Databases Reference
In-Depth Information
When the user types in information and clicks the Submit button, the form passes the
data to the script specified in the form
action
attribute; in our example, the data is sent
to the script
process.php
.
Our form has three input fields:
username
,
password
, and
submit
. Since the form submits
the data using the
POST
method, we can look inside the
$_POST
superglobal array in
process.php
to access the corresponding values as
$_POST["username"]
,
$_POST["password"]
, and
$_POST["submit"]
. The data from the submit field will just be
Log In
(as specified in the form), and this field isn't very useful; however, it's important
to know that it exists.
Using One Script for the Form and for Processing
It's common to use a single PHP script to both generate the HTML form and to receive
the submitted form data. When the user submits the form, the browser sends the user
data along with the request. The script can decide what to do by checking for the user
data: if there's no user data, it generates and sends the HTML login form; if there is
some user data, it processes it. We can use the
count( )
function to count the number
of entries in the
$_POST
array. If the count is nonzero, we know that some data has been
submitted using the
POST
method:
// If the number of elements in the $_POST array is nonzero...
if(count($_POST))
{
// Process form data
}
// otherwise...
else
{
// Generate HTML form
}
?>
We can improve this code a bit. If a user clicks the Submit button without typing in a
username or password, the
$_POST
array will still contain one item: the data from the
Submit button itself (
$_POST["submit"]
). We can try to read the username and password
from the
$_POST
array; if the form has not been submitted, this array will be uninitialized,
and so the username and password entries will be empty. The username and password
can also be left blank by the user. In either case, our script will detect an empty username
or password, and will show the form. If the username and password aren't empty, the
script will process the data and try to log the user in to the application:
// Pre-process the authentication data from the form for security
// and assign the username and password to local variables
if(count($_POST))
{
$username = clean($_POST["username"], 30);
$password = clean($_POST["password"], 30);
}
