我有一个模型，其中包含有关帐户的一些详细信息（名称，ID等），然后它有一个名为Transaction的类型，其中包含有关当前所选帐户事务的信息。然后，事务可以具有许多事务线。所以我有一个List<TransactionsLine>属性。
我正在尝试使用模型设置下拉列表的值，该值位于List＆lt;＆gt;中属性。目前，可以而且必须只有列表中的一个项目。
@Html.DropDownListFor(x=>x.Transaction.TransactionLines[0].CategoryId, Model.TransactionReferences.Categories, new {@onchange="populateSubCategory()"})
但是，当我运行它时，列表默认为列表中的第一项。
在调试模式下，当我将鼠标悬停在x.Transaction.TransactionLines[0].CategoryId上时，它不会显示值。但是当鼠标悬停在集合Model.TransactionReferences.Categories上时，我看到它有一个有效的列表。它只是不会设置所选的值。
我这样做错了吗？
它适用于我使用的其他下拉菜单，但选择值是我模型的最高级别：
@Html.DropDownListFor(x => x.Transaction.ThirdPartyId, Model.TransactionReferences.ThirdParties, new { @class = "cmbThirdParty form-control", @onchange = "populateDefaults()" })
那个工作正常。
注意，手动执行，有效：
<select class="form-control" id="cmbCategory" onchange="populateSubCategory()">
<option value="0">Select a One</option>
@foreach (var cat in Model.TransactionReferences.Categories)
{
//var selected = cat.Value == Model.Transaction.TransactionLines[0].CategoryId.ToString() ? "selected" : "";
<option value="@cat.Value">@cat.Text</option>
}
</select>
但感觉不是最好的方法。
型号：
传递给视图的主要模型：
public class TransactionModel
{
public int BankAccountId { get; set; }
public string BankAccountName { get; set; }
public TransactionContainer Transaction { get; set; }
public TransactionReferenceModel TransactionReferences { get; set; }
public DateTime DefaultDate { get; set; }
}
TransactionReferenceModel保存用于填充下拉列表的所有“引用”数据：
public class TransactionReferenceModel
{
public List<SelectListItem> TransactionTypes { get; set; }
public List<SelectListItem> EntryTypes { get; set; }
public List<SelectListItem> SubCategories { get; set; }
public List<SelectListItem> Categories { get; set; }
public List<SelectListItem> ThirdParties { get; set; }
public List<SelectListItem> CostCentres { get; set; }
}
TransactionContainer模型包含有关所选交易的所有主要详细信息：
public class TransactionContainer
{
public int Id { get; set; }
public int AccountId { get; set; }
public int TransactionTypeId { get; set; }
public string TransactionType { get; set; }
public int EntryTypeId { get; set; }
public string EntryType { get; set; }
[DisplayFormat(ApplyFormatInEditMode = true, DataFormatString = "{0:dd/dd/yyyy}")]
public DateTime TransactionDate { get; set; }
public string ThirdParty { get; set; }
public int ThirdPartyId { get; set; }
public string Account { get; set; }
[DisplayFormat(ApplyFormatInEditMode = true, DataFormatString = "C2")]
public decimal Amount { get; set; }
public string Notes { get; set; }
public string CategoryDisplay { get; set; }
public string CostCentreDisplay { get; set; }
public decimal RunningBalance { get; set; }
public List<TransactionLine> TransactionLines { get; set; }
}
然后保存构成交易的交易行列表。事务行保存我尝试将下拉列表设置为的属性，即CategoryId：
public class TransactionLine
{
public int Id { get; set; }
public int TransactionId { get; set; }
public int? CostCentreId { get; set; }
public string CostCentre { get; set; }
public int SubCategoryId { get; set; }
public string SubCategory { get; set; }
public int CategoryId { get; set; }
public string Category { get; set; }
[DisplayFormat(ApplyFormatInEditMode = true, DataFormatString = "C2")]
public decimal Amount { get; set; }
public string Notes { get; set; }
}
以下是我填充模型并将其发送到视图的方式：
public ActionResult EditTransaction(int? transactionId, int? bankAccountId)
{
// Create the main view object
var model = new TransactionModel
{
Transaction = new TransactionContainer
{
TransactionLines = new List<TransactionLine>()
}
};
if (transactionId != null) // This is an Edit, as opposed to an Add
{
var item = new TransactionService(currentUserId).GetTransaction(transactionId.Value);
// Populate the Reference object used to populate drop downs.
model.TransactionReferences = PopulateReferenceDate(model.TransactionReferences, item.TransactionLines[0].SubCategoryId);
model.BankAccountId = item.AccountId;
model.BankAccountName = item.Account.FullName;
model.DefaultDate = Session["DefaultDate"] != null
? DateTime.Parse(Session["DefaultDate"].ToString())
: DateTime.UtcNow;
model.Transaction.AccountId = item.AccountId;
model.Transaction.Amount = item.Amount;
model.Transaction.TransactionLines.Add(new TransactionLine
{
Id = item.TransactionLines[0].Id,
CategoryId = item.TransactionLines[0].SubCategory.CategoryId,
CostCentreId = item.TransactionLines[0].CostCentreId,
Notes = item.TransactionLines[0].Notes,
Amount = item.TransactionLines[0].Amount,
SubCategoryId = item.TransactionLines[0].SubCategoryId,
TransactionId = model.Transaction.Id
});
model.Transaction.EntryTypeId = item.EntryTypeId;
model.Transaction.Id = transactionId.Value;
model.Transaction.Notes = item.Notes;
model.Transaction.ThirdPartyId = item.ThirdPartyId;
model.Transaction.TransactionDate = item.TransactionDate;
model.Transaction.TransactionTypeId = item.TransactionTypeId;
}
else
{
// Populate the bank account details
var bank = new BankAccountService(currentUserId).GetBankAccountById(bankAccountId.Value);
model.TransactionReferences = PopulateReferenceDate(model.TransactionReferences, null);
model.BankAccountId = bank.Id;
model.BankAccountName = bank.FullName;
model.Transaction.TransactionLines.Add(new TransactionLine
{
TransactionId = model.Transaction.Id // Link the transaction line to the transaction.
});
var transactionDate = Session["DefaultDate"] != null
? DateTime.Parse(Session["DefaultDate"].ToString())
: DateTime.UtcNow;
// Populate the object to hold the Transaction data, so that we can use it and return it in the view.
model.Transaction.TransactionDate = transactionDate;
}
return View(model);
}
答案 0 :(得分：1)
我认为您应该在视图中使用SelectList构造函数，以指示默认值，如下所示：
@Html.DropDownListFor(
x => x.Transaction.TransactionsLines[0].CategoryId,
new SelectList(Model.TransactionReferences.Categories, "Value", "Text", Model.Transaction.TransactionsLines[0].CategoryId)
)
您不限于使用 List＆lt;集合的SelectListItem＆gt; 。您也可以使用特定类的列表。
这是Controller Action Method代码：
public class HomeController : Controller
{
public ActionResult Index()
{
var m = new AccountModel();
m.Transaction = new Transaction();
m.Transaction.TransactionsLines = new List<TransactionsLine>();
m.Transaction.TransactionsLines.Add(new TransactionsLine() { CategoryId = 2 });
m.TransactionReferences = new TransactionReferences();
m.TransactionReferences.Categories = new List<SelectListItem>()
{ new SelectListItem() { Text = "Cat1", Value = "1" },
new SelectListItem() { Text = "Cat2", Value = "2" },
new SelectListItem() { Text = "Cat3", Value = "3" }
};
return View(m);
}
}