I have the following code in my Register.Aspx View page
<div class="FieldDropDown">
<%: Html.DropDownListFor(Function(m) m.Question, ViewData("Questions"), New With {.style = "margin-bottom: 24px; font-family: Tahoma; font-size: 12pt; color: #333333;"})%>
<%: Html.ValidationMessageFor(Function(m) m.Question)%>
</div>
The problem is that it keeps popping up an error and I cannot seem to tie down how EXACTLY to implement the code.
I do not have any custom or extra HTML Helpers defined by myself and assumed that it should just work without having to extend the default inbuilt MVC dropdownlistfor helper(?) methods.
The error that appears is…
Overload resolution failed because no accessible 'DropDownListFor' can be called without a narrowing conversion:
Extension method 'Public Function DropDownListFor(Of String)(expression As System.Linq.Expressions.Expression(Of System.Func(Of MvcApplication1.RegisterModel, String)), selectList As System.Collections.Generic.IEnumerable(Of System.Web.Mvc.SelectListItem), htmlAttributes As System.Collections.Generic.IDictionary(Of String, Object)) As System.Web.Mvc.MvcHtmlString' defined in 'System.Web.Mvc.Html.SelectExtensions': Argument matching parameter 'selectList' narrows from 'Object' to 'System.Collections.Generic.IEnumerable(Of System.Web.Mvc.SelectListItem)'.
Extension method 'Public Function DropDownListFor(Of String)(expression As System.Linq.Expressions.Expression(Of System.Func(Of MvcApplication1.RegisterModel, String)), selectList As System.Collections.Generic.IEnumerable(Of System.Web.Mvc.SelectListItem), htmlAttributes As System.Collections.Generic.IDictionary(Of String, Object)) As System.Web.Mvc.MvcHtmlString' defined in 'System.Web.Mvc.Html.SelectExtensions': Argument matching parameter 'htmlAttributes' narrows from '<anonymous type> (line 149)' to 'System.Collections.Generic.IDictionary(Of String, Object)'.
Extension method 'Public Function DropDownListFor(Of String)(expression As System.Linq.Expressions.Expression(Of System.Func(Of MvcApplication1.RegisterModel, String)), selectList As System.Collections.Generic.IEnumerable(Of System.Web.Mvc.SelectListItem), htmlAttributes As Object) As System.Web.Mvc.MvcHtmlString' defined in 'System.Web.Mvc.Html.SelectExtensions': Argument matching parameter 'selectList' narrows from 'Object' to 'System.Collections.Generic.IEnumerable(Of System.Web.Mvc.SelectListItem)'.
When I remove the HTMLATTRIBUTES to the following code below, then it works fine and no errors appear but then neither is the DropDownList styled and it just looks plain without the CSS formatting that I would like to have on it…
<div class="FieldDropDown">
<%: Html.DropDownListFor(Function(m) m.Question, ViewData("Questions"))%>
<%: Html.ValidationMessageFor(Function(m) m.Question)%>
</div>
What i’m trying to understand is…
Do I need to extend the htmlhelper for the dropdownlist?
Do I need to add something in my controller code?
My controller code is as follows…
<Required()> _
Public Property Question() As String
Get
Return _Question
End Get
Set(value As String)
_Question = value
End Set
End Property
Any pointers in the right direction or reference links would be helpful.
Thank You
Edit
This code below is inside my Reagister ACTION in the ACCOUNT controller.
'-> Okay
Item0 = NewQuestion("0", "Please select an option", True)
Item1 = NewQuestion("1", "What was your mothers maiden name?", False)
Item2 = NewQuestion("2", "Where were you born?", False)
Item3 = NewQuestion("3", "What was the name of your first love?", False)
Item4 = NewQuestion("4", "What was the name of your favourite pet?", False)
Item5 = NewQuestion("5", "What is the name of your favourite song?", False)
Item6 = NewQuestion("6", "What is the name of your idol/mentor?", False)
Item7 = NewQuestion("7", "What model of your first car?", False)
Item8 = NewQuestion("8", "What model was your first motorcycle?", False)
Item9 = NewQuestion("9", "Who is your favourite sports-person?", False)
Item10 = NewQuestion("10", "What was your last ACTIVATION KEY?", False)
SQuestions = Nothing
SQuestions = New SelectList({Item0, Item1, Item2, Item3, Item4, Item5, Item6, Item7, Item8, Item9, Item10}, Item0)
Session("Website_Guest") = ThisGuest
ViewData("VisitorName") = ThisGuest.Username
'ViewData("Questions") = New SelectList(SQuestions.Items) <- TRIED IT LIKE THIS TOO
'ViewData("Questions") = New SelectList(SQuestions) <- TRIED IT LIKE THIS TOO
ViewData("Questions") = sQuestions
ViewData("PasswordLength") = MembershipService.MinPasswordLength
Return View()
And this is the NEWQUESTION Function which outputs a selectlistitem
Private Function NewQuestion(NewValue As String, NewData As String, NewSelected As Boolean) As SelectListItem
Dim Item As SelectListItem = Nothing
Item = Nothing
If Trim(NewValue) <> "" Then
If Trim(NewData) <> "" Then
Item = New SelectListItem()
Item.Value = NewValue
Item.Text = NewData
Item.Selected = NewSelected
End If
End If
Return Item
Item = Nothing
End Function
So in essence, I am passing a selectlist in the first instance so thats why i did not cast into another selectlist – although like i said in my comment it DOES fix the styling but leaves me with another issue re: the photo below shows what i get..
Closure
Thank you everyone who helped me figure this out, I’ve marked one of them as the answer as that persons answer helped me pinpoint the issue, it doesnt neccessarily means the other answer was wrong, its probably my lack of understanding more than anything.
to resolve the issue I looked again at the way i was passing the viewdata and although i DID pass a SELECTLIST, i reverted to passing a SELECTLIST.ITEMS collection and then in the VIEW i re-scoped the passed data to a selectlist, and now the data is visible instead of selectlist objects AND it has the HTMLATTRIBUTES appended in the HTML.DROPDOWNLISTFOR method.
Thanks everyone.
I don’t know why you are only getting an error when you include the attributes object, but I think the problem is with ViewData(“Questions”) returning an
Object, not anIEnumerable(Of SelectListItem), so try:Something similar at http://forums.asp.net/t/1466151.aspx/1