ValidationMessageFor仅适用于某些字段

Question

在我的表单中，有些字段似乎没有应用data-val="true"属性或任何其他data-val属性（即data-val-required，data-val-number，等等。）。前两个字段不起作用，但后面的字段正在工作。

@using (Html.BeginForm(null, null, FormMethod.Post, new { id = "PO_Form" }))
{
@Html.AntiForgeryToken()
@Html.ValidationSummary(true, "", new { @class = "text-danger" })

<div class="form-horizontal">
    <hr />
    <div class="form-group">
        @Html.LabelFor(model => model.PoNumber, "PO #", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.PoNumber, new { htmlAttributes = new { @class = "form-control" } })
            @Html.ValidationMessageFor(model => model.PoNumber, "", new { @class = "text-danger" })
        // doesn't work
        </div>
    </div>

    <div class="form-group">
        @Html.Label("Customer PO #", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.EditorFor(model => model.vendPoNumber, new { htmlAttributes = new { @class = "form-control" } })
            @Html.ValidationMessageFor(model => model.vendPoNumber, "", new { @class = "text-danger" })
        </div>
        // doesn't work
    </div>

    <div class="form-group">
        @Html.Label("Date", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.TextBoxFor(x => x.poDate, new { @Value = @DateTime.Now.ToShortDateString(), @class = "form-control datepicker" })
            @Html.ValidationMessageFor(model => model.poDate, "", new { @class = "text-danger" })
        </div>
    </div>

    <div class="form-group">
        @Html.Label("Company", "companyID", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            <div id="partialView">
                @{ Html.RenderPartial("_CompanyDropdown", Model);  }
            </div>
            @Html.ValidationMessageFor(model => model.companyID, "", new { @class = "text-danger" })
        </div>
    </div>

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

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

    <div class="form-group">
        <div class="col-md-offset-2 col-md-10">
            <input id="createPO" type="submit" value="Create" class="btn btn-success btn-sm" />
            <a href="@Url.Action("Index", "PurchaseOrders")"><span class="btn btn-sm btn-danger">Cancel</span></a>
        </div>
    </div>
</div>
}

生成实体框架的数据库第一SQL ...

    public int id { get; set; }
    public string PoNumber { get; set; }
    public string vendPoNumber { get; set; }
    public System.DateTime poDate { get; set; }
    public int companyID { get; set; }
    public decimal salesTax { get; set; }
    public decimal shipping { get; set; }

我如何使用服务器端验证？ 需要多个字段，但从未为EF更新中的这些字段生成[required]。