我创建了一个运行良好的视图，直到我添加了一些 JQuery 来支持级联下拉菜单。我相信这样做，我打破了视图和模型之间的绑定。我收到错误“没有为此对象定义无参数构造函数”。提交表单时。显而易见的解决方案是添加一个无参数构造函数，但我假设 postmodel 将为空？下面的代码片段。
在此先感谢您的帮助。
看法：
<script type="text/javascript">
$(document).ready(function () {
$("#ddlCategories").change(function () {
var iCategoryId = $(this).val();
$.getJSON(
"@Url.Content("~/Remote/SubCategoriesByCateogry")",
{ id: iCategoryId },
function (data) {
var select = ResetAndReturnSubCategoryDDL();
$.each(data, function (index, itemData) {
select.append($('<option/>', { value: itemData.Value, text: itemData.Text }));
});
});
});
function ResetAndReturnSubCategoryDDL() {
var select = $('#ddlSubCategory');
select.empty();
select.append($('<option/>', { value: '', text: "--Select SubCategory--" }));
return select;
}
});
...
<div class="editor-field">
@Html.DropDownList("iCategoryID", Model.Categories,"--Select Category--", new Dictionary<string,object>{ {"class","dropdowns"},{"id","ddlCategories"}})
@Html.ValidationMessage("iCategoryID")
</div>
<div class="editor-label">
@Html.LabelFor(model => model.SubCategories, "SubCategory")
</div>
<div class="editor-field">
@Html.DropDownListFor(model => model.SubCategories, new SelectList(Enumerable.Empty<SelectListItem>(), "iSubCategoryID", "SubCategory",Model.SubCategories), "--Select SubCategory--", new { id = "ddlSubCategory" })
@Html.ValidationMessage("iSubCategoryID")
</div>
控制器：
[HttpPost]
public ActionResult Create(VendorCreateModel postModel)
{
VendorCreateEditPostValidator createValidator = new VendorCreateEditPostValidator(
postModel.iCategoryID,
postModel.iSubCategoryID,
postModel.AppliedPrograms,
m_unitOfWork.ProgramRepository,
new ModelStateValidationWrapper(ModelState));
if (ModelState.IsValid)
{
int categoryId = int.Parse(postModel.iCategoryID);
int subcategoryId = int.Parse(postModel.iSubCategoryID);
var programIds = postModel.AppliedPrograms.Select(ap => int.Parse(ap));
var programs = m_unitOfWork.ProgramRepository.GetPrograms(programIds);
Vendor vendor = postModel.Vendor;
vendor.Category = m_unitOfWork.CategoryRepository.GetCategory(categoryId);
vendor.SubCategory = m_unitOfWork.SubCategoryRepository.GetSubCategory(subcategoryId);
foreach (Program p in programs)
vendor.Programs.Add(p);
m_unitOfWork.VendorRepository.Add(vendor);
m_unitOfWork.SaveChanges();
return RedirectToAction("Index");
}
VendorCreateModel model = new VendorCreateModel(
postModel.Vendor,
postModel.iCategoryID,
postModel.iSubCategoryID,
postModel.AppliedPrograms,
User.Identity.Name,
m_unitOfWork.CategoryRepository,
m_unitOfWork.SubCategoryRepository,
m_unitOfWork.PermissionRepository);
return View(model);
}
遥控器：
[AcceptVerbs(HttpVerbs.Get)]
public JsonResult SubCategoriesByCateogry(int id)
{
System.Diagnostics.Debug.WriteLine(id);
var SubCategories = db.SubCategories
.Where(v => v.iCategoryID == id)
.OrderBy(v => v.sDesc)
.ToList();
var modelData = SubCategories.Select(v => new SelectListItem()
{
Text = v.sDesc,
Value = v.iSubCategoryID.ToString()
});
return Json(modelData, JsonRequestBehavior.AllowGet);
}
供应商创建模型：
public class VendorCreateModel
{
public VendorCreateModel()
{
}
public VendorCreateModel(
Vendor vendor,
string categoryId,
string subcategoryId,
IEnumerable<string> appliedPrograms,
string username,
ICategoryRepository categoryRepository,
ISubCategoryRepository subcategoryRepository,
IPermissionRepository permissionRepository)
{
UserHasProgramsValidator programValidator = new UserHasProgramsValidator(username, permissionRepository);
var availablePrograms = programValidator.AvailablePrograms;
HashSet<Category> applicableCategories = new HashSet<Category>();
foreach (var p in availablePrograms)
foreach (var c in categoryRepository.GetCategoriesByProgram(p.iProgramID))
applicableCategories.Add(c);
this.Vendor = vendor;
this.AppliedPrograms = appliedPrograms;
this.Categories = new SelectList(applicableCategories.OrderBy(x => x.sDesc).ToList(), "iCategoryID", "sDesc");
this.SubCategories = new SelectList(subcategoryRepository.GetAllSubCategories().OrderBy(x => x.sDesc).ToList(), "iSubCategoryID", "sDesc");
if (!string.IsNullOrEmpty(categoryId))
{
int temp;
if (!int.TryParse(categoryId, out temp))
throw new ApplicationException("Invalid Category Identifier.");
}
this.iCategoryID = categoryId;
this.iSubCategoryID = subcategoryId;
this.ProgramItems = availablePrograms
.Select(p => new SelectListItem()
{
Text = p.sDesc,
Value = p.iProgramID.ToString(),
Selected = (AppliedPrograms != null ? AppliedPrograms.Contains(p.iProgramID.ToString()) : false)
});
}
public Vendor Vendor { get; set; }
public SelectList Categories { get; set; }
public SelectList SubCategories { get; set; }
public string iCategoryID { get; set; }
public string iSubCategoryID { get; set; }
public IEnumerable<SelectListItem> ProgramItems { get; set; }
[AtLeastOneElementExists(ErrorMessage = "Please select at least one program.")]
public IEnumerable<string> AppliedPrograms { get; set; }
}