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Preventing Repeat Form Submission Using PHP Sessions
We've all seen those messages on some websites warning not to click a button more than once or negative consequences, like paying a bill twice, may result. Sometimes we can cause these problems by hitting the back or refresh buttons. In this article I will explain a methodology whereby a site can ensure each form is submitted only once, thereby demonstrating that such warnings are unnecessary and, depending on the nature of the problems caused, worth repairing immediately. Let's begin by taking a look at the process we are studying: Form Submission. As pedantic as it may seem, it will be worthwhile to detail each of the steps in this process:
Since the item which changes does not depend on the form being submitted (e.g. it doesn't matter if it's a newsletter registration form, customer signup form, payment form, etc.), the item is not something which already exists and therefore must be created, so let's create a form variable called submissionId and assume it has the 3 properties mentioned above. So far, so good -- or so it appears! The third "property" is that "we can tell [it] changed", but "changed" is not a property of a variable, so we need to look at this more closely. In order to tell something changed, we must have a reference point, an answer to the question "changed from what?" This is where a session variable will come into play. If we define a session variable, say $_SESSION['nextValidSubmission'] and treat it as a reference point, we will have all of the tools necessary to protect our visitors. The idea will be to keep the session variable updated with the last submissionId sent out and change the submissionId each time it is sent out to the user. Then, if they try to resubmit the data, they will be submitting an old submissionId which doesn't match nextValidSubmission and we will know not to re-process this data. Let's look at this in terms of the processes:
Webmaster of Script Reference - The *NEW* PHP Reference & Tutorial Site For Non-Programmers
See here for more detailed information, an example using PHP, and an alternate method which doesn't require sessions.
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Optimize your time. How much time each day must you devote to paperwork, scheduling and accounting? You strive to meet the needs of your clients, but when chained to the obligations of business management, it's just as important to make sure the doors stay open as it is to satisfy customers. By integrating your daily tasks and taking advantage of the amazing Web-based software solutions out there, you can make more time for clients and spend less time behind your desk. Do you work from home? When your business is online, you can manage your business any place you have a connection to the Internet
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The first thing you will have to deal building your website has nothing to do with the web design itself, it's me related to content writing but it must be defined and will effect the rest of your actions. So first of all you need to decide what the topic of your future website is. Topic is very closely connected to another web design issue: keywords. The keywords you select will depend upon the topic you have chosen. When thinking about website topic ask yourself a few questions: What is the goal of the site you are making? What are you trying to achieve with your site. Specify a goal, preferably in one short sentence.
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Web Designer? You Dont Need No Stinkin Web Designer!
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