PHP and Mysqli code error message - php

Question

I have this PHP code which another user on the site was helpful enough to give to me. It is trying to match entries in a database to what the user supplied in a form, and echoing out the picture(s) that match those specifications.
(I define my database info in the first 4 lines, but this site doesn't want to write them out)
// Errors
$error = array();
if (!isset($_POST['submit']))
$error[] = "The form was not set.<br />";
// Here we check if each of the variable are set and have content
if (!isset($_POST['gender']) || strlen($_POST['gender']) == 0)
$error[] = "You must fill the gender field.<br />";
if (!isset($_POST['hair']) || strlen($_POST['hair']) == 0)
$error[] = "You must fill the hair field.<br />";
if (!isset($_POST['height']) || strlen($_POST['height']) == 0)
$error[] = "You must fill the height field.<br />";
if (!isset($_POST['body']) || strlen($_POST['body']) == 0)
$error[] = "You must fill the body field.<br />";
if (empty($error))
{
$con = mysqli_connect($db_host, $db_user, $db_pass, $db_name);
if ($con->connect_error)
die('Connect Error (' . mysqli_connect_errno() . ') '. mysqli_connect_error());
// Here we prepare your query and make sure it is alright
$sql = "SELECT * FROM `table` WHERE gender=? AND hair=? AND height=? AND body=?";
if (!$stmt = $con->prepare($sql))
die('Query failed: (' . $con->errno . ') ' . $con->error);
// Here we define the field types with 'ssss' which means string, string, string
// and also set the fields values
if (!$stmt->bind_param('ssss', $_POST['gender'], $_POST['hair'], $_POST['height'], $_POST['body']))
die('Binding parameters failed: (' . $stmt->errno . ') ' . $stmt->error);
// Now we finally execute the data to update it to the database
// and if it fails we will know
if (!$stmt->execute())
die('Execute failed: (' . $stmt->errno . ') ' . $stmt->error);
// Now we read the data
while ($row = $stmt->fetch_object())
{
$pic = $row->picture;
echo $row->picture, "\n";
}
$stmt->close();
$con->close();
}
else
{
echo "Following error occurred:<br />";
foreach ($error as $value)
{
echo $value;
}
}
?>
I am getting this error message on line 48
Fatal error: Call to undefined method mysqli_stmt::fetch_object() in /home/content/...
which is this line of code:
// Now we read the data
while ($row = $stmt->fetch_object())

Answer 1

You can't fetch the results from a mysqli_stmt object directly. First use get_result to get a mysqli_result object, then use fetch_object on that:
$result = $stmt->get_result();
while ($row = $result->fetch_object())
Note that that only works if you have mysqlnd installed; if not, see the bind_result and fetch methods for a less convenient (but more compatible) approach.