How to put data from a database into javascript array from asp.net/vb.net

Question

I am trying to make a simple program to put data from a database into a javascript array and then display one result in a textbox. Here is what I have so far

        Dim cmd As New IfxCommand("select first 20 fname from table", conn)
    Dim reader As IfxDataReader = cmd.ExecuteReader(CommandBehavior.CloseConnection)
    Dim i As Integer = 0
    While reader.Read()
        ClientScript.RegisterArrayDeclaration("Names", "'" & reader("fname") & "'")
        i += 1


    End While
    Dim cs As StringBuilder = New StringBuilder()
    cs.Append("<script type=""text/javascript\""> function DoIt() {")
    cs.Append("var TheTextBox = document.getElementById(""TextBox1"");")
    cs.Append("TheTextBox.value = Names[0];")
    cs.Append("script>")
    TextBox1.Text = cs.ToString

Here is the asp

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>Untitled Page</title>
</head>
<body>
<form id="form1" runat="server">
<div>

</div>
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<p>
    <asp:Button ID="Button1" runat="server" Text="Button" onclick = "DoIt"/>
</p>
</form>
</body>
</html>

I am not sure what else I am supposed to do with this.

Is there any reason why you don't use ASP.NET to display the values in a TextBox? — Tim Schmelter
– Tim Schmelter, Commented Jun 20, 2012 at 13:25
eventually I want to iterate through an array but if I did it through asp it would refresh the page everytime — user867621
– user867621, Commented Jun 20, 2012 at 13:27

Tim Schmelter · Accepted Answer · 2012-06-20 14:21:22Z

1

So you want to display the first name of your selected 20 in the TextBox initially and maybe lazy-load the other from client side via javascript?

Try this:

Using cmd = New IfxCommand("select first 20 fname from table", conn)
    Dim tbl = New DataTable
    Using reader = cmd.ExecuteReader()
        tbl.Load(reader)
        If tbl.Rows.Count <> 0 Then
            Dim allNames = From row In tbl
                           Select row.Field(Of String)("fname")
            TextBox1.Text = allNames.First
            ' embed names with quotes and separate the strings by comma '
            Dim embeddedNames = From name In allNames Select String.Format("'{0}'", name)
            ClientScript.RegisterArrayDeclaration("Names", String.Join(",", embeddedNames))
        End If
    End Using
End Using

Now you only need to implement the javascript function that switches the names if necessary. You can use String split then:

var allNames = documentGetElementById("Names").value.split(",");

edited Jun 20, 2012 at 14:21

answered Jun 20, 2012 at 13:39

Tim Schmelter

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6 Comments

user867621 Over a year ago

i'm getting an error on the clientscript line saying that it can't be converted to 1 dimensional array of string

Tim Schmelter Over a year ago

@user867621: So all works on serverside and you also have already implemented the clientside functionality to iterate the names? Can i see it? Have you debugged javascript (or at least took a look at the source) to see what happens?

user867621 Over a year ago

i meant it won't let me compile because this line ClientScript.RegisterArrayDeclaration("Names", String.Join(",", allNames)) It has the squigglies under allNames saying what the first comment said

Tim Schmelter Over a year ago

@user867621: Oh yes, i haven't embedded the names with single quotes('John','James','Jim') which is necessary for javascript string-arrays. I've edited my answer accordingly.

user867621 Over a year ago

it still won't compile.... Error 1 Value of type 'System.Data.EnumerableRowCollection(Of String)' cannot be converted to '1-dimensional array of String'.

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