Converting mvc razor C-Sharp to VB.NET razor

Question

User2130491911 posted

So for about 3 weeks not I have been having problems making a drop down list in the mvc.

what is beyond frustrating is that I have this working in one of the c# applications that I created.

Now I need to use that data structure in a VB.Net application but sadly all usable examples are in the c-shape flavor.

I made a post here a few days ago that no one could give me clear guidance on so now looking at some of my other application built in c-sharp I notice that I have done the thing there. 

For some reason the c-shape converts can't do the razor conversion so maybe some guru here can help

I will post what I have working in the c-sharp followed by what I need to work in the Vb.nets

The Razor in the C-sharp

            @Html.DropDownListFor(model => model.Company_ID, (SelectList)ViewBag.CompanyList, new { @class = "form-control", @id = "COMPANY_DLL" })



                    //Populate Drop Downs List
                    //ViewBag.CompanyList = new SelectList(CUPS_DDL.GetCAMSCompanys(), "Value", "Text", model.Company_ID);
                    ViewBag.CompanyList = new SelectList(Enumerable.Empty<SelectListItem>());

The Razor stuff
@Html.DropDownListFor(model => model.JWS_CONTEST_ID, new SelectList(ViewBag.ContestList, "CT_CONTEST_ID", "CT_CONTEST_DESCRIPTION"))




The C-sharp stuff
            var Contest_List = db.CT_CONTEST_MASTER_TBL.ToList();

            if (Contest_List != null)
            {
                ViewBag.ContestList = Contest_List;
            }

So the above works and in this case the razor stuff allows me to tell the computer to use CT_CONTEST_ID", "CT_CONTEST_DESCRIPTION as the Value and text I guess

The other C-sharp razor code does not have the Value and Text Listed out , THis one

 @Html.DropDownListFor(model => model.Company_ID, (SelectList)ViewBag.CompanyList, new { @class = "form-control", @id = "COMPANY_DLL" })

If I am honest I am not 100% sure how these work as I have yet to find any clear guidance on this. I just use my working examples, But now I need to convert this functionality to VB.Nets and there is no clear guidance. I was hoping someone could help me translate this from C-sharp to VB.net

My VB.Net Examples:

 The VB.NEts Razor stuff (works But only shows the table names vs Value and Text Info

               @Html.DropDownListFor(Function(model) model.Code_Reference, CType(ViewBag.RefCodesList, SelectList))

The VB.net COde

Make the List 
        'GET CLE-LIST
        Function GET_CODE_REF_List() As List(Of CODE_REF_LOV_TBL)


            'Fetch Records From Table using EF
            Dim REF_CODES_LIST As List(Of CODE_REF_LOV_TBL) = (From CODE In db.CODE_REF_LOV_TBL Select CODE).ToList()


            'Insert The Defau't Item To the LOV
            REF_CODES_LIST.Insert(0, New CODE_REF_LOV_TBL With {.CODE_REF_REC_ID = "0", .CODE_DESCRIPTION = "PLEASE SELECT"})


            Return (REF_CODES_LIST)

        End Function





Connect the list to viewbag
        ' GET: CO/Create
        Function Create() As ActionResult

            'Get LOV
            'Dim customerList As List(Of SelectListItem) = GET_CODE_REF_List()
            ViewBag.RefCodesList = New SelectList(GET_CODE_REF_List())


            Return View()
        End Function

This may make it clearer 

So this may be a better question to ask show that I have this stuff working in a different language. But now I am trying to get it work in another that I have been a way from for a while (Never did the mvc in VB.net) So I am having trouble getting the concepts to work since for some reason the example in VB.Net are even worst then the C-sharp examples.

Answer 1

User2130491911 posted

Ok after making some changes based of of this very unhelpful write up

https://visualstudiomagazine.com/articles/2011/09/01/pcovb_razor-vb/listing4.aspx

I did the following changes 

I changed this

                @Html.DropDownListFor(Function(model) model.Code_Reference, CType(ViewBag.RefCodesList, List(Of SelectListItem)))

To This but now I get just the word Selectlistitem repeated lol (So frustrating this thing lol

                @Html.DropDownListFor(Function(model) model.Code_Reference, ViewBag.RefCodesList)

But I also changed my function that makes my list and now  it causes this to error our

                @Html.DropDownListFor(Function(model) model.Code_Reference, CType(ViewBag.RefCodesList, List(Of SelectListItem)))

This has a error of when Running:

System.InvalidCastException: 'Unable to cast object of type 'System.Web.Mvc.SelectList' to type 'System.Collections.Generic.List`1[System.Web.Mvc.SelectListItem]'.'

But I am guessing because I am changing the the way the list is created??

I was creating this way based on the write up

        'GET CLE-LIST
        Function GET_CODE_REF_List() As List(Of SelectListItem)


            'Fetch Records From Table using EF

            Dim REF_CODES_LIST = (From c In db.CODE_REF_LOV_TBL Select New SelectListItem With {.Text = c.CODE_DESCRIPTION, .Value = c.CODE_REF_REC_ID}).ToList()

            'Dim REF_CODES_LIST As List(Of CODE_REF_LOV_TBL) = (From CODE In db.CODE_REF_LOV_TBL Select CODE).ToList()


            'Insert The Defau't Item To the LOV
            'REF_CODES_LIST.Insert(0, New CODE_REF_LOV_TBL With {.CODE_REF_REC_ID = "0", .CODE_DESCRIPTION = "PLEASE SELECT"})


            Return REF_CODES_LIST

        End Function

At this point I am trying anything I can find and I just keep getting errors 

This Yields 

    @Html.DropDownListFor(Function(model) model.Code_Reference, CType(ViewBag.RefCodesList, List(Of SelectListItem)), "CODE_REF_REC_ID", "CODE_DES")

THis error 

System.InvalidCastException: 'Unable to cast object of type 'System.Web.Mvc.SelectList' to type 'System.Collections.Generic.List`1[System.Web.Mvc.SelectListItem]'.'

This is promising :

                @Html.DropDownListFor(Function(model) model.Code_Reference, ViewBag.RefCodesList)

But all it list is this for every entry in the list:

system.web.mvc.selectlistitem

It this last change tells me I am close but computer is not telling me what to do. All the examples claim this should work but it does not. so I am guessing I have the VB converted but I am back a square one lol

Really not sure what it happening.  Any insight would be great.

Answer 2

User475983607 posted

Your Html.DropDownListFor overload is incorrect.  It's just...

@Html.DropDownListFor(Function(model) model.CourseID, CType(ViewBag.RefCodesList, List(Of SelectListItem)))

This assumes you populated ViewBag.RefCodesList correctly which I cannot verify.

Function Index() As ActionResult

    ViewBag.RefCodesList = GET_CODE_REF_List()
    Return View()

End Function

Answer 3

User2130491911 posted

mgebhard

Your Html.DropDownListFor overload is incorrect.  It's just...

@Html.DropDownListFor(Function(model) model.CourseID, CType(ViewBag.RefCodesList, List(Of SelectListItem)))

This assumes you populated ViewBag.RefCodesList correctly which I cannot verify.

Function Index() As ActionResult

    ViewBag.RefCodesList = GET_CODE_REF_List()
    Return View()

End Function

THis is my error sadly

System.InvalidCastException: 'Unable to cast object of type 'System.Collections.Generic.List`1[BFR_LOCAL_DB.CODE_REF_LOV_TBL]' to type 'System.Collections.Generic.List`1[System.Web.Mvc.SelectListItem]'.'

It just may be time for me to give up on this. Clearly something is wrong with the mvc and it can no long support dropdownlist for vb.net

Yeah as I stated on the other post. I will just put the values in a onscreen table and the user will have to enter them in by typing them

This is way too much of a headache lol Dropdownlist in VB.net is way too hard of a concept fro me on this day. Maybe if I have to revisit this in the future I will try it again Thanks All for trying.