PHP - Rendering dynamic web page through web browser - php

Question

I am new to php and programming,, I have been following a tutorial but I've ran into a problem when trying to display the products onto a web page, This is the code am testing
<?php
if (isset($_GET['id'])) {
include "storescripts/connect_to_mysql.php";
$id = preg_replace('#[^0-9]#i', '', $_GET['id']);
$sql = mysql_query("SELECT * FROM products WHERE id='$id' LIMIT 1");
$productCount = mysql_num_rows($sql);
if ($productCount > 0) {
while($row = mysql_fetch_array($sql)){
$product_name = $row["product_name"];
$price = $row["price"];
$details = $row["details"];
$category = $row["category"];
$subcategory = $row["subcategory"];
$date_added = strftime("%b %d, %Y", strtotime($row["date_added"]));
}
} else {
echo "That item does not exist.";
exit();
}
} else {
echo "Data to render this page is missing.";
exit();
}
mysql_close();
?>
When I try to view the page through my browser I get the message "Data to render this page is missing"
I understand that it''s something to do with
if (isset($_GET['id'])) {
And am assuming maybe it's something to do with the 'id' But I cant work out how to fix it. Any pointers and help would be appreciated, sorry if this seems basic but like I said I am new and cant work this problem out. I've been trying all day
Thanks

Answer 1

Obviously, $_GET['id'] isn't set. If your link was something like http://www.example.com/index.php?id=32, it would be set.
Second, do not use GET/POST variables in queries without sanitising them!
And third, don't use mysql_query in the first place, but PDO or mysqli instead

Answer 2

When you see $_GET it's looking for a parameter in the URL. So:
http://localhost/yourphpscript.php?id=123
...is what it's expecting. Some ID must be defined in the URL.

Answer 3

You could try this code:
<?php
if (isset($_GET['id'])){ //Someone submitted a form or just prepended parameter to link
include "storescripts/connect_to_mysql.php"; //Include script with mysql connection
$id = preg_replace('#[^0-9]#i', '', $_GET['id']); //Sanitize input - remove everything besides numbers
$result = mysql_query("SELECT * FROM products WHERE id='$id' LIMIT 1"); //Execute query. Only 1 product because of LIMIT 1
if (mysql_num_rows($result)==1){ //If the product is found
$product = mysql_fetch_assoc($result) ; //Take the product
foreach ($product as $property => $value){ //Go through each property of product
echo "<div> {$property} : {$value} </div>" ;
}
}
} else {?>
<form method="get" action="<?php $_SERVER['PHP_SELF'] ; ?>">
<input type="text" name="id" />
<input type="submit" value="Submit product ID"/>
</form>
<?php
}
?>
Just ask if you have any questions.

Answer 4

learn to track your id. sanitize and check the url sending the id for correct value passed and again in the begining check the value as in
<?php
echo $_GET['id'];
?>
use this to know what it is your id value