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$_GET and $_POST methods
ОглавлениеHere you will learn how to use the request variables $_GET and $_POST. These variables provide you with different ways to transfer data from one web page to another. Let’s look at the two methods, starting with GET. First, let’s create a simple HTML form.
$_GET []
<html>
<head>
<title> Form Methods
</title>
</head>
<body>
<form method=“get” action="actionpage.php”>
<p> <input type=“text” name=“greeting” size=“15”> </p>
<p> <input type=“text” name=“name” size=“15”> </p>
<p> <input type=“submit” name=“submit” value=“Salutation”> </p>
</form>
</body>
</html>
Save it as a form_methods.php file in the Apache htdocs/post folder created by you.
And now, we’ll create a actionpage.php file for the Output: data transferred from the form.
<?
echo $_GET [‘greeting’];
echo $_GET [‘name’];
echo”! ”;
?>
Save this file in the same directory as the form_methods.php file. This form looks like the following:
Figure 1. A simple HTML form
Let us enter a greeting and a name and click the Salutation button.
You can see that the data sent from a form with the GET method is displayed in the browser’s address bar:
http://localhost/post/formoutputpage.php? <=>
greeting=Hello&name=Emily&submit=Salutation
The Output web page displays Hello Emily!
$_POST []
Now let’s use the POST method instead of the GET method. Edit form_method.php form.
<html>
<head>
<title> Form Methods </title>
</head>
<body>
<form method=“post” action="formoutputpage.php”>
<p> <input type=“text” name=“greeting” size=“15”> </p>
<p> <input type=“text” name=“name” size=“15”> </p>
<p> <input type=“submit” name=“submit” value=“Salutation”> </p>
</form>
</body>
</html>
Edit formoutputpage.php file as follow:
<?
echo $_POST [‘greeting’];
echo “”. $_POST [‘name’];
echo”! ”;
?>
The browser address bar displays formoutputpage.php, but no data transferred using the POST method is visible, so the web page output remains the same:
Hello Emily!
You don’t have to create a second page to read data submitted with form because it is possible to submit the form to the same page. To do this use super global $_SERVER [“PHP_SELF”].
<?php
$self=$_SERVER [“PHP_SELF”];
$greeting=“”;
$name=“”;
If (isset ($_POST [‘greeting’]))
$greeting=$_POST [‘greeting’];
If (isset ($_POST [‘name’]))
$name=$_POST [‘name’];
if (($name!=“”) && ($greeting!=“”))
echo $greeting.””. $name;
?>
<html>
<head>
<title> Form Methods
</title>
</head>
<body>
<?php
print (”<form method=“post” action=“”. $self.””>”);
?>
<p> <input type=“text” name=“greeting”
size=“15”> </p> 21
<p> <input type=“text” name=“name” size=“15”> </p>
<p> <input type=“submit” name=“submit”
value=“Salutation”> </p>
</form>
</body>
</html>
The htmlentities () function
The htmlentities () function is used for security reasons. It converts all characters to HTML entities.
For example, the '<' character will be converted to HTML '<”
If you add the ENT_QUOTES parameter, it will convert double quotes and single quotes to HTML entities.
<?php
$string='<a href="configure-all.com”> Web programming and design </a>”;
echo htmlentities ($string, ENT_QUOTES). "<br>”;
?>
Output (on the browser screen)
<a href="configure-all.com”> Web programming and design </a>.
If you view source you will see HTML characters:
< a href="configure-all.com"> Web programming and design</a> <br>
The filter_var function (since PHP 5.2.0)
The filter_var function validates user input. Read more on the PHP.net website.
http://us.php.net/manual/en/filter.filters.validate.php
The example below validates the email address entered by a user.
<?php
function valid_email ($email) {
// filter_var returns false if email is invalid.
$email=filter_var ($email, FILTER_VALIDATE_EMAIL);
If (!$email)
echo “Email is invalid!”;
else
echo $email;
}
valid_email ("master@configure-all.com”);
echo "<br>”;
valid_email ("masterconfigure-all.com”);
?>
Output:
1. master@configure-all.com
2. “Email is not valid!”
When you pass an invalid email address to filter_var function (at the second echo) an empty string is returned.
Read about all exiting validate and sanitize filters on the PHP.net website.
Validate filters
FILTER_VALIDATE_BOOLEAN
FILTER_VALIDATE_EMAIL
FILTER_VALIDATE_FLOAT
FILTER_VALIDATE_INT
FILTER_VALIDATE_IP
FILTER_VALIDATE_REGEXP
FILTER_VALIDATE_URL
Sanitize filters
$email=‘maste” rconfi <> gur/e-all.com’;
echo filter_var ($email, FILTER_SANITIZE_EMAIL);
Output: master@configure-all.com
FILTER_SANITIZE_EMAIL
FILTER_SANITIZE_ENCODED
FILTER_SANITIZE_MAGIC_QUOTES
FILTER_SANITIZE_NUMBER_FLOAT
FILTER_SANITIZE_NUMBER_INT
FILTER_SANITIZE_SPECIAL_CHARS
FILTER_SANITIZE_FULL_SPECIAL_CHARS
FILTER_SANITIZE_STRING
FILTER_SANITIZE_STRIPPED
FILTER_SANITIZE_URL
FILTER_UNSAFE_RAW
Let us return to accessing the variables value submitted to the form using the POST method.
If (isset ($_POST [‘lastname’]))
$lastname= ($_POST [‘lastname’];
If you didn’t declare variables before the if statement, you will receive a notice displayed by PHP:
“Notice: Undefined variable name in C:\Apache2.2\htdocs\test\post.php on line 9”
The notice is displayed because the $lastname variable will be defined inside the if statement only. To have it defined anyplace on the page, you must declare it outside the if statement.
$lastname=“”;
if (isset ($_POST [‘lastname’]))
$lastname= ($_POST [‘lastname’];
Now, no notice message will be displayed.
