在 POST 编辑中保存表单不起作用

Question

我有一个控制器方法，我试图保存在视图中编辑的表单。

[HttpPost]
public ActionResult ModifyContract(ModContract mod)
{
    // submit modified contract
    if (ModelState.IsValid)
    {
        OutlookMediaEntities1 db = new OutlookMediaEntities1();

        db.ObjectStateManager.ChangeObjectState(mod, EntityState.Modified);

        // save changes
        db.SaveChanges();

        return RedirectToAction("ContractDetails", "Contract", new { id = (int) ViewData["contractid"] });
    }
    else
    {
        ModelState.AddModelError("", "Missing necessary information");
        return View();
    }
}

我在 db.ObjectStateManager... 行收到 InvalidOperationException。我看到一些东西说这可能是因为我没有分配主键并注意到我的 ModAds 类（如下）不包含主键。添加了它，但我得到了同样的错误。我尝试按照我之前问题中回答者的建议执行 db.Attach(mod) ，但出现编译器错误。 Attach 将“IEntityWithKey”作为参数。所以显然我的实体没有密钥，所以我认为我声明模型内容的方式一定有问题。

    public class ModContract
    {
        public int contract_id; // primary key?
        public string contract_name { get; set; }
        public List<ModAds> ads;

        public string print_product_id { get; set; }
        public string print_ad_option_id { get; set; }
    }

    public class ModAds
    {
        public int contr_ad_id; // primary key?
        public string name;
        public string product_name;
        public string adv_product;
        public List<string> editions;
        public double freq_disc;
        public double other_dis_dol;
        public double? other_dis_per;
        public string non_cash_note;
        public double non_cash_cons;
    }

有没有办法指定主键是什么？我的模型有点奇怪，因为如您所见，我在 ModContract 中有一个 ModAd 列表。不确定这是否是个问题。我还尝试在所有字段中添加 getter 和 setter 以查看是否是问题所在，但我遇到了同样的错误。

我也尝试使用db.Entry(model).State = EntityState.Modified; 进行保存，但没有成功，因为我使用的是 EF 4.0。

非常感谢任何帮助！

编辑

我想我知道出了什么问题，模型是由一堆不同的数据库表组成的，即没有表 ModContract。我很确定我必须以某种方式将模型内容分散到适当的表和列中..

编辑 2

OutlookMediaEntities1 的粘贴箱：http://pastebin.com/YyrhjGDA

编辑 3

这是 GET ModifyContract 方法，它显示了我如何查询数据库以创建模型。

    public ActionResult ModifyContract(int id)
    {
        ViewData["contractid"] = id; // save id

        // get data from db
        OutlookMediaEntities1 db = new OutlookMediaEntities1();
        var cont = from printContractAd in db.print_contract_ads
                   from printContracts in db.print_contracts
                   where printContracts.contract_id == id
                   select new { printContracts.contract_id, printContracts.note }; // name

        // select the ads for this contract
        var ads = from printContractAd in db.print_contract_ads
                  from printAdOption in db.print_ad_option
                  from printContract in db.print_contracts
                  from printProduct in db.print_products
                  from contractAdCount in db.Contract_ad_edition_count
                    where printContractAd.print_ad_option_id == printAdOption.print_ad_option_id &&
                          printContract.contract_id == printContractAd.contract_id &&
                          printProduct.print_product_id == printAdOption.print_product_id &&
                          contractAdCount.contract_ad_id == printContractAd.contract_ad_id &&
                          printContract.contract_id == id
                  select new
                  {
                      printContractAd,
                      printAdOption,
                      printProduct,
                      printContract.IsSigned,
                      contractAdCount.CountFreq
                  };

        ModContract con = new ModContract();
        foreach (var c in cont) // only one
        {
            con.contract_id = c.contract_id;
            con.contract_name = c.note;

            break; // only one
        }

        List<ModAds> cads = new List<ModAds>();
        foreach (var ad in ads)
        {
            ModAds mad = new ModAds();
            mad.contr_ad_id = ad.printContractAd.contract_ad_id;
            mad.product_name = ad.printProduct.product_name;
            mad.adv_product = ad.printAdOption.name;
            mad.name = ad.printContractAd.note;
            mad.freq_disc = ad.printContractAd.frequency_discount;
            mad.other_dis_dol = ad.printContractAd.other_discount;
            mad.other_dis_per = ad.printContractAd.other_discount_percent;
            mad.non_cash_note = ad.printContractAd.non_cash_note;
            mad.non_cash_cons = ad.printContractAd.non_cash_discount; // consideration?

            // get editions
            var eds = from contractEditions in db.print_contract_editions
                      where contractEditions.contract_ad_id == ad.printContractAd.contract_ad_id
                      select new
                          {
                              contractEditions
                          };
            mad.editions = new List<string>();
            foreach (var ed in eds)
            {
                mad.editions.Add("Volume " + ed.contractEditions.vol.ToString() + " Issue " + ed.contractEditions.issue.ToString());
            }

            cads.Add(mad);
        }

        con.ads = cads;

        // bind dropdownlist ad options
        var printproductList = from printProduct in db.print_products
                               select printProduct;
        List<SelectListItem> products_list = new List<SelectListItem>();
        List<print_products> products = printproductList.ToList();
        foreach (print_products product in products)
        {
            SelectListItem temp_item = new SelectListItem();
            temp_item.Text = product.product_name;
            temp_item.Value = product.print_product_id.ToString();
            products_list.Add(temp_item);
        }
        ViewData["products_list"] = new SelectList((IEnumerable<SelectListItem>)products_list.ToList(), "Value", "Text");

        // return view with form to modify
        return View(con);
    }

编辑 4

如果有帮助，这也是视图（我无法在此处获得格式）：http://pastebin.com/SZvzJ9FB

Answer 1

对于更新实体，实体必须附加到Data Context。这样做可以使用Single 方法从数据上下文中获取实体就足够了。 尝试像这样更改您的代码：

[HttpPost]
public ActionResult ModifyContract(ModContract mod)
{
    // submit modified contract
    if (ModelState.IsValid)
    {
        OutlookMediaEntities1 db = new OutlookMediaEntities1();

        var updatedMod = db.ModContract.Single(m=>m.contract_id == mod.contract_id);
        TryUpdateModel<ModContract>(updatedMod);
        // save changes
        db.SaveChanges();

        return RedirectToAction("ContractDetails", "Contract", new { id = (int) ViewData["contractid"] });
    }
    else
    {
        ModelState.AddModelError("", "Missing necessary information");
        return View();
    }
}

Answer 2

你可以告诉 EF contract_id 是关键：

public class ModContract
{
    [Key]
    public int contract_id;
}

并确保属性映射到的数据库列是 PK。尽管它是否是 IDENTITY 可能很重要，这取决于您如何使用它。

Answer 3

您可以在 ModAds 类中的主键上方添加 [Key] 属性。