how to make a validation code for ASP.NET form with VB coding - asp.net

Question

im trying to build a form+attachment that needs to be send to email.
Im using a VB background code (attachementemail.aspx.vb)
and my front (b-16.aspx)
I want the page to check that the user entered a email, name, phonenumber and attachment.
what command do I put in the axp.vb
and what on the .aspx
tried just about anything.

Answer 1

The simplest way is to use validators eg RequiredFieldValidator for mandatory fields. You can also implement CustomValidators for custom logic.
See http://msdn.microsoft.com/en-us/e5a8xz39.aspx for the available validators

Answer 2

At it's basic level you could use RequiredFieldValidator and CustomValidation in your form. You can use some regex logic for email, I use this but there are many out there:
Regex(#"\w+([-+.]\w+)#\w+([-.]\w+).\w+([-.]\w+)*")
Personally I use client side javascript before it hits the server and then I re-validate the entries once it hits the server. If your using the postback events then you'll need update panels and a scriptmanager (not sure if you are aware of this already, so apologies if teaching you to suck eggs!).
Here is an example:
<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server"
ErrorMessage="RequiredFieldValidator" ControlToValidate="TextBox1"></asp:RequiredFieldValidator>
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="Button" />
<asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
</ContentTemplate>
</asp:UpdatePanel>
Code behind (sorry this is in c#)
protected void Button1_Click(object sender, EventArgs e)
{
if (RequiredFieldValidator1.IsValid)
{
Label1.Text = "Has content";
}
else
{
Label1.Text = "Not valid";
}
}
Note that the required field validator has it's own methods to display a "hey you haven't entered content here my friend" message, but i have added that to the label instead.