How to construct DropDownList in VB.NET

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Hi Everyone,

I am in need of some help with constructing a drop down list within vb.net server side.

I have found i can start with something like

VB

Dim dl As New DropDownList

but iam stuck as of how to continue, i have search online for help but it all looks confusing.

I need to populate the DropDownList with data from a stored procedure

if you need anymore code or info please ask

Thank you

I have tried filling in the DDL in with the following code but nothing is populated

VB

If Request.QueryString("userid") <> "" Then

            Dim ddlResult As New DataSet
            ddlResult = GetUserName.ddlData(Request.QueryString("userid").ToString)

            sysDDL.DataSource = ddlResult
            sysDDL.DataValueField = "description"
            sysDDL.DataTextField = "description"
            sysDDL.DataBind()
            sysDDL.Items.Insert(0, New ListItem(String.Empty, String.Empty))
            sysDDL.SelectedIndex = 0

        End If

New Code...

DIV containing DDL

XML

<div id="dUserSystems" runat="server" >
        <u>Systems user has access to</u><br />
            <div id="dUserData"></div>
        <br />

    <div id="ddlSysData" runat="server" >
         <u>Add new system to users account</u><br />
         <asp:DropDownList ID="sysDDL" runat="server"/>
    </div>
        <br />
        <input type="button" id="butAdd" value="Add" runat="server"/>&nbsp;
        <input type="button" onclick="butClose()" value="Close" />
</div>

My function that calls data from a stealth page to create a table for 'dUserData' and i think i may need to add something in here for the DDL to work?

JavaScript

function viewSystems(myUserid) {


       var link = 'fetchData.aspx?userid=' + myUserid;

       $.get(link, function (data) {

           $("#dUserData").empty().append(data);
           $("#ContentPlaceHolder1_dUserSystems").css("left", "200px");
           $("#ContentPlaceHolder1_dUserSystems").css("display", "block");
       });


     }

   function butClose() {
       $("#ContentPlaceHolder1_dUserSystems").css("display", "none");
   }

Posted 21-Jan-15 0:52am

Member 11355710

Updated 21-Jan-15 3:57am

v6

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Sinisa Hajnal · Answer 1 · 2015-01-21T01:11:00

Solution 1

1. Get the data in DataSet or DataTable (or list, collection etc)
2. set DataTextField and DataValueField - first is column name that is shown to the user, second one is the value you get for dl.SelectedValue
3. Set dl.DataSource to your data (whatever that is)

Read detailed description here[^] - it wasn't hard to find and it is clear, step-by-step with code examples and download.

Put some more effort into it next time.

Code:
You don't need New DropDownList, if you do it this way you have to add it to the page somewhere. Instead, put

ASP.NET

<asp:DropDownList id="dl" runat="server" />

where you need it in your html.

Server side:

VB

If Request.QueryString("userid").Trim <> String.Empty Then

            Dim ddlResult As New DataSet
            ddlResult = GetUserName.ddlData(Request.QueryString("userid").ToString)

        dim dr as DataRow = ddlResult.Tables(0).NewRow
        dr("description") = string.Empty
        ddlResult.Tables(0).Rows.InsertAt(dr, 0)
        ddlResult.AcceptChanges()

            sysDDL.DataValueField = "description"
            sysDDL.DataTextField = "description"
            sysDDL.DataSource = ddlResult.Tables(0)
            sysDDL.DataBind()
        End If

Posted 21-Jan-15 1:11am

Sinisa Hajnal

Updated 21-Jan-15 3:28am

v2

Comments

Member 11355710 21-Jan-15 7:27am

Thank you Sinisa but i am new to vb.net and i have not created a DDL this way before so i am confused of what i need. You list makes sense but i am unsure of how to turn this into code

Sinisa Hajnal 21-Jan-15 7:31am

That is why I supplied you with the link where it is described in detail. Being new does not excuse you from searching and learning. I realize it is hard without someone senior next to you, but persistence pays. And once you "get it" you'll never have to ask again for all types of similar controls. So...keep reading, check the link, download and understand the code...and you'll be the one answering the questions in ... decade or so :p

Member 11355710 21-Jan-15 7:42am

Thank you for your comments but i really needed some help with a starting point of code as after reading the link provided before asking this question it doesnt help me with my issue. I am using a Stored Procedure and a QueryString before i construct the DDL. I completely agree with researching and learning but after reading 20/30 pages none of them have a simple DDL construct im looking for so i thought i would try asking the question.

Sinisa Hajnal 21-Jan-15 9:23am

But the point is: you already have your data in form of GetUserName.ddlData(Request.QueryString("userid").ToString)

So, assign data column names to properties mentioned above and assign datasource. That really is all. The controls are actually very simple. You can get into tweaks later, but the initial simple binding is exactly that, simple.

I apologize for the comment about the effort put into this, but there are lots of exact code examples - you have to only copy and paste them, change column names and you're done.

The above IS starting point. What you're asking is for finished code. I'll edit the solution, but this really shouldn't be neccessary.

Sinisa Hajnal 21-Jan-15 9:28am

There. Check the solution.

Member 11355710 21-Jan-15 9:43am

Thank you i have tried the code but the DDL is still not being populated. Should this work or is there something else i need to add?

Sinisa Hajnal 21-Jan-15 9:48am

If you removed New DropDownList and added it into HTML then it should work. Can you make sure it gets called? Put a breakpoint on If Request.QueryString("userid") and see if it dataset gets filled.

Member 11355710 21-Jan-15 9:57am

I have removed new ddl and added to my html side. I have added more code to my question hope this helps with the reason no data in ddl.

Sinisa Hajnal 21-Jan-15 10:10am

OK. Remove your "stealth" page. Add the code for data retrieval in your page. You can later play with moving it around. I believe there was a suggestion of doing refactoring earlier...

So...instead of having hidden page to do your data retrieval, create data management class that you can reference and call its methods. It doesn't have to be a page.

Member 11355710 21-Jan-15 10:14am

Unfortunately i am unable to remove the stealth page as this is what i have been asked to do. This was the reason for me asking about the 'As New DropDownList' so i could construct the DDL on the stealth page_load event which would be the simplest options for me i just cant find the information i need. p.s thank you for your constant help today

Sinisa Hajnal 22-Jan-15 2:09am

This is an information that you should've mentioned much earlier. All the above is waste of time this way.

Let's start over: what kind of information do you get from fetchdata page? I see you're filling div element with it, but what is its format? Right now, it looks like it would be more efficient to retrieve the data from that div and construct your selection list from jQuery rather then do another round trip to server. Why is this page required?

Sinisa Hajnal 22-Jan-15 2:11am

I'm mostly out of my workplace today adn tomorrow, I'll be able to answer maybe once more today and again tomorrow, so please think about your answer. I would also recommend you open new question with the relevant information and post the link here.

In that question, post the link to this question too.

Member 11355710 22-Jan-15 3:35am

I have created another question which all the information in i can think is needed here is the link. Again thank you for your help.
http://www.codeproject.com/Questions/868328/How-to-fill-vb-net-dropdownlist-with-stealth-call

Sinisa Hajnal · Answer 2 · 2015-01-21T04:11:00

OK. Remove your "stealth" page. Add the code for data retrieval in your page. You can later play with moving it around. I believe there was a suggestion of doing refactoring earlier...

So...instead of having hidden page to do your data retrieval, create data management class that you can reference and call its methods. It doesn't have to be a page.

In AppCode folder add:

VB

public class UserManager
public function GetUser(id as string) as datatable
' whatever you need to do to return the table
end function
End Class

in your page:

VB

dim um as new UserManager()
dim dt as datatable = um.GetUser(QueryString("id"))
...the rest of the code to assign dt as datasource to your dropdown.