如何修复MVC中daterange参数为非空DateTime类型的空值错误

点击模态框的保存按钮后无法完成数据保存，报错如下：

The parameters dictionary contains a null entry for parameter 'daterange' of non-nullable type 'System.DateTime' for method 'System.Web.Mvc.ActionResult Index(System.String, System.String, System.String, System.String, System.String, System.String, System.String, Int32, System.Web.HttpPostedFileBase, System.DateTime, System.String)' in 'TestWeb.Controllers.MainController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter

奇怪的是代码在其他电脑上能正常运行，本地清理浏览器、VS缓存，甚至重装VS都无法解决问题。

Controller代码 #

[HttpPost]
public ActionResult Index(string StoreCode, string Purpose, string Dept, string Request, string Type, string detals, string size, int QTY, HttpPostedFileBase Picture, DateTime daterange, string Remarks)
{

    using (DatawarehouseEntities db = new DatawarehouseEntities())
    {
        string add = db.Add_PRW_Entries(StoreCode, Purpose, Dept, Request, Type, detals, size, QTY, "", Convert.ToDateTime(daterange), Remarks).FirstOrDefault().ToString();

        string filename = Picture.FileName;
        string filepath = "";
        string piclink = "";

        piclink = "//local host link";
        filepath = Path.Combine(Server.MapPath("~/Images/" + add), filename);
        if (!Directory.Exists(Server.MapPath("~/Images/" + add)))
        {
            Directory.CreateDirectory(Server.MapPath("~/Images/" + add));//create folder if it doesnt exist
        }
        Picture.SaveAs(filepath);

        db.Update_PictureLink_PRW(int.Parse(add), piclink);
    }

    return RedirectToAction("Index", "Main");
}

Views代码 #

<form action="~/Main/Index" class="needs-validation" enctype="multipart/form-data" id="insertmain" method="post">
<div class="input-group mb-3">


</div>
<div id="additemmodal" class="modal fade">
    <div class="modal-dialog modal-lg">
        <div class="modal-content">
            <div class="modal-header" style="background-color:#2c3e50">

                <h2 style="color:white; text-align:center">Add Record</h2>
                <button type="button" class="close" data-bs-dismiss="modal">&times;</button>
            </div>
            <div class="modal-body row has-error">
                <div class="col-6 mb-3">
                    <div> <label>Request Type:</label></div>
                    <select id="RTYPE" name="RTYPE">
                        @foreach (var items in ViewBag.TYPE)
                        {
                            <option value="@items.Request_Name">@items.Request_Name</option>
                        }
                    </select>
                    <div> <label>Business Unit:</label></div>
                    <select id="StoreCode" name="StoreCode">
                        @foreach (var items in ViewBag.cbstore)
                        {
                            <option value="@items.STSHRT">@items.STSHRT - @items.STRNAM</option>
                        }
                    </select>
                    <div><label><label>Purpose:</label></label></div>
                    <input class="form-control" type="text" id="Purpose" name="Purpose" required />
                    <div><label><label>Department:</label></label></div>
                    <input class="form-control" type="text" id="Dept" name="Dept" required />
                    <div><label><label>Request:</label></label></div>
                    <input class="form-control" type="text" id="Request" name="Request" required />
                    <div><label><label>Type of Materials:</label></label></div>
                    <input class="form-control" type="text" id="Type" name="Type" required />




                    <div><label><label>Image:</label></label></div>
                    <input class="form-control" type="file" id="Picture" name="Picture" onchange="imagePreview()" required />


                </div>
                <div class="col-6 mb-3">
                    <div><label><label>Details needed in materials:</label></label></div>
                    <input class="form-control" type="text" id="detals" name="details" required />
                    <div><label><label>Size:</label></label></div>
                    <input class="form-control" type="text" id="size" name="size" required />
                    <div><label><label>Quantity:</label></label></div>
                    <input class="form-control" type="text" id="QTY" name="QTY" onkeypress="return isNumber(event);" required />

                    <div><label><label>Target Date:</label></label></div>
                    <input type="text" name="daterange" id="daterange" required />
                    <div class="form-group mb-2 imgdiv">
                        <label class="control-label col-md-2" for="StoreNumber">Image Preview</label>
                        <div class="col-md-10 imgprv">
                            <img id="imgPreview" src="" data-fancybox />
                        </div>
                    </div>
                </div>

                <div><label><label>Remarks:</label></label></div>
                <textarea class="form-control" id="Remarks" name="Remarks" style="margin-left:10px; width:90%;" required></textarea>


                <div class="row">
                    <div class="col-6 mb-3">

                    </div>
                    <div class="col-12 mb-3">
                        <button class="btn btn-success input-group-text" onclick="confirm()" type="button" id="submit" name="submit">Save</button>
                        <button type="submit" id="Save" style="display:none"></button>
                    </div>
                </div>
            </div>
        </div>
    </div>
</div>

1. 修复参数绑定不匹配问题 #

• 视图中"Details needed in materials"对应的输入框name="details"，但Controller参数是string detals，名称不一致会导致参数接收失败。将视图中的name="details"改为name="detals"，或者把Controller参数改为string details。
• 日期选择器提交的是字符串，不同电脑区域设置可能导致MVC无法自动解析为DateTime。将Controller中的DateTime daterange改为可空类型DateTime? daterange，或者手动指定格式解析：

  [HttpPost]
  public ActionResult Index(string StoreCode, string Purpose, string Dept, string Request, string Type, string detals, string size, int QTY, HttpPostedFileBase Picture, string daterange, string Remarks)
  {
      DateTime targetDate = DateTime.ParseExact(daterange, "yyyy-MM-dd", System.Globalization.CultureInfo.InvariantCulture);
      // 后续代码中替换daterange为targetDate
  }
  

2. 统一日期选择器输出格式 #

确保前端日期选择器（如daterangepicker）输出的日期格式和后端解析格式一致，比如统一使用yyyy-MM-dd。如果未初始化日期选择器，需限制用户输入标准格式的日期。

3. 修复表单提交逻辑 #

视图中的保存按钮是type="button"，依赖confirm()函数触发提交，需确保该函数正确执行表单提交：

function confirm() {
    const form = document.getElementById('insertmain');
    if (form.checkValidity()) {
        form.submit();
    } else {
        form.reportValidity();
    }
}

也可以直接将保存按钮改为type="submit"，去掉隐藏的提交按钮，简化逻辑。

4. 统一本地区域设置 #

本地区域日期格式可能和其他电脑不一致，导致MVC模型绑定失败。在Web.config中添加全局配置统一区域：

<configuration>
  <system.web>
    <globalization culture="en-US" uiCulture="en-US" />
  </system.web>
</configuration>

内容的提问来源于stack exchange，提问作者Weboshii