Sunday 22 May 2016

php - Fatal error: Call to a member function fetch_assoc() on a non-object




I'm trying to execute a few queries to get a page of information about some images. I've written a function



function get_recent_highs($view_deleted_images=false)
{
$lower = $this->database->conn->real_escape_string($this->page_size * ($this->page_number - 1));
$query = "SELECT image_id, date_uploaded FROM `images` ORDER BY ((SELECT SUM( image_id=`images`.image_id ) FROM `image_votes` AS score) / (SELECT DATEDIFF( NOW( ) , date_uploaded ) AS diff)) DESC LIMIT " . $this->page_size . " OFFSET $lower"; //move to database class
$result = $this->database->query($query);
$page = array();

while($row = $result->fetch_assoc())
{
try
{
array_push($page, new Image($row['image_id'], $view_deleted_images));
}
catch(ImageNotFoundException $e)
{
throw $e;
}

}
return $page;
}


that selects a page of these images based on their popularity. I've written a Database class that handles interactions with the database and an Image class that holds information about an image. When I attempt to run this I get an error.



Fatal error: Call to a member function fetch_assoc() on a non-object



$result is a mysqli resultset, so I'm baffled as to why this isn't working.


Answer



That's because there was an error in your query. MySQli->query() will return false on error. Change it to something like::



$result = $this->database->query($query);
if (!$result) {
throw new Exception("Database Error [{$this->database->errno}] {$this->database->error}");
}



That should throw an exception if there's an error...


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