C# 远程验证随机抛出；字典包含一个空条目；错误

当远程验证尝试检查数据库中是否已经存在值时，我遇到了这个非常恼人的错误：

参数字典包含“ADVWKSP.Controllers.CRMTItemsController”中方法“System.Web.Mvc.JsonResult doesgbsNumberList（Int32）”的不可为null类型“System.Int32”的参数“gbsNumber”的null条目。可选参数必须是引用类型、可为null的类型或声明为可选参数。 参数名称：参数

视图模型

public class CRMTItemViewModel
{
    public int Id { get; set; }

    [Required]
    [Display(Name = "Project Title")]
    [Remote("DoesProjectTitleExist", "CRMTItems", HttpMethod = "POST", 
        ErrorMessage = "Workspace for that project title already exists.")]
    public string ProjectTitle { get; set; }

    [Required]
    [Display(Name = "Project Stage")]
    public ProjectStage? ProjectStage { get; set; }

    [Required]
    [Display(Name = "CRMT Number")]
    [Remote("DoesCrmtNumberExist", "CRMTItems", HttpMethod = "POST",
        ErrorMessage = "Workspace for that CRMT number already exists.")]
    public int? CRMTNumber { get; set; }

    [Required]
    [Display(Name = "GBS Number")]
    [Remote("DoesGbSNumberExist", "CRMTItems", HttpMethod = "POST", 
        ErrorMessage = "Workspace for that GBS project number already exists.")]
    public int? GbSNumber { get; set; }

    public bool Confidential { get; set; }

    [Required]
    [Display(Name = "Project Managers")]
    public IEnumerable<string> SelectedTags { get; set; }
}

公共类CRMTItemViewModel
{
公共int Id{get；set；}
[必需]
[显示（Name=“项目标题”）]
[远程（“DoesProjectTitleExist”、“CRMTItems”，HttpMethod=“POST”，
ErrorMessage=“该项目标题的工作区已存在。”）]
公共字符串ProjectTitle{get；set；}
[必需]
[显示（Name=“项目阶段”）]
公共ProjectStage？ProjectStage{get；set；}
[必需]
[显示（Name=“CRMT编号”）]
[远程（“DoesCrmtNumberExist”、“CRMTItems”、HttpMethod=“POST”，
ErrorMessage=“该CRMT编号的工作区已存在。”）]
公共int？CRMTNumber{get；set；}
[必需]
[显示（Name=“GBS编号”）]
[远程（“DoesGbSNumberExist”、“CRMTItems”、HttpMethod=“POST”，
ErrorMessage=“该GBS项目编号的工作区已存在。”）]
公共int？GbSNumber{get；set；}
公共布尔机密{get；set；}
[必需]
[显示（Name=“项目经理”）]
公共IEnumerable SelectedTags{get；set；}
}

查看

@using (Ajax.BeginForm("Create", "CRMTItems", new AjaxOptions
    {
        HttpMethod = "Post",
        UpdateTargetId = "divToUpdate",
        OnBegin = "submitBegin",
        OnSuccess = "submitSuccess",
        OnFailure = "submitFailure",
        OnComplete = "submitComplete"

    }, new { @ID = "AjaxForm" }))
{
<div class="form-horizontal">
    <h4>New Project Workspace Form</h4>
    <hr />
    @Html.ValidationSummary(true, "", new { @class = "text-danger" })
    <div class="form-group">
        @Html.LabelFor(model => model.ProjectTitle, htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.ProjectTitle, new { htmlAttributes = new { @class = "form-control"} })
            @Html.ValidationMessageFor(model => model.ProjectTitle, "", new { @class = "text-danger" })
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.ProjectStage, htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EnumDropDownListFor(model => model.ProjectStage, new { @class = "form-control"})
            @Html.ValidationMessageFor(model => model.ProjectStage, "", new { @class = "text-danger" })
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.CRMTNumber, htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.CRMTNumber, new { htmlAttributes = new { @class = "form-control"} })
            @Html.ValidationMessageFor(model => model.CRMTNumber, "", new { @class = "text-danger" })
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.GbSNumber, htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.GbSNumber, new { htmlAttributes = new { @class = "form-control"} })
            @Html.ValidationMessageFor(model => model.GbSNumber, "", new { @class = "text-danger" })
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.Confidential, htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.CheckBoxFor(model => model.Confidential, new { @class = "form-control", @style = "height:17px;" })
            @Html.ValidationMessageFor(model => model.Confidential, "", new { @class = "text-danger" })
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => Model.SelectedTags, htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.HiddenFor(m => m.Id)
            @Html.ListBoxFor(m => m.SelectedTags, new SelectList(users, "UserName", "DisplayName"), new { @class = "teamSelecter", name = "states[]", multiple = "multiple", style = "display:none; width:100%;"})
            @Html.ValidationMessageFor(model => model.SelectedTags, "", new { @class = "text-danger" })
            <p id="pmWarning" class="text-danger" hidden>Please select one or more project managers</p>
        </div>
    </div>

    <br />
    <button id="formSubmit" class="btn btn-default btn-lg pull-right" type="submit" value="submit">Submit</button>
    <div class="loader pull-right" hidden></div>
</div>
}

@使用（Ajax.BeginForm（“创建”、“CRMTItems”、新的AjaxOptions
{
HttpMethod=“Post”，
UpdateTargetId=“divToUpdate”，
OnBegin=“submitBegin”，
OnSuccess=“submitSuccess”，
OnFailure=“submitFailure”，
OnComplete=“submitComplete”
}，新的{@ID=“AjaxForm”}）
{
新项目工作区表单

@Html.ValidationSummary（true，“，new{@class=“text danger”}）
@LabelFor（model=>model.ProjectTitle，htmlAttributes:new{@class=“controllabel col-md-2”}）
@EditorFor（model=>model.ProjectTitle，new{htmlAttributes=new{@class=“form control”}}）
@Html.ValidationMessageFor（model=>model.ProjectTitle，“，new{@class=“text danger”}）
@LabelFor（model=>model.ProjectStage，htmlAttributes:new{@class=“controllabel col-md-2”}）
@EnumDropDownListFor（model=>model.ProjectStage，新的{@class=“form control”}）
@Html.ValidationMessageFor（model=>model.ProjectStage，“，new{@class=“text danger”}）
@LabelFor（model=>model.CRMTNumber，htmlAttributes:new{@class=“controllabel col-md-2”}）
@EditorFor（model=>model.CRMTNumber，new{htmlAttributes=new{@class=“form control”}}）
@Html.ValidationMessageFor（model=>model.CRMTNumber，“，new{@class=“text danger”}）
@LabelFor（model=>model.GbSNumber，htmlAttributes:new{@class=“controllabel col-md-2”}）
@EditorFor（model=>model.GbSNumber，new{htmlAttributes=new{@class=“form control”}}）
@Html.ValidationMessageFor（model=>model.GbSNumber，“，new{@class=“text danger”}）
@LabelFor（model=>model.Confidential，htmlAttributes:new{@class=“controllabel col-md-2”}）
@CheckBoxFor（model=>model.Confidential，新的{@class=“formcontrol”，@style=“height:17px；”}）
@Html.ValidationMessageFor（model=>model.Confidential，“，new{@class=“text danger”}）
@LabelFor（model=>model.SelectedTags，htmlAttributes:new{@class=“controllabel col-md-2”}）
@Html.HiddenFor（m=>m.Id）
@Html.ListBoxFor（m=>m.SelectedTags，new SelectList（用户，“用户名”，“显示名称”），new{@class=“teamselector”，name=“states[]”，multiple=“multiple”，style=“显示：无；宽度：100%；”）
@Html.ValidationMessageFor（model=>model.SelectedTags，“，new{@class=“text danger”}）
请选择一个或多个项目经理


提交
}

我将参数类型更改为

int？

，从那以后就再也没有看到错误，因此希望这一问题得到解决，但我们会看到的

更新控制器：

[HttpPost]
public JsonResult DoesGbSNumberExist(int? gbsNumber)
{
    using (var db = new ADVWKSPEntities())
    {
        return (gbsNumber == null) ? Json(false) : Json(!db.CRMTItems.Any(i => i.GbsNumber == gbsNumber));
    }
}

---

视图模型将整数值定义为可为null的int

int？

。可为空的int只有在包含值时才能与int进行比较

您的线路：

return Json(!db.CRMTItems.Any(i => i.GbsNumber == gbsNumber));

应测试空值：

return Json(!db.CRMTItems.Any(i => (i.GbsNumber ?? 0) == gbsNumber));

用GbsNumber不包含的值替换零

return Json(!db.CRMTItems.Any(i => i.GbsNumber == gbsNumber));

return Json(!db.CRMTItems.Any(i => (i.GbsNumber ?? 0) == gbsNumber));