Object of class CI_DB_mysqli_result could not be converted to string

$data is an object you cant concatinate string to object.

$query = "SELECT * FROM coursesplace WHERE 1=1"    if(isset($course))     $query .= " AND course=\"$course\" ";    if(isset($location))   $query .= " AND location=\"$location\" ";    if(isset($price))      $query .= " AND price=\"$price\" "; $data = $this->db->query($query);

This will help.i have taken a variable $query and assign string to itaccording to the conditions string is concatenated. And at the end the final query is give to $this->db->query

You can just simply get rid of quotes as

$data = 'SELECT * FROM coursesplace WHERE 1=1';if ($course)    $data .= " AND course='$course' ";if ($location)    $data .= " AND location='$location' ";if ($price)    $data .= " AND price='$price'";$result = $this->db->query($data);return $result->result_array();

Active Records..

public function getinstitution() {    $course = "programming";    $location = "jakarta";    $price = "price2";    $this->db->select('*');    $this->db->from('coursesplace');    $this->db->where('1 = 1');    if ($course != '') {        $this->db->where('course', $course);    }    if ($location != '') {        $this->db->where('location', $location);    }    if ($price != '') {        $this->db->where('price', $price);    }    $data = $this->db->get()->result_array();    return $data;}

Your problem is you're running the query, then trying to ammend the query afterwards.

You should add "SELECT * FROM coursesplace WHERE 1=1" to the $data string, like this;

$data = 'SELECT * FROM coursesplace WHERE 1=1';// Then ammend the $dataif($course)     $data .= "AND course=\"$course\" ";if($location)   $data .= "AND location=\"$location\" ";if($price)      $data .= "AND price=\"$price\"";// Now run the query$query = $this->db->query($data);return $query->result_array();