Re: Undefined index error
"Undefined index" means that you're trying to access an element in an array that does not exist. So, what's on line 16?
PHP Code:
$get_item_sql = "SELECT c.id as cat_id, c.cat_title, si.item_title, si.item_price, si.item_desc, si.item_image FROM store_items AS si LEFT JOIN store_categories AS c on c.id = si.cat_id WHERE si.id = '".$_GET["item_id"]."'";
So "item_id" is not a defined index in the $_GET array. You can of course populate it by adding to the URL's query string ("?item_id=x"), but you should also check for its being empty:
PHP Code:
if(!isset($_GET["item_id"])){
//populate with a default value,
//or do something else
}
And you should absolutely never put a variable from $_GET into an unprepared SQL statement without sanitization.
Re: Undefined index error
Hello,
Thanks for your response to my message. I do not normally like to be spoon-fed. When you say, "Undefined index" means that you're trying to access an element in an array that does not exist. I fully understand that. But anything else I do not understand its implementation. "You can of course populate it by adding to the URL's query string ("?item_id=x"), but you should also check for its being empty:"
It is like I am making a mess of it now with my attempt. Could you make this correction to my code that I posted earlier and see if it works, please?
I will really appreciate your help.
Menre
Re: Undefined index error
Your code is failing because $_GET['item_id'] doesn't exist. In order for it to exist, you need to put a query string variable in the URL: http://www.yourdomain.com/pageName.php?item_id=3
Since you cannot ensure that your page will always be accessed with the proper query string, you should check for the presence of $_GET variables before attempting to use them in your code. You can do this with the isset() function, like so:
PHP Code:
//set a default value for our variable:
$item_id = 1;
if(isset($_GET['item_id'])){
//$_GET['item_id] exists,
//so overwrite the default value of the variable with the given value from $_GET:
$item_id = $_GET['item_id'];
}
//rather than using the $_GET variable in our query, use the variable we set up:
$get_item_sql = "SELECT c.id as cat_id, c.cat_title, si.item_title, si.item_price, si.item_desc, si.item_image FROM store_items AS si LEFT JOIN store_categories AS c on c.id = si.cat_id WHERE si.id = '".$item_id."'";
Re: Undefined index error
I would put the query within the if (isset(...)) block as well since the whole procedure is dependent on that variable being present.
Also, please take note of Samba's advice here:
Quote:
absolutely never put a variable from $_GET into an unprepared SQL statement without sanitization
Since you're using mysqli already, make use of its prepared statement support.
Look at the examples here:
http://php.net/manual/en/mysqli.prepare.php
Notice how they use the bind_param function. This separates the data from the SQL, so that the semantics of the query cannot be altered by the data.
Re: Undefined index error
Hi Everyone,
Thanks for your advice and responses. They all really helped me out. it is working now. I did it the way you adised and everything is now fine. There were a few other errors and I was able to fix those ones. The full working code is placed below.
Code:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Online storefront: Just for baseball lovers.</title>
</head>
<body>
<?php
//connect to the database here. Note, if you have a database already and you know the name, you can add it after the password argument.
$mysqli = mysqli_connect('localhost','root','', 'eshop');
//echo "I am well connected";
$display_block = "<h1>Online store for baseball enthusiasts</h1>";
//we set a default value for our variable
$item_id = 1;
if (isset($_GET['item_id'])) {
//we know that item_id exists
//we now overide the default value of the variable with the given value from $_GET
$item_id = $_GET['item_id'];
}
//validate item
$get_item_sql = "SELECT c.id as cat_id, c.cat_title, si.item_title, si.item_price, si.item_desc, si.item_image FROM store_items AS si LEFT JOIN store_categories AS c on c.id = si.cat_id WHERE si.id = '".$item_id."'";
//here we display the result
$get_item_res = mysqli_query($mysqli, $get_item_sql) or die(mysqli_error($mysqli));
if (mysqli_num_rows($get_item_res) < 1) {
//invalid item
$display_block .= "<p><em>Invalid item selction.</em></p>";
}
else {
//valid item, get info
while ($item_info = mysqli_fetch_array($get_item_res)) {
$cat_id = $item_info['cat_id'];
$cat_title = strtoupper(stripslashes($item_info['cat_title']));
$item_title = stripslashes($item_info['item_title']);
$item_price = $item_info['item_price'];
$item_desc = stripslashes($item_info['item_desc']);
$item_image = $item_info['item_image'];
}
//here make breadcrumb trail
$display_block .= "<p><strong><em>You are viewing:</em><br/>
<a href=\"seestore.php?cat_id=".$cat_id."\">".$cat_title."</a>> ".$item_title."</strong></p>
<table cellpadding=\"3\" cellspacing=\"3\">
<tr>
<td valign=\"middle\" align=\"center\">
<img src=\"".$item_image."\"/></td>
<td valign=\"middle\"><p><strong>Description:</strong><br/>".
$item_desc."</p>
<p><strong>Price:</strong> \$".$item_price."</p>";
//free result
mysqli_free_result($get_item_res);
//get colors
$get_colors_sql = "SELECT item_color FROM store_item_color WHERE item_id = '".$item_id."' ORDER BY item_color";
//now show the results for get color
$get_color_res = mysqli_query($mysqli, $get_colors_sql)
or die(mysqli_error($mysqli));
if (mysqli_num_rows($get_color_res) > 0) {
$display_block .= "<p><strong>Available Colors:</strong><br/>";
while ($colors = mysqli_fetch_array($get_color_res)) {
$item_color = $colors['item_color'];
$display_block .= $item_color."<br/>";
}
}
//free result
mysqli_free_result($get_color_res);
//get sizes
$get_sizes_sql = "SELECT item_size FROM store_item_size WHERE item_id = '".$item_id."' ORDER BY item_size";
//we show the rsult get sizes below
$get_sizes_res = mysqli_query($mysqli,$get_sizes_sql) or die(mysqli_error($mysqli));
if (mysqli_num_rows($get_sizes_res) > 0) {
$display_block .= "<p><strong>Available Sizes:</strong><br/>";
while ($sizes = mysqli_fetch_array($get_sizes_res)) {
$item_size = $sizes['item_size'];
$display_block .= $item_size."<br/>";
}
}
//free result
mysqli_free_result($get_sizes_res);
$display_block .= "
</td>
</tr>
</table>";
}
?>
<?php echo $display_block;?>
</body>
</html>
It is always a pleasure learning from PROS like you. Once again, thanks.
Menre
