Wrox Programmer Forums
|
BOOK: Beginning ASP.NET 4.5 : in C# and VB
This is the forum to discuss the Wrox book Beginning ASP.NET 4.5: in C# and VB by Imar Spaanjaars; ISBN: 978-1-118-31180-6
Welcome to the p2p.wrox.com Forums.

You are currently viewing the BOOK: Beginning ASP.NET 4.5 : in C# and VB section of the Wrox Programmer to Programmer discussions. This is a community of software programmers and website developers including Wrox book authors and readers. New member registration was closed in 2019. New posts were shut off and the site was archived into this static format as of October 1, 2020. If you require technical support for a Wrox book please contact http://hub.wiley.com
 
Old April 3rd, 2013, 10:56 AM
Friend of Wrox
 
Join Date: May 2011
Posts: 411
Thanks: 13
Thanked 7 Times in 7 Posts
Default State code validation

Say for instance that you have a webform that allows customers to post back information to the server for processing. On this webform you have a state field as a text box. Is there a front end validation tool that comes with Visual Studio out of the box that would say only allow the user to put in state codes for Arizona, Texas, Wyoming, California, Nevada, Maryland, and Florida and exclude or throw a validation era for all the other states besides the ones I just listed? In other words if they entered state codes into the texbox that were not part of the above mention state code list, it would throw a validation message/error. Is there an out of the box Validation tool in Visual Studio 2012 that can handle this scenario? I know that you can do it on the front end with JavaScript as follows:
Code:
var $ = function (id) {
    return document.getElementById(id);
}
var stateCodeLookup = function (stateCode) {
	var states = ["CA", "WA", "OR", "NV", "NM", "AZ", "WY", "MT", "TX","FL"];
	stateCode = stateCode.toUpperCase();
	for (var i = 0; i < states.length; i++) {
		if (states[i] == stateCode) {
			return true;
		} 
	}
	return false;
}
var joinList = function () {
	var emailAddress1 = $("email_address1").value;
	var emailAddress2 = $("email_address2").value;
	var isValid = true;
	
	// validate the first email address
	if (emailAddress1 == "") { 
		$("email_address1_error").firstChild.nodeValue = "This field is required.";
		isValid = false;
	} else {
		$("email_address1_error").firstChild.nodeValue = "";
	} 
	
	// validate the second email address
	if (emailAddress2 == "") { 
		$("email_address2_error").firstChild.nodeValue = "This field is required.";
		isValid = false; 
	} else if (emailAddress1 !== emailAddress2) { 
		$("email_address2_error").firstChild.nodeValue = "This entry must equal first entry.";
		isValid = false;
	} else {
		$("email_address2_error").firstChild.nodeValue = "";
	}
	
	// validate the first name entry  
	if ($("first_name").value == "") {
		$("first_name_error").firstChild.nodeValue = "This field is required.";
		isValid = false;
	} 
	else {
		$("first_name_error").firstChild.nodeValue = "";
	}
	
	// validate the state code entry
	var stateCode = $("state_code").value;
	if (!stateCodeLookup(stateCode)) {
		$("state_code_error").firstChild.nodeValue = "State code is invalid.";
		isValid = false;
	} 
	else {
		$("state_code_error").firstChild.nodeValue = "";
	}
	
	// submit the form if all entries are valid
	if (isValid) {
		$("email_form").submit(); 
	}
}
window.onload = function () {
    $("join_list").onclick = joinList;
    $("email_address1").focus();
}
I am just wondering if there is a more simple and elegant way to do this using Visual Studio validation tools that run on the back end?
 
Old April 3rd, 2013, 11:02 AM
Imar's Avatar
Wrox Author
 
Join Date: Jun 2003
Posts: 17,089
Thanks: 80
Thanked 1,576 Times in 1,552 Posts
Default

Nope, there's nothing out of the box in VS or .NET for this. You need to write your own or search the web for similar implementations already written by others.

Two comments: make sure you also validate at the server (using a CustomValidator), or consider using a DropDownList as it nicely limits the list of options as well.

This is getting a bit too off-topic for this forum category for my book. Would you mind posting questions like these that are not directly related to my book in a general category here: http://p2p.wrox.com/book-beginning-a...-4-5-c-vb-710/ This way, other people can contribute to and learn from the discussion as well.

Cheers,

Imar
__________________
Imar Spaanjaars
http://Imar.Spaanjaars.Com
Follow me on Twitter

Author of Beginning ASP.NET 4.5 : in C# and VB, Beginning ASP.NET Web Pages with WebMatrix
and Beginning ASP.NET 4 : in C# and VB.
Did this post help you? Click the button below this post to show your appreciation!
 
Old April 3rd, 2013, 04:22 PM
Friend of Wrox
 
Join Date: May 2011
Posts: 411
Thanks: 13
Thanked 7 Times in 7 Posts
Default Okay while I have you here let me ask a follow up question.

So if you do a front end validation on your webform, if the user puts in incorrect information into a webform object and pushes the submit button, does that prevent the web form from being posted back the server or does it just post back the server anyway and then throw an validation error message to user after the post back?
 
Old April 3rd, 2013, 04:27 PM
Imar's Avatar
Wrox Author
 
Join Date: Jun 2003
Posts: 17,089
Thanks: 80
Thanked 1,576 Times in 1,552 Posts
Default

It depends. If you implement a client side validation function then yes, it will prevent the form from being submitted. If you only provide server side validation, then it requires a postback in order to be triggered.

Imar
__________________
Imar Spaanjaars
http://Imar.Spaanjaars.Com
Follow me on Twitter

Author of Beginning ASP.NET 4.5 : in C# and VB, Beginning ASP.NET Web Pages with WebMatrix
and Beginning ASP.NET 4 : in C# and VB.
Did this post help you? Click the button below this post to show your appreciation!
 
Old April 3rd, 2013, 05:01 PM
Friend of Wrox
 
Join Date: May 2011
Posts: 411
Thanks: 13
Thanked 7 Times in 7 Posts
Default Okay then....

theoretically you can stop the user from posting any kind of malicious stuff on to the server by nipping it in the bud by validating on the front end? Is that not correct?
 
Old April 3rd, 2013, 05:43 PM
Imar's Avatar
Wrox Author
 
Join Date: Jun 2003
Posts: 17,089
Thanks: 80
Thanked 1,576 Times in 1,552 Posts
Default

>> Is that not correct?

No, it's not correct. As explained in the book, it's easy to bypass client side validation by disabling JavaScript or by crafting your own direct HTTP requests. Server side validation is the only real form of validation; client side is just a courtesy to the user.

Imar
__________________
Imar Spaanjaars
http://Imar.Spaanjaars.Com
Follow me on Twitter

Author of Beginning ASP.NET 4.5 : in C# and VB, Beginning ASP.NET Web Pages with WebMatrix
and Beginning ASP.NET 4 : in C# and VB.
Did this post help you? Click the button below this post to show your appreciation!





Similar Threads
Thread Thread Starter Forum Replies Last Post
Code validation Isabella C# 3 January 4th, 2012 06:01 PM
selective validation Country/State dsmportal ASP.NET 2.0 Professional 3 August 9th, 2006 04:01 PM
selective validation Country/State dsmportal ASP.NET 1.0 and 1.1 Professional 0 August 3rd, 2006 12:35 PM
how to use view state in code behind files in C# ajeshss C# 4 June 20th, 2006 06:00 AM
Session State|View State|Do I have other options? rockon ASP.NET 1.x and 2.0 Application Design 2 October 5th, 2005 07:10 PM





Powered by vBulletin®
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Copyright (c) 2020 John Wiley & Sons, Inc.