Building A Quick-And-Dirty PHP/MySQL Publishing System - Splitting Up
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Next, "add.php". If you think about it, you'll realize that this script actually has two components to it: a form, which displays fields for the administrator to enter information, and a form processor, which validates the input and inserts it into the database.
Now, I could write this as two separate scripts; however, it's a habit of mine to put both components into the same script and wrap a conditional test around them to decide which one gets used when. So, the broad outline of my "add.php" script would look like this:
<?
// form not yet submitted
// display initial form
if (!$submit)
{
// code to display form goes here
}
// form submitted
// process it
else
{
// code to process form data goes here
}
?>
Based on the presence or absence of the $submit variable, the
script can take a decision as to whether to display the initial form, or initiate the form processor.
Now, when an administrator first accesses the page through a browser, the $submit variable will not exist, and so control will shift to the first section of the script, which displays an HTML form. Let's look at that first:
<?
// add.php - add a new press release
?>
<!-- page header - snip -->
<?
// form not yet submitted
// display initial form
if (!$submit)
{
?>
<table cellspacing="5" cellpadding="5">
<form action="<? echo $PHP_SELF; ?>" method="POST">
<tr>
<td valign="top"><b><font size="-1">Slug</font></b></td>
<td><input size="50" maxlength="250" type="text" name="slug"></td>
</tr>
<tr>
<td valign="top"><b><font size="-1">Content</font></b></td>
<td><textarea name="content" cols="40" rows="10"></textarea></td>
</tr>
<tr>
<td valign="top"><font size="-1">Contact person</font></td>
<td><input size="50" maxlength="250" type="text" name="contact"></td>
</tr>
<tr>
<td colspan=2><input type="Submit" name="submit" value="Add"></td>
</tr>
</form>
</table>
<?
}
else
{
// form processor code here
}
?>
<!-- page footer - snip -->
Here's what it looks like:
Now, once the administrator enters data into this form and submits it, the same script is called again to process the data (note the presence of the special $PHP_SELF variable in the form's ACTION attribute). Since the $submit variable will now exist, control will transfer to the latter half of the script, which looks like this:
<?
// add.php - add a new press release
?>
<!-- page header - snip -->
<?
if (!$submit)
{
// form display code goes here
}
else
{
// includes
include("../conf.php");
include("../functions.php");
// set up error list array
$errorList = array();
$count = 0;
// validate text input fields
if (!$slug) { $errorList[$count] = "Invalid entry: Slug"; $count++; }
if (!$content) { $errorList[$count] = "Invalid entry: Content"; $count++; }
// set default value for contact person
if (!$contact) { $contact = $def_contact; }
// check for errors
// if none found...
if (sizeof($errorList) == 0)
{
// open database connection
$connection = mysql_connect($host, $user, $pass) or die ("Unable to
connect!");
// select database
mysql_select_db($db) or die ("Unable to select database!");
// generate and execute query
$query = "INSERT INTO news(slug, content, contact, timestamp)
VALUES('$slug', '$content', '$contact', NOW())";
$result = mysql_query($query) or die ("Error in query: $query. " .
mysql_error());
// print result
echo "<font size=-1>Update successful. <a href=list.php>Go back to the
main menu</a>.</font>";
// close database connection
mysql_close($connection);
}
else
{
// errors found
// print as list
echo "<font size=-1>The following errors were encountered: <br>";
echo "<ul>";
for ($x=0; $x<sizeof($errorList); $x++)
{
echo "<li>$errorList[$x]";
}
echo "</ul></font>";
}
}
?>
<!-- page footer - snip -->
Fairly simple, this. The first thing to do is ensure that all
required values are present, and to generate errors if not. These errors are stored in the array $errorList.
<?
// set up error list array
$errorList = array();
$count = 0;
// validate text input fields
if (!$slug) { $errorList[$count] = "Invalid entry: Slug"; $count++; }
if (!$content) { $errorList[$count] = "Invalid entry: Content"; $count++; }
?>
In the event that the contact person field is left empty, a
default value is used; this value is pulled in from the configuration file "conf.php".
<?
// set default value for contact person
if (!$contact) { $contact = $def_contact; }
?>
Once all the data validation is complete, the $errorList
array is checked for entries. If entries are present in this array, a message is displayed listing the errors; if not, an INSERT query is generated to add the data to the database, and a success message is printed to the browser.
<?
// check for errors
// if none found...
if (sizeof($errorList) == 0)
{
// snip
// generate and execute query
$query = "INSERT INTO news(slug, content, contact, timestamp)
VALUES('$slug', '$content', '$contact', NOW())";
$result = mysql_query($query) or die ("Error in query: $query. " .
mysql_error());
// print result
echo "<font size=-1>Update successful. <a href=list.php>Go back to the
main menu</a>.</font>";
// snip
}
else
{
// errors found
// print as list
echo "<font size=-1>The following errors were encountered: <br>";
echo "<ul>";
for ($x=0; $x<sizeof($errorList); $x++)
{
echo "<li>$errorList[$x]";
}
echo "</ul></font>";
}
?>
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