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How to use validator for drop-down list

Posted on 2010-11-11
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Last Modified: 2013-12-17

Hello group,

I'm using a drop-down list on a form (aspx page) where it has following items as value:

index 0 = "Select a value"
index 1 = "Value 1"
index 2 = "Value 2"
index 3 = "Value 3"

Now, my question is that can I use a validator in front-end (rather than writing a C# code) to make sure user is not saving the form with index 0 chosen?

Thanks!
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Comment
Question by:akohan
  • 3
  • 2
  • 2
  • +4
12 Comments
 
LVL 18

Expert Comment

by:Richard Lee
ID: 34112959
What type of validation do you want to perform?
0
 

Author Comment

by:akohan
ID: 34113049

that if index = 0 then show a message/warning to user to select any values from 1 to 3 but 0.

0
 
LVL 33

Accepted Solution

by:
Todd Gerbert earned 252 total points
ID: 34113275
Use a RangeValidator to ensure the user selects an option between 1 and 3 (or an appropriate range based on the number of items in your list).
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
		<asp:DropDownList ID="dropDown" runat="server">
			<asp:ListItem Text="Select an Option" Value="0" />
			<asp:ListItem Text="Value 1" Value="1" />
			<asp:ListItem Text="Value 2" Value="2" />
			<asp:ListItem Text="Value 3" Value="3" />
		</asp:DropDownList>
		<asp:RangeValidator ID="dropDownValidator" runat="server" ControlToValidate="dropDown"
			EnableClientScript="true" ErrorMessage="Select an Option" MaximumValue="3" MinimumValue="1" />
		<hr />
		<asp:Button ID="SaveButton" runat="server" Text="Save" />
    </div>
    </form>
</body>
</html>

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Author Comment

by:akohan
ID: 34113669


Thanks Tgerbert,

I used it but it is not working the way I want it. I think I'm missing something here pelase advise:

Basically my control in front-end is something like

            <asp:DropDownList ID="dropDown" runat="server">
            </asp:DropDownList>

and ListItem values are read from a table in runtime so as I was looking at Source Page I can see:


<select name="ctl00$ctl00$cph1$cph1$ctrlCustomerRegister" style="width:137px;">
                              <option value="A">Select One:</option>
                              <option value="E">Value 1</option>
                              <option value="R">Value 2</option>
                              <option value="S">Value 3</option>
 </select>

The problem is that when I choose a value from 1 to 3  I get a message as "You must select an option."

What am I missing here?

Thanks.


0
 
LVL 33

Expert Comment

by:Todd Gerbert
ID: 34113856
Well, as you can see your values are A, E, R and S, so yeah - if you setup the validator to require a value between 1 and 3 it's gonna complain. ;)
Use a CustomValidator to check that the selected option is not the first one in the list.

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
	<script language="javascript" type="text/javascript">
		function ValidateDropDown(source, arguments) {
			var dropdown = document.getElementById('<%= dropDown.ClientID %>');
			if (dropdown.selectedIndex == 0)
				arguments.IsValid = false;
			else
				arguments.IsValid = true;
		}
	</script>
</head>
<body>
    <form id="form1" runat="server">
    <div>
		<asp:DropDownList ID="dropDown" runat="server">
			<asp:ListItem Text="Select an Option" Value="0" />
			<asp:ListItem Text="Value 1" Value="1" />
			<asp:ListItem Text="Value 2" Value="2" />
			<asp:ListItem Text="Value 3" Value="3" />
		</asp:DropDownList>
		<asp:CustomValidator ID="dropDownValidator" runat="server" 
			ControlToValidate="dropDown" ErrorMessage="Select an Option" ClientValidationFunction="ValidateDropDown" />
		<hr />
		<asp:Button ID="SaveButton" runat="server" Text="Save" />
    </div>
    </form>
</body>
</html>

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0
 
LVL 41

Expert Comment

by:guru_sami
ID: 34114927
You use RequireFieldValidator and set InitialValue property to the value you want to validate against:

<asp:RequiredFieldValidator  ID="RequiredFieldValidator  1" runat="server" ErrorMessage="*Select A Value"  ControlToValidate="YourDDLID"  InitialValue="A"/>

See the  InitialValue="A" ...
0
 
LVL 41

Expert Comment

by:guru_sami
ID: 34114964
0
 
LVL 8

Expert Comment

by:cubaman_24
ID: 34119670
Hello:
As esay as this.
best regards
<asp:RequiredFieldValidator ID="rfvMyDropDown" runat="server" ControlToValidate="myDropDown"
                            Text="(*)"></asp:RequiredFieldValidator>

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0
 
LVL 1

Assisted Solution

by:NileshThakkar
NileshThakkar earned 248 total points
ID: 34122823
Hi

As you mentioned, below will be your dropdown list code:

 <asp:DropDownList ID="cboSignInType" runat="server">
                                            <asp:ListItem Text="--Select a value--" Value="0"></asp:ListItem>
                                            <asp:ListItem Text="Value 1" Value="1"></asp:ListItem>
                                            <asp:ListItem Text="Value 2" Value="2"></asp:ListItem>
                                            <asp:ListItem Text="Value 3" Value="3"></asp:ListItem>


And here  is validator which will fulfill your requirement. NO EXTRA code is required.

      <asp:RequiredFieldValidator ID="rqdSignInUserType" runat="server" ControlToValidate="cboSignInType" ValidationGroup="second" Display="Dynamic" ErrorMessage="*" InitialValue="0" EnableClientScript="true"></asp:RequiredFieldValidator>


Vote this if this answers your question
0
 

Author Comment

by:akohan
ID: 34243161

I will get back to you soon.
0
 
LVL 29

Expert Comment

by:Kumaraswamy R
ID: 34429101
This question has been classified as abandoned and is being closed as part of the Cleanup Program.  See my comment at the end of the question for more details.
0

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