我在ASP MVC 4中使用DropDownListFor设置DropDownList的默认选择值时遇到问题。
当我想要预选的属性在列表中时,默认情况下从未按预期选择。
这是我的代码简化为重要的东西:
型号:
public class Renter
{
...
public virtual List<RentLine> RentLines { get; set; }
...
public Renter()
{
...
RentLines = new List<RentLine>();
...
}
}
public class RentLine
{
...
public Guid RenterId { get; set; }
public virtual Renter Renter { get; set; }
public Guid GarageId { get; set; }
public virtual Garage Garage { get; set; }
...
public RentLine()
{
//
// Testcase for default value in dropdownlist
//
GarageId = new Guid("e926dcac-05ac-4fc1-92a2-014345e6e11c");
}
}
控制器:
public ActionResult Hinzufuegen()
{
var model = new AddRenterViewModel();
return View(model);
}
视图模型:
public class AddRenterViewModel
{
public Renter Renter { get; set; }
public List<SelectListItem> RentableGarageItems { get; set; }
...
public AddRenterViewModel()
{
Renter = new Renter();
Renter.RentLines.Add(new RentLine());
RentableGarageItems = new List<SelectListItem>();
foreach (var garage in Singleton.Instance.Entities.GetRentableGarages().OrderBy(g => g.No))
{
RentableGarageItems.Add(new SelectListItem{Text = garage.No.ToString(), Value = garage.Id.ToString()});
}
}
}
查看:
@model Grossgaragenverwaltung.ViewModels.AddRenterViewModel
...
Garage Nr. @Html.DropDownListFor(m => m.Renter.RentLines[0].GarageId, Model.RentableGarageItems) @* No selected value *@
@Html.TextBoxFor(m => m.Renter.RentLines[0].GarageId) @* Shows the id 'e926dcac-05ac-4fc1-92a2-014345e6e11c' as set in the constructor *@
...
结果如下,没有选定值:
Garage Nr.
<select id="Renter_RentLines_0__GarageId" name="Renter.RentLines[0].GarageId" data-val-required="Das Feld "GarageId" ist erforderlich." data-val="true">
<option value="225a761d-7d12-4e02-9d72-d54fb6934f05">1</option>
<option value="d28fb4fb-d65b-4674-90d6-a4ab9636be80">2</option>
<option value="e06b520b-e876-4870-b321-dc65f77967a7">3</option>
<option value="56832d98-aa5a-4e1a-af44-2d7e00f2bb3a">4</option>
<option value="551f1fa9-13a5-40ce-b795-50063e605027">5</option>
<option value="bace4b40-92ab-4757-9716-2a2878c2c9e8">6</option>
<option value="f9baf45b-96bf-463e-a234-a1522bfc9b9b">7</option>
<option value="91d1d866-6346-4ab0-b2aa-35b56eeaf2b0">8</option>
<option value="62eb3727-eab2-4180-90cd-7dc59119f44e">9</option>
<option value="59768097-c772-4421-b907-a24397a106f5">10</option>
<option value="270acf6b-e4e3-41c3-86dd-4381a313848a">11</option>
<option value="923269cd-1ead-4346-90ce-6344acda5b1b">12</option>
<option value="981ee61e-408b-4b08-a7d3-26c909f04a9d">13</option>
<option value="f1c5043c-fe41-4a8e-8c58-e88363885de4">14</option>
<option value="e926dcac-05ac-4fc1-92a2-014345e6e11c">15</option>
<option value="5577dc00-7cfa-4bcd-99ad-3f356e4325ae">16</option>
</select>
<input id="Renter_RentLines_0__GarageId" type="text" value="e926dcac-05ac-4fc1-92a2-014345e6e11c" name="Renter.RentLines[0].GarageId">
我怎样才能完成这项工作?
更新: 这是一个工作示例,其中一切都像预期的那样工作,只有在您看到上述情况时才会出现问题:
public class Renter
{
...
public Salutation Salutation { get; set; }
...
public Renter()
{
...
Salutation = Salutation.Male;
...
}
}
public ActionResult Hinzufuegen()
{
var model = new AddRenterViewModel();
return View(model);
}
public class AddRenterViewModel
{
public Renter Renter { get; set; }
public List<SelectListItem> SalutationItems { get; set; }
...
public AddRenterViewModel()
{
Renter = new Renter();
Renter.RentLines.Add(new RentLine());
SalutationItems = new List<SelectListItem>();
foreach (Salutation salutation in Enum.GetValues(typeof(Salutation)))
{
SalutationItems.Add(new SelectListItem { Text = NameEnum.GetName(salutation), Value = salutation.ToString() });
}
}
}
@Html.DropDownListFor(m => m.Renter.Salutation, Model.SalutationItems)
<select id="Renter_Salutation" name="Renter.Salutation" data-val-required="Das Feld "Salutation" ist erforderlich." data-val="true">
<option value="Company">Firma</option>
<option value="Male" selected="selected">Männlich</option>
<option value="Female">Weiblich</option>
</select>
答案 0 :(得分:8)
经过一些研究dropdownlistfor does not select correct value in a loop后,我找到了解决方案。
这有效:
@Html.DropDownListFor(m => m.Renter.RentLines[0].GarageId,
new SelectList(Model.RentableGarageItems, "Value", "Text", Model.Renter.RentLines[0].GarageId))
答案 1 :(得分:2)
您在SelectedListItem创建中缺少 Selected 属性。即选择=(garage.Id == 2)
var entities = new List<Guarage>()
{
new Guarage() {No = 1, Id = 1},
new Guarage() {No = 2, Id = 2},
new Guarage() {No = 3, Id = 3}
};
foreach (var garage in entities)
{
var s = new SelectListItem
{
Text = garage.No.ToString(),
Value = garage.Id.ToString(),
Selected = (garage.Id == 2)
};
RentableGarageItems.Add(s);
}
默认情况下,这会在下拉列表中选择2。
答案 2 :(得分:0)
内联Stephen Muecke对MVC5 Razor html.dropdownlistfor set selected when value is in array
的回答不幸的是,
@Html.DropDownListFor()
在循环中渲染控件时的行为与其他助手的行为略有不同。这已经被报道为CodePlex上的一个问题(不确定它是否是一个错误或只是一个限制)有两个选项可以解决这个问题,以确保根据模型属性选择正确的选项
选项1 - 使用
EditorTemplate
为集合中的类型创建自定义
EditorTemplate
。在/Views/Shared/EditorTemplates/AggregationLevelConfiguration.cshtml
中创建部分(请注意,名称必须与类型名称匹配@model yourAssembly.AggregationLevelConfiguration @Html.DropDownListFor(m => m.HelperCodeType, (SelectList)ViewData["CodeTypeItems"]) .... // other properties of AggregationLevelConfiguration
然后在主视图中,将
SelectList
传递给EditorTemplate
additionalViewData
@using (Html.BeginForm()) { ... @Html.EditorFor(m => m.Configurations , new { CodeTypeItems = Model.CodeTypeItems }) ...
选项2 - 在每次迭代中生成新的
SelectList
并设置selectedValue
在此选项中,您的媒体资源
CodeTypeItems
应该是IEnumerable<GenericIdNameType>
,而不是SelectList
(或只是将codeTypes
设为公共财产)。然后在主视图中@Html.DropDownListFor(m => m.Configurations[0].HelperCodeType, new SelectList(Model.CodeTypeItems, "Id", "Name", Model.Configurations[0].HelperCodeType)
旁注:无需使用
new { id = "Configurations[0].HelperCodeType"
-DropDownListFor()
方法已生成id
属性
注意:另外,请仔细检查您是否还有其他非列表相关的绑定问题,如以下问题所述: