这是我的模型:
Public Class subjectListModel
Public Property selectedActivity As String
Public Property activities As IEnumerable(Of SelectListItem)
End Class
以下是我的观点:
@Html.DropDownListFor(Function(x) x.selectedActivity, Model.activities, New With {.onchange = "this.form.submit();"})
这是我的控制器:
Function populateList()
'this is hardcoded at present, because I haven't been able to
'dynamically add to this IEnumerable. The implication is, I need a
'code change every time I add a new subject to my app ...
Dim model = New subjectListModel With {
.activities = {
New SelectListItem() With {.Value = activityList(0), .Text = activityList(0)},
New SelectListItem() With {.Value = activityList(1), .Text = activityList(1)},
New SelectListItem() With {.Value = activityList(2), .Text = activityList(2)},
New SelectListItem() With {.Value = activityList(3), .Text = activityList(3)},
New SelectListItem() With {.Value = activityList(4), .Text = activityList(4)},
New SelectListItem() With {.Value = activityList(5), .Text = activityList(5)},
New SelectListItem() With {.Value = activityList(6), .Text = activityList(6)},
New SelectListItem() With {.Value = activityList(7), .Text = activityList(7)},
New SelectListItem() With {.Value = activityList(8), .Text = activityList(8)},
New SelectListItem() With {.Value = activityList(9), .Text = activityList(9)}
}
}
Return View(model)
End Function
这工作正常,并显示一个下拉列表,其中包含我的前十个选项。我还有很多我想展示的。我已经考虑通过从我的字符串数组中动态添加项目然后尝试将其转换为 IEnumerable 来构建列表。我现在花了几个小时来查看似乎可以满足我想要的 C# 代码,但尽管进行了多次尝试,但我仍然无法在 VB 中使其正常工作。问题的很大一部分是我并不真正理解这些东西。任何帮助将不胜感激!
这是我尝试创建循环的一种方式:
Dim dropDown = New List(Of SelectListItem)
For j = 0 To 100
dropDown.Add(New SelectListItem With {.Text = activityList(j), .Value = activityList(j)})
Next j
然后我试图将其转换为IEnumerable。
这是我尝试创建循环的另一种方式:
Dim model = New subjectListModel
For j = 0 To 100
model.activities(New SelectListItem With {.Text = activityList(j), .Value = activityList(j)})
Next j
此错误为"参数过多">
您的第一个循环(分配给Dim dropDown = New List(Of SelectListItem)
)会创建IEnumerable(Of SelectListItem)
,因此您可以使用model.activities = dropDown
将其分配给subjectListModel
。
或者,您可以使用 LINQ 查询
model.activities = activityList.Select(Function(x) New SelectListItem()
With { .Text = x, .Value = x })
如果您只需要前 100 个项目,请添加.Take(100)
。