查看返回 Model 作为 Null 到 Controller

Question

晚上好，我正在尝试创建一个包含多个提交 forms 的视图​​，一个工作正常，另一个抛出 null 异常错误。 我究竟做错了什么？

看法

<div class="modal" tabindex="-1" role="dialog" id="jobModal">
<div class="modal-dialog modal-lg" role="document">
    <div class="modal-content">
        <div class="modal-header">
            <h5 class="modal-title">Confirm Selected Job</h5>
            <button type="button" class="close" data-dismiss="modal" aria-label="Close">
                <span aria-hidden="true">&times;</span>
            </button>
        </div>
        <div class="modal-body" id="jobModalBodyDiv"style="font-size: 1.05rem;">
            <p style="text-align:center"><b>Are you sure you want to sign-up this mass/service?</b></p>
            <p style="text-align:center"><b>Note: By clicking Accept Job, you are agreeing to perform at the mass/service specified above.</b></p>
            <div class="modal-footer" style="bottom: 0; width: 100%; height: 60px; justify-content: center">
                @using (Html.BeginForm("SignUpForJob", "App", FormMethod.Post))
                {
                    <input type="text" name="jobID" value="@Model.job.id" />
                    <button type="submit" class="btn btn-primary">Accept Job</button>
                    <button type="button" class="btn btn-secondary" data-dismiss="modal">Cancel</button>
                }
            </div>
        </div>
    </div>
</div>

<div class="modal" tabindex="-2" role="dialog" id="removeMassModal">
    <div class="modal-dialog modal-lg" role="document">
        <div class="modal-content">
            <div class="modal-header">
                <h5 class="modal-title">Confirm Job Cancellation</h5>
                <button type="button" class="close" data-dismiss="modal" aria-label="Close">
                    <span aria-hidden="true">&times;</span>
                </button>
            </div>
            <div class="modal-body" id="removeMassModalBodyDiv" style="font-size: 1.05rem;">
                <p style="text-align:center"><b>You are trying to cancel the following job:</b></p>
                <table id="cancelInfo">
                    <tbody>

                        <tr>
                            <td>Date</td>
                            <td>@Model.job.MassDateTime.ToLongDateString()</td>
                        </tr>

                        <tr>
                            <td>Time</td>
                            <td>@Model.job.MassDateTime.ToShortTimeString()</td>
                        </tr>

                        <tr>
                            <td>Mass Type</td>
                            <td>@Model.job.MassType</td>
                        </tr>

                        <tr>
                            <td>Language</td>
                            <td>@Model.job.Language</td>
                        </tr>

                        <tr>
                            <td>Musician Type</td>
                            <td>@Model.job.MusicianType</td>
                        </tr>







                    </tbody>
                </table>
                @using (Html.BeginForm("CancelJob", "App", FormMethod.Post))
                {
                    <label for="cancellationReason">Please enter a reason for your cancellation:</label>
                    @Html.TextBoxFor(m => m.cancelled.cancellationReason)
                    <p style="text-align:center"><b>Note: Cancellations are monitored. Abusing this will result in your account being banned!</b></p>
                    <div class="modal-footer" style="bottom: 0; width: 100%; height: 60px; justify-content: center">
                        <input type="text" name="jobID" value="@Model.jobID" />
                        <input type="submit" class="btn btn-primary" value="Cancel Job" />
                        <button type="button" class="btn btn-secondary" data-dismiss="modal">Cancel</button>

                    </div>
                }
            </div>
        </div>
    </div>
</div>

Model

public class ViewJobModel
{
    public SubJobs job { get; set; }
    public JobCancellation cancelled { get; set; }
}

Controller

 public ActionResult ViewJob(int jobID)
    {
        //take out of production app
        //jobID = 1;
        ViewJobModel viewJob = new ViewJobModel();
        ApplicationDbContext db = new ApplicationDbContext();
        var job = db.SubJobs.Where(x => x.id == jobID).SingleOrDefault();
        
        var church = db.Churches.Where(x => x.churchID == job.ChurchID).First();
        SubJobs jobDetails = new SubJobs();
        jobDetails.MassDateTime = job.MassDateTime;
        jobDetails.MassDateTime = job.MassDateTime;
        jobDetails.ChName = job.ChName;
        jobDetails.ChDenomination = job.ChDenomination;
        jobDetails.ChType = job.ChType;
        jobDetails.ChCity = job.ChCity;
        jobDetails.ChState = job.ChState; 
        jobDetails.id = job.id;
        jobDetails.Language = job.Language;
        jobDetails.Stipend = job.Stipend;
        int musicianTypeID = Convert.ToInt32(job.MusicianType);
        string musicianType = db.MusicianTypes.Find(musicianTypeID).TypeName;
        jobDetails.MusicianType = musicianType;
        int masstypeid = Convert.ToInt32(job.MassType);
        string massType = db.MassTypes.Find(masstypeid).MassType;
        jobDetails.MassType = massType;
        jobDetails.ChPhone = church.Phone;
        jobDetails.ChZip = church.Zip;
        jobDetails.ChAddress = church.Address;
        jobDetails.Notes = job.Notes;
        jobDetails.PersonCreated = job.PersonCreated;
        jobDetails.PersonCreatedID = job.PersonCreatedID;
        jobDetails.PersonSelected = job.PersonSelected;
        jobDetails.PersonSelectedID = job.PersonSelectedID;
        int month = jobDetails.MassDateTime.Month;
        ViewBag.day = jobDetails.MassDateTime.Day;
  
        switch(month)
        {
            case 1:
                ViewBag.month = "Jan";
                break;
            case 2:
                ViewBag.month = "Feb";
                break;
            case 3:
                ViewBag.month = "Mar";
                break;
            case 4:
                ViewBag.month = "Apr";
                break;
            case 5:
                ViewBag.month = "May";
                break;
            case 6:
                ViewBag.month = "Jun";
                break;
            case 7:
                ViewBag.month = "Jul";
                break;
            case 8:
                ViewBag.month = "Aug";
                break;
            case 9:
                ViewBag.month = "Sep";
                break;
            case 10:
                ViewBag.month = "Oct";
                break;
            case 11:
                ViewBag.month = "Nov";
                break;
            case 12:
                ViewBag.month = "Dec";
                break;
        }
        jobDetails.Created = job.Created;
        jobDetails.Description = job.Description;
        jobDetails.Requirements = job.Requirements;
        ApplicationUser user = userManager.FindById(job.PersonCreatedID);
        ViewBag.hometown = user.HomeTown;
        viewJob.job = jobDetails;    
        
        return View(viewJob);
    }
    [HttpPost]
    public ActionResult SignUpForJob(int jobID)
    {
       
        if (jobID > 0)
        {
            ApplicationDbContext db = new ApplicationDbContext();
            var userId = User.Identity.GetUserId();
            var job = db.SubJobs.Find(jobID);
            ApplicationUser user = userManager.FindById(userId);
            var person = user.FullName;
            job.PersonSelected = person;
            job.PersonSelectedID = userId;
            db.SaveChanges();
            TempData["Success"] = "You have successfully agreed to perform at a mass/service on " + job.MassDateTime.ToLongDateString() + " at " + job.MassDateTime.ToShortTimeString();
            return RedirectToAction("SubJobs", "App");
        }
        TempData["Failed"] = "An error occured when trying to assign to you the mass that was selected";
        return RedirectToAction("SubJobs", "App");
    }

    [HttpPost]
    public ActionResult CancelJob(ViewJobModel vjm)
    {
        if (ModelState.IsValid)
        {
            if (vjm.jobID > 0)
            {
                ApplicationDbContext db = new ApplicationDbContext();
                var userId = User.Identity.GetUserId();
                ApplicationUser user = userManager.FindById(userId);
                var job = db.SubJobs.Find(vjm.job.id);
                JobCancellation cancelledJob = new JobCancellation();
                cancelledJob.cancellationDate = DateTime.Now;
                cancelledJob.cancellationReason = vjm.cancelled.cancellationReason;
                cancelledJob.jobID = vjm.job.id;
                cancelledJob.userID = userId;
                db.JobCancellation.Add(cancelledJob);
                TempData["Success"] = "You have successfully cancelled a mass/service on " + job.MassDateTime.ToLongDateString() + " at " + job.MassDateTime.ToShortTimeString();
                db.SaveChanges();
                return RedirectToAction("SubJobs", "App");
            }
            TempData["Failed"] = "An error occured when trying to cancel the mass that was selected";
            return RedirectToAction("SubJobs", "App");
        }
        return View(vjm);
    }

问题是，当我使用 SignUpForJob 表单时它工作正常，但是当我使用 CancelJob 时，controller 会引发 null 引用异常。 所有字段都由 SubJobs model 填充，但是当我汇总表单时出现错误。 View Job 是具有两种模式的主页，一个是 SignUpForJob，另一个是 CancelJob。

谢谢你的帮助。