Thread: dynamically created dropdowns insert to sql

Hey everyone its peebman2000, currently still building the questionnaire vb.net app for my client.

I've never worked with creating dynamic controls before, but a functionality the client wants, I feel creating dropdownlist dynamically would work.

Below is code I found on line and it works, but I need to insert the data or values from each dynamically created dropdownlist into sql.

I have no clue on how to do that, I know I'll have to creat another for loop, but i'm lost on how to grab or capture the selected values from the dropdownlist that are created.

Does anyone know how to grab the values from dynamically created dropdownlists? So I may be able to store the data in SQL.

Thanks for the help.


aspx.vb page:

Code:

    Protected Sub SubmitBtn_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles butOK.Click
        'Dim dt As SqlDataSource
        'dt = Sqldatasource1
        'dt.DataBind()

        ''code to dynamically create dropdownlist
        'Dim I As Integer
        'Dim J As Integer
        'For I = 1 To txtNumber.Text
        '    Dim MyDDL = New DropDownList
        '    MyDDL.ID = "ddlDynamic" & I
        '    For J = 1 To 3
        '        Dim MyLI As New ListItem
        '        'MyLI.Text = "Control Number: " & I & "-" & J
        '        'MyLI.Value = I & J

        '        MyDDL.Items.Add(MyLI)
        '        ''MyDDL.Items.Add(dt)
        '        'MyDDL.DataSourceID = Sqldatasource1.ID
        '        'MyDDL.DataBind()
        '    Next
        '    form1.Controls.Add(MyDDL)
        '    Dim MyLiteral = New LiteralControl
        '    MyLiteral.Text = "<BR><BR>"
        '    form1.Controls.Add(MyLiteral)
        'Next



        '''''code to dynamically create dropdownlist with data bounded to dropdownlist
        Dim I As Integer
        'Dim J As Integer
        For I = 1 To txtNumber.Text
            Dim MyDDL As New DropDownList
            MyDDL.ID = "ddlDynamic" & I
            form1.Controls.Add(MyDDL)
            MyDDL.DataSourceID = Sqldatasource1.ID

            MyDDL.DataValueField = "agency_name"
            MyDDL.DataBind()
            Dim MyLiteral = New LiteralControl
            MyLiteral.Text = "<BR><BR>"
            form1.Controls.Add(MyLiteral)
        Next


    End Sub

aspx page:

Code:

 <form id="form1" runat="server">
    <div>
    <B>Enter the number of DropDownList controls you want:</B><BR><BR>
<asp:TextBox 
    id="txtNumber" 
    runat=server 
/>
<BR><BR>
<asp:button 
    id="butOK"
    text="OK"
    
    runat="server"
/>
<BR><BR>

    </div>
    
<asp:sqldatasource ID="Sqldatasource1" runat="server" ConnectionString="<%$ ConnectionStrings:peebman %>" SelectCommand="SELECT agency_name FROM dbo.agency"></asp:sqldatasource>
    </form>

Hey thanks, I'll be using a stored procedure to store in sql, but I need to capture the value in the dropdownlists.

I tried to do a response.write to see if i'm getting the values from the dropdownlists using ddlDynamic1.selectedindex.value

Code:

Response.Write(ddlDynamic.selectedindex.value)

and I get a not declared error for ddlDynamic.

If I can just capture the values in the dropdownlist, I can insert it into Sql.

Any ideas on how I can capture the selected values, because the ddlDynamic.selectedinex.value didn't work or I may be doing something wrong in how I should use your suggestion. Thanks

Originally Posted by jmurrayhead

Couldn't you just use: ddlDynamic1.SelectedIndex.Value to get the value and then append it to your query?

Thanks, I tried that and it still says:

Name 'ddlDynamic1' is not delcared

I'm using:

Code:

Response.Write(ddlDynamic1.selectedindex.value)

any idea why is not recognizing the ddlDynamic1?

Originally Posted by jmurrayhead

From looking at this line:

Code:

MyDDL.ID = "ddlDynamic" & I

ddlDynamic will have an integer after it...so:

Code:

Response.Write(ddlDynamic1.selectedindex.value)

Hey Jmurrayhead, that workd, but I need to separate each selectedvalue from each dropdown.

i tried using the same for loop like in the code below, but that didn't work.

How can I separate each selected value for each dropdownlist?

aspx.vb code:

Code:

Protected Sub SubmitBtn_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles butOK.Click
        'Dim dt As SqlDataSource
        'dt = Sqldatasource1
        'dt.DataBind()

        ''code to dynamically create dropdownlist
        'Dim I As Integer
        'Dim J As Integer
        'For I = 1 To txtNumber.Text
        '    Dim MyDDL = New DropDownList
        '    MyDDL.ID = "ddlDynamic" & I
        '    For J = 1 To 3
        '        Dim MyLI As New ListItem
        '        'MyLI.Text = "Control Number: " & I & "-" & J
        '        'MyLI.Value = I & J

        '        MyDDL.Items.Add(MyLI)
        '        ''MyDDL.Items.Add(dt)
        '        'MyDDL.DataSourceID = Sqldatasource1.ID
        '        'MyDDL.DataBind()
        '    Next
        '    form1.Controls.Add(MyDDL)
        '    Dim MyLiteral = New LiteralControl
        '    MyLiteral.Text = "<BR><BR>"
        '    form1.Controls.Add(MyLiteral)
        'Next



        '''''code to dynamically create dropdownlist with data bounded to dropdownlist
        Dim I As Integer
        'Dim J As Integer
        For I = 1 To txtNumber.Text
            Dim MyDDL As New DropDownList
            MyDDL.ID = "ddlDynamic" & I
            form1.Controls.Add(MyDDL)
            MyDDL.DataSourceID = Sqldatasource1.ID
            'MyDDL.AutoPostBack = True

            MyDDL.DataValueField = "agency_name"
            MyDDL.DataBind()
            Dim MyLiteral = New LiteralControl
            MyLiteral.Text = "<BR><BR>"
            form1.Controls.Add(MyLiteral)


        Next
        'Dim i As Integer
        'For I = 1 To txtNumber.Text
        '    Dim dropdownlist1 As DropDownList = CType(Me.FindControl("ddldynamic1"), DropDownList)
        '    'dropdownlist1.AutoPostBack = True

        '    Response.Write(dropdownlist1.SelectedValue)


        '    'Response.Write(form1.Controls(ddlDynamic1.selectedindex.value))
        'Next
    End Sub

    Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim i As Integer

        For i = 1 To txtNumber.Text
            Dim dropdownlist1 As DropDownList = CType(Me.FindControl("ddldynamic1"), DropDownList)

            Response.Write(dropdownlist1.SelectedValue)


            'Response.Write(form1.Controls(ddlDynamic1.selectedindex.value))
        Next
    End Sub

Originally Posted by jmurrayhead

You'll have to create an instance and use FindControl like so:

Code:

Dim DropDownList1 As DropDownList = CType(Me.FindControl("ddlDynamic1"), DropDownList)
Response.Write(DropDownList1.SelectedValue)

Kind of, i'm trying to use the button1 click event to display the selectedvalues in each dropdownlist and I need them to be separated.

aspx.vb code:

Code:

 Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim i As Integer

        For i = 1 To txtNumber.Text
            Dim dropdownlist1 As DropDownList = CType(Me.FindControl("ddlDynamic" & i), DropDownList)

            Response.Write(dropdownlist1.SelectedValue)


            'Response.Write(form1.Controls(ddlDynamic1.selectedindex.value))
        Next
    End Sub

but when i hit submit I get an error now:

Server Error in '/questionaire' Application.
--------------------------------------------------------------------------------

Object reference not set to an instance of an object.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error:


Line 87: Dim dropdownlist1 As DropDownList = CType(Me.FindControl("ddlDynamic" & i), DropDownList)
Line 88:
Line 89: Response.Write(dropdownlist1.SelectedValue)
Line 90:
Line 91:


Source File: C:\Documents and Settings\Peebman2000\Desktop\wizard\questionaire\d ropdownlistdynmc.aspx.vb Line: 89

Stack Trace:


[NullReferenceException: Object reference not set to an instance of an object.]
dropdownlistdynmc.Button1_Click(Object sender, EventArgs e) in C:\Documents and Settings\Peebman2000\Desktop\wizard\questionaire\d ropdownlistdynmc.aspx.vb:89
System.Web.UI.WebControls.Button.OnClick(EventArgs e) +105
System.Web.UI.WebControls.Button.RaisePostBackEven t(String eventArgument) +107
System.Web.UI.WebControls.Button.System.Web.UI.IPo stBackEventHandler.RaisePostBackEvent(String eventArgument) +7
System.Web.UI.Page.RaisePostBackEvent(IPostBackEve ntHandler sourceControl, String eventArgument) +11
System.Web.UI.Page.RaisePostBackEvent(NameValueCol lection postData) +33
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1746




--------------------------------------------------------------------------------
Version Information: Microsoft .NET Framework Version:2.0.50727.1433; ASP.NET Version:2.0.50727.1433

Any ideas on what i'm doing wrong?

Originally Posted by jmurrayhead

Code:

        For i = 1 To txtNumber.Text
            Dim dropdownlist1 As DropDownList = CType(Me.FindControl("ddldynamic" & i), DropDownList)
 
            Response.Write(dropdownlist1.SelectedValue)
 
 
            'Response.Write(form1.Controls(ddlDynamic1.selectedindex.value))
        Next

Do you mean like how the above will output?