列表框的MVC数据验证不起作用

Question

即使我的listboxfor为空，我的表单也会遇到一些问题。这是使用以下的viewmodel：

 public class CopyExcelReportSearchViewModel: IViewModel
{
    [Required]
    public DateRange DateRange { get; set; }
    [Required]
    public Guid CustomerId { get; set; }
    [Required]
    public List<Guid> ProjectIds { get; set; }
    [Required]
    public List<Guid> LocationsIds { get; set; }
    public List<Customer> AvailableCustomers { get; set; }
    public List<Project> AvailableProjects { get; set; }
    public List<Location> AvailableLocations { get; set; }

    public CopyExcelReportSearchViewModel()
    {
        ProjectIds = new List<Guid>();
        LocationsIds = new List<Guid>();
        AvailableCustomers = new List<Customer>();
        AvailableProjects = new List<Project>();
        AvailableLocations = new List<Location>();
    }
}

这是html

@model    Path.CopyExcelReportSearchViewModel
@{
var customerDropdown = Model.AvailableCustomers.Select(x => new SelectListItem
{
    Text = x.Name,
    Value = x.Id.ToString(),
    Selected = Model.CustomerId == x.Id
});
var locationDropdown = Model.AvailableLocations.Select(x => new SelectListItem
{
    Text = x.Name,
    Value = x.Id.ToString(),
    Selected = Model.LocationsIds.Any(y => y == x.Id)
});
var projectDropdown = Model.AvailableProjects.Select(x => new SelectListItem
{
    Text = x.Name,
    Value = x.Id.ToString(),
    Selected = Model.ProjectIds.Any(y => y == x.Id)
});
}

<script>
    var optionTemplate = [
       '<option value="[VALUE]">[TEXT]</option>'
    ].join();

    $(function () {
        $('#CustomerId').change(function () {
            var value = $(this).val();
            $.ajax({
                url: '@Url.Action("GetProjectsByCustomerId")?customerId=' + value,
                datatype: 'json',
                type: 'GET',
                cache: false,
                success: function (data) {
                    var projectSelect = $('#ProjectIds');
                    var options = '';
                    for (var i = 0; i < data.length; i++) {
                        options += optionTemplate.replace('[VALUE]', data[i].id).replace('[TEXT]', data[i].name);
                    }
                    projectSelect.empty().append(options).removeAttr('disabled').trigger('chosen:updated');
                }
            });
        });
        $('#CustomerId').trigger('change');
    });
</script>
@using (Html.BeginForm("GenerateCopyReportExcel", "Report",     FormMethod.Post))
{
//todo - Fix projectids validation

<div id="DlgStockReportSearch" class="modal fade" data-backdrop="static" tabindex="-1">
    <div class="modal-dialog">
        <div class="modal-content">
            <div class="modal-header">
                <button type="button" class="close" data-dismiss="modal" aria-hidden="true">×</button>
                <h3>@Language.KPIReport</h3>
            </div>
            <div class="modal-body clearfix">
                <div class="col-xs-12">
                    <div class="form-group">
                        <label for="CustomerId">@Language.Customer</label>
                        @Html.DropDownListFor(x => x.CustomerId, customerDropdown, new { @class = "form-control chosen", placeholder = Language.Customer })
                        @Html.ValidationMessageFor(x => x.CustomerId)
                    </div>
                    <div class="form-group required">
                        <label for="DateRange">@Language.Date</label>
                        @Html.EditorFor(x => x.DateRange)
                    </div>
                    <div class="form-group">
                        <label for="ProjectIds">@Language.Projects</label>
                        <div class="input-group button">
                            @Html.ListBoxFor(x => x.ProjectIds, projectDropdown, new { @class = "form-control chosen", multiple = ""})
                            @Html.ValidationMessageFor(m => m.ProjectIds)
                            <span class="input-group-addon">
                                <button type="button" class="btn btn-default chosen-select-all">Select all</button>
                            </span>
                        </div>
                    </div>
                    <div class="form-group">
                        <label for="LocationsIds">@Language.Location</label>
                        <div class="input-group button">
                            @Html.ListBoxFor(x => x.LocationsIds, locationDropdown, new { @class = "form-control chosen", multiple = "" })
                            <span class="input-group-addon">
                                <button type="button" class="btn btn-default chosen-select-all">Select all</button>
                            </span>
                        </div>
                    </div>
                </div>
            </div>
            <div class="modal-footer">
                <button type="button" class="btn btn-default" data-dismiss="modal" aria-hidden="true">@Language.Close</button>
                <button type="submit" class="btn btn-primary">
                    @Language.GenerateReport
                </button>
            </div>
        </div>
    </div>
</div>
}

出于某种原因，即使我将项目和地点的listboxfor留空，我也可以提交表格。