
[Route("/route")]
public async Task<IActionResult> StartOnboardingOnlineTest(StartOnboardingOnlineTestModel model)
{
       // Handle the returned questions, but when debugging the model-parameter returns an empty list as model.OnboardingTestQuestions, see picture below
}

来自调试返回的 OnboardingTestQuestions 空列表的图片：

在此输入图片描述

我已经在谷歌上搜索过类似的帖子，但据我所知，我已经根据它们实施了。我使用 for 循环而不是 foreach，索引看起来正确，我使用 asp-for 和 HTML 输入来获取返回的数据，但没有成功。

例如我检查了这篇文章，为什么我的绑定列表使用 foreach 循环在 razor 页面上显示值返回空？，等等，我认为我已经做了同样的事情，但我的代码仍然无法工作。我还尝试过在 OnboardingTestQuestions 列表上使用和不使用 [BindProperty] 以及在 StartOnboardingOnlineTestModel 类上使用 [BindProperties]，没有任何区别。我还尝试过使用或不使用 OnboardingTestQuestions-list 和 OnboardingTestAnswerOption.-list 中的列表实例，也得到相同的结果。

GET 工作完美。 视图看起来符合预期。 当我在视图中查看问题和答案选项的索引时，它们就可以工作，并且我还通过右键单击并选择检查来检查生成的 HTML - 但显然有些东西仍然无法工作。下面是生成的 HTML 表单：

<form action="/soot?OnboardingTestQuestions=JobMediation.Api.Models.Onboarding.ViewModels.OnboardingTestQuestion&amp;OnboardingTestQuestions=JobMediation.Api.Models.Onboarding.ViewModels.OnboardingTestQuestion" method="post">    <div>
            <p>
                1. Question 1
            </p>
                <div>
                    <input type="radio" value="1dd8ff8d-fcaa-4a7d-b10f-e7c41bdd8c11" id="OnboardingTestQuestions_0__SelectedAnswerOptionId" name="OnboardingTestQuestions[0].SelectedAnswerOptionId">
                    <label><p>1. Option 1</p></label>
                </div>
                <div>
                    <input type="radio" value="37c6c1d3-40af-4fc0-a171-4546413c59f0" id="OnboardingTestQuestions_0__SelectedAnswerOptionId" name="OnboardingTestQuestions[0].SelectedAnswerOptionId">
                    <label><p>2. Option 2</p></label>
                </div>
            <div style="display:none">
                <br>questionId: <input hidden="" type="text" required="" id="OnboardingTestQuestions_0__QuestionId" name="OnboardingTestQuestions[0].QuestionId" value="c90d42ff-a67e-42e2-9ef1-e61ad64f783f">
                <br>questionText: <input hidden="" type="text" required="" id="OnboardingTestQuestions_0__QuestionText" name="OnboardingTestQuestions[0].QuestionText" value="Question 1">
            </div>
            <p>
                2. Question 2
            </p>
                <div>
                    <input type="radio" value="a9021d17-86d5-4d08-a36a-eeb88661a756" id="OnboardingTestQuestions_1__SelectedAnswerOptionId" name="OnboardingTestQuestions[1].SelectedAnswerOptionId">
                    <label><p>1. Option A</p></label>
                </div>
                <div>
                    <input type="radio" value="9ed4e62c-2a7c-42d8-a2b6-6e97d2d07806" id="OnboardingTestQuestions_1__SelectedAnswerOptionId" name="OnboardingTestQuestions[1].SelectedAnswerOptionId">
                    <label><p>2. Option B</p></label>
                </div>
            <div style="display:none">
                <br>questionId: <input hidden="" type="text" required="" id="OnboardingTestQuestions_1__QuestionId" name="OnboardingTestQuestions[1].QuestionId" value="0b420127-bfde-4a77-b109-683c4395da27">
                <br>questionText: <input hidden="" type="text" required="" id="OnboardingTestQuestions_1__QuestionText" name="OnboardingTestQuestions[1].QuestionText" value="Question 2">
            </div>

        <button>Send</button>
    </div>
<input name="__RequestVerificationToken" type="hidden" value="CfDJ8AnsrMzqwIVDvpNxYQXCuLVEqQaff31nYTXBVOW9EkiqYNmFWZHDGA2PfVBLPbbw_FTkHwn5ZsC7zmr1s8lYvxiXRwcCyVTOY4Lq2rbMfasFP4K_5XXEvY2TlqOOGFDUwpj1GHU1X7ZmRIDqHEh3UvU"></form>

POST 不会回复任何问题。为什么？我缺少什么？请帮忙！

Answer 1

使用下面的代码可以解决这个问题，这是测试结果。

@model JobMediation.Models.StartOnboardingOnlineTestModel

@{
    ViewData["Title"] = "Online-test!";
}

@using (Html.BeginForm("StartOnboardingOnlineTest", "Onboarding", FormMethod.Post))
{
    <div>
        @for (var i = 0; i < Model.OnboardingTestQuestions.Count; i++)
        {
            <p>@(i + 1). @Model.OnboardingTestQuestions[i].QuestionText</p>

            @for (var j = 0; j < Model.OnboardingTestQuestions[i].OnboardingTestAnswerOptions.Count; j++)
            {
                <div>
                    <input type="radio" asp-for="@Model.OnboardingTestQuestions[i].SelectedAnswerOptionId" value="@Model.OnboardingTestQuestions[i].OnboardingTestAnswerOptions[j].AnswerOptionId" />
                    <label>@(j + 1). @Model.OnboardingTestQuestions[i].OnboardingTestAnswerOptions[j].Text</label>
                </div>
            }

            <div style="display:none">
                <input hidden asp-for="@Model.OnboardingTestQuestions[i].QuestionId" type="text" required />
                <input hidden asp-for="@Model.OnboardingTestQuestions[i].QuestionText" type="text" required />
            </div>
        }

        <button>Send</button>
    </div>
}