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List:       php-general
Subject:    Re: [PHP] Form Retain Info on Back?
From:       Joona Kulmala <joona () fiveam ! org>
Date:       2003-07-31 20:48:47
[Download RAW message or body]

Hi

> I have a php form that I run a test to see if they have entered in
> all required fields before inserting into a MySQL db.  The PHP script
> simply reports what is missing and exits the rest of the page.
> However, when you click the back button, all the information that was
> entered, is gone.  Is there a simple way of retaining this
> information so the user doesn't has to retype all the information in?
> 
If you had a MySQL connection, I think that the easiest (also most safe
and stable) solution would be putting the POST-data and error-report
to session/temporary mysql-table. I've used this kind of solution on
several projects and it has work pretty well. In this you'll also need
to set some information to cookies so user must have cookies enabled on
his/her browser.


* MySQL-table

I've been using specifid session-table in my projects, which also
carries logged users sessionid and other session-data. But you can
also create specific temp-table for incomplete form-data. It could
be something like this

[sql]

CREATE TABLE temp_form_data (
	id int(10) UNSIGNED AUTO_INCREMENT NOT NULL PRIMARY KEY,
	stamp int(10) NOT NULL,
	data blob NOT NULL,
	error blob NOT NULL
);

[/sql]



* Form prosessing

Then in the form prosessing you could make some kind of error array
where to include error information. If any errors occur, save post
and error data to mysql and set cookie with mysqls
mysql_insert_id()

Example:
[code]

$error = array();

// validate fields how you like, I do regexps.
// check for email-address field.
if 
(!preg_match('/^([a-zA-Z0-9_\-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([a-zA-Z0-9\-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$/', \
 $_POST['mail'], $res))
{
     // make an new index to $error array, you can assign any value
     // you like for index.
     $error['mail'] = 1;
}

// check if any errors occured
if (count($error) > 0)
{
     // make a serialized dump of both $_POST and $error array

     $dump_data = addslashes(serialize($_POST));
     $dump_error = addslashes(serialize($error));

     // build a sql-query to update form and error data to mysql
     // table.

     $sql  = "INSERT INTO temp_form_data ";
     $sql .= "(date, data, error) ";
     $sql .= "VALUES (UNIX_TIMESTAMP(),'{$dump_data}','{$dump_error}')";

     // execute
     if (mysql_query($sql))
     {
         // set cookie
         setcookie('temp_form_data_id', mysql_insert_id());

         // get user back to form.
         // IMPORTANT: this must be before anything has been printed else
         // it won't work.
         header ("Location: form.php");
     }
     else
     {
         print "MySQL Error: " . mysql_error();
     }
}
else
{
     // FORM IS VALIDATED SUCCESFULLY
     // insert data
}

[/code]


* Form itself

In form you have to first check if "temp_form_data_id" cookie exists.
If does, you should load saved form data from db. After loading data
you should check before every field does error array have index matching
fields name. You should also assign values to fields from db.

Here's an example:
[code]

if (isset($_COOKIE['temp_form_data_id']) && 
!empty($_COOKIE['temp_form_data_id']))
{
     $id = $_COOKIE['temp_form_data_id'];

     // select
     $sql  = "SELECT * ";
     $sql .= "FROM temp_form_data ";
     $sql .= "WHERE id = {$id} ";

     // execute
     if ($q = mysql_query($sql))
     {
         // fetch row
         $result = mysql_fetch_row($q);

         // unserialize
         $error = unserialize(stripslashes($result['error']));
         $data = unserialize(stripslashes($result['data']));
     else
     {
         print "MySQL Error: " . mysql_error();
     }
}

if ($error) print '<h3>Form was filled incorrectly</h3>';

print '<form action="processer.php" method="post">';
if ($error['mail']) print '<b>Error: user valid email address</b><br>';
print 'Email address:<br>';
print sprintf('<input type="text" name="mail" value="%s">', $data['mail']);
print '<input type="submit" value="ok"></form>';

[/code]

This is how it should work. I hope you get the picture.

Cheers, Joona.

--
Joona Kulmala <joona@fiveam.org>
PHP Finland


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