我无法在下拉列表中设置默认值 [英] I cannot set default value on dropdownlistfor
问题描述
我有一个构造函数，该构造函数传入一个对象的IEnumerable，然后将其从类型为 SelectList 的公共变量中公开.在cshtml文件中，它已映射到DropDownListFor，并且下拉列表填充良好，但是当我尝试将"None selected"附加到下拉列表时，它不会显示在屏幕上，例如
I have a constructor that passes in an IEnumerable of an object and then expose it from a public variable of type SelectList. In the cshtml file It has been mapped to a DropDownListFor and the dropdown populates fine, However when I try to attach "None selected" to the dropdown it doesn't display in the screen e.g.
视图模型的构造函数:
IEnumerable<Partner> beneficiaryNames
在构造函数中设置值:
BeneficiaryNames = new SelectList(beneficiaryNames, "Id", "Name");
viewmodel中的声明:
declaration in viewmodel:
public SelectList BeneficiaryNames { get; set; }
然后在我看来:
@Html.DropDownListFor(m => m.SearchRequest.BeneficiaryId, Model.BeneficiaryNames, "None selected")
推荐答案
在视图模型的构造函数中，我不得不将一个新对象强制放入列表中.因此我不得不用 List< Partner>替换 BeneficiaryNames = new SelectList(beneficiaryNames，"Id"，"Name"); newList = new List< Partner>(){新伙伴{ID = 0，名称=未选择"}};newList.AddRange(受益人名称);BeneficiaryNames = new SelectList(newList，"Id"，"Name");
in the constructor of the view model I had to force a new object into the list. so I had to replace BeneficiaryNames = new SelectList(beneficiaryNames, "Id", "Name"); with List<Partner> newList = new List<Partner>() { new Partner { Id = 0, Name = "None Selected" } };
newList.AddRange(beneficiaryNames);
BeneficiaryNames = new SelectList(newList, "Id", "Name");
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