8: Working with Forms, Sessions, and Cookies in .NET framework

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8: Working with Forms, Sessions, and Cookies
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Attach input from a prior form submission to subsequent pages as hidden data:
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<html> <head></head> <body> < php // function to rewrite submitted values // as hidden form fields function importPrevPageData() { $hiddenDataStr = "<!-- input carried forward begins -->\n"; foreach ($_POST as $key => $value) { $hiddenDataStr = "<input type=\"hidden\" name=\"" htmlentities($key) "\" value=\"" htmlentities(stripslashes($value)) "\">\n"; } $hiddenDataStr = "<!-- input carried forward ends -->\n"; echo $hiddenDataStr; } // look for the page number // if not available, assume page 1 $pageID = isset($_POST['pageID']) $_POST['pageID'] : 1; // display pages by number switch ($pageID) { case 1: > <!-- page 1 --> <form method="post" action="< php echo $_SERVER['PHP_SELF']; >"> Name: <br /> <input type="text" name="name" size="30"> <br /> E-mail address:
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<br /> <input type="text" name="email"> <br /> Telephone: <br /> <input type="text" name="tel" size="10"> <br /> <input type="hidden" name="pageID" value=< php echo ($pageID+1); >> <input type="submit" name="submit" value="Go to Page 2"> </form> < php break; case 2: // perform validation of page 1 data // if errors, display error list // if no errors, display page 2 > <!-- page 2 --> <form method="post" action="< php echo $_SERVER['PHP_SELF']; >"> Card type: <br /> <select name="cctype"> <option value="V">Visa</option> <option value="M">MasterCard</option> <option value="A">AmEx</option> </select> <br /> Name on credit card: <br /> <input type="ccname" name="ccname" size="30"> <br /> Credit card expiration date (MM/YYYY): <br /> <input type="text" name="ccexp" size="7"> <br /> Email invoice: <br /> <input type="radio" name="email_invoice" value="Y">Yes <input type="radio" name="email_invoice" value="N">No <br />
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8: Working with Forms, Sessions, and Cookies
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<input type="hidden" name="pageID" value=< php echo ($pageID+1); >> < php // remove unnecessary form elements unset($_POST['submit']); unset($_POST['pageID']); // import previous form submission importPrevPageData(); > <input type="submit" name="submit" value="Place Order"> </form> < php break; case 3: // perform validation of page 2 data // if errors, display error list // if no errors, display page 3 // remove unnecessary form elements unset($_POST['submit']); unset($_POST['pageID']); // get all the submitted data as an array $data = $_POST; // process the data // for example, save to a database or file print_r($data); // print success message echo "Thank you for your order"; break; } > </body> </html>
Comments
A basic problem when dealing with forms spanning two or more pages involves transferring the data entered by the user from one page to the next To illustrate the
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problem, consider a three-page form that asks for the user s name (page 1) and e-mail address (page 2) before saving both to the database (page 3) To avoid errors, data submitted on the first page must be retained until the third page has completed processing The first solution to this problem involves rewriting the data submitted at each stage as a series of hidden form elements, and adding them to the next form page This carries forward form data from page to page, until it can all be processed on the final page You can see how this might work based on the previous listing, which calls the importPrevPageData() function each page of the form On each invocation, importPrevPageData() reads the $_POST array and rewrites its contents as a series of <input type="hidden" /> elements, which are then attached to the existing form and carried forward to the next page On the final page, the $_POST array will contain the data submitted over all the previous form pages This data can then be validated and processed in the usual manner The second solution to the problem involves using a session to store the data submitted at each stage, and processing it all at once on the final page This is somewhat less tedious than the previous alternative, mostly because of PHP s excellent built-in session handling capabilities, but it can fail if the client browser lacks (or has disabled) cookie support Here s the previous listing, rewritten to illustrate this approach:
< php // function to save submitted values // as session variables function importPrevPageData() { foreach ($_POST as $key => $value) { $_SESSION['form'][$key] = htmlentities(stripslashes($value)); } } // look for the page number // if not available, assume page 1 $pageID = isset($_POST['pageID']) $_POST['pageID'] : 1; // import previous session session_start(); > <html> <head></head> <body> < php // display pages by number switch ($pageID) {
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