Requirements:
1. Access to a server with PHP installed
2. A text editor to create the files
3. A working knowledge of HTML
A simple example on a method to handle forms (along with errors).
The error handling will be basic – just checking for empty inputs. A tutorial for validation will be available in the future.
Nothing will really be done with the information – no database connections or emails. The input will just be reprinted on the screen if successful.
The Files
I will make use of a modified
index.php and
page.php from the tutorial “My First PHP”. There is also a third file attached to this tutorial called
form.php.
The Form
In the form.php file, we need to create the following function to create the form:
PHP Code:
function form_DrawForm($f, $e, $a)
{
// draws a form on the page
// $f = previous form data
// $e = errors in previous submission
// $a = action for the form
?>
<form action='<?php echo $a; >' method='post'>
<!-- action = file used to handle the form -->
<!-- method = transmission method of form data
post = hidden in HTTP request
get = coded in the URL and is visible -->
<?php
if (isset($e['username']))
{
// if there is a problem with the previous input, then try again
// and highlight the problem
echo "<span style='color : #CC0000; font-weight : bold'>";
echo "You must enter a username";
echo "</span><br />\r\n";
}
?>
<input type='text' name='username' id='form_text_username'
class='form_text_input' value='<?php echo $f['username']; ?>' />
<br />
<button type='submit' name='submit' value='submit'>Submit</button>
</form>
<?php
}
Initialising the Form
Code:
<input type='text' name='username' id='form_text_username'
class='form_text_input' value='<?php echo $f['username']; ?>' />
We can create default values for the first presentation of the form (ideal for user profile configuration or similar).
All we need is another function to do this. This function will return an array of values:
PHP Code:
function form_InitForm()
{
// initialises the inputs for the form
$f['username'] = ""; // empty string for the initial value
return $f;
}
Checking the Form
This function goes through the input information and returns an array of errors if they are found. Remember that this is only a simple validation of the input which only requires that something be entered – tutorials on more complex validation methods will be written soon.
PHP Code:
function form_CheckForm($f)
{
// validates the inputs of the form
// $f = form inputs
$e = array();
if ($f['username'] == "")
{
$e['errors'] = true; // this must be set on all error conditions
$e['username'] = true; // allows us to specify an error within the username
}
return $e;
}
Handling the Form
PHP Code:
function form_HandleForm($f)
{
// performs the actions of a successful form input
echo "Welcome ". $f['username'];
}
Scoutt has already written an email handler tutorial, and a database tutorial is not long in arriving to HTML Forums.
Putting It All Together
Okay, we got the functions… now what about the actual script?
Well, first off, we will need to
include the file
form.php into the script (
index.php):
PHP Code:
include "includes/index.php";
We’ll do the messy stuff like validation and/or initialisation before we send any content to the browser:
PHP Code:
if (isset($_POST['submit']))
{
// checks if a form has been submitted already
// the form is using the POST method, so we check the $_POST array
$formdata = $_POST;
$errors = form_CheckForm($formdata); // validates the inputs
}
else
{
$formdata = form_InitForm(); // initialises the form
$errors = array(); // empty array
}
So the above code goes right before the
page_Header() function used in the script.
The rest of the code goes into the content section (between
page_MainStart() and
page_MainFinish()):
PHP Code:
if ((!isset($_POST['submit'])||(isset($errors['errors']))
{
// if no previous form has been submitted, or an error is found
form_DrawForm($formdata, $errors, "index.php");
}
else
{
form_HandleForm($formdata);
}
Well, there you go – a simple way to deal with forms.
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