Getting error with prepared statement query - php

Question

I'm facing a problem for several days now, and I'm staring blind at it, and can't seem to find the source myself.
I've made a class to execute my queries. The actual query executing part looks like this:
<?php
public function query( $method, $table, $data, $where_text='', $where_data='' ) {
$this->check_db_status();
$method = strtoupper( $method );
$fieldsArray = array();
$valuesArray = array();
$paramsArray = array();
$format = '';
$queryText = '';
switch( $method ) {
case 'SELECT' :
$queryText = 'SELECT %s FROM ' . $table . ' ';
foreach( $data as $field => $value ) {
$fieldsArray[] = $value;
}
break;
case 'UPDATE' :
$queryText = 'UPDATE ' . $table . ' SET %s ';
foreach( $data as $field => $value ) {
$fieldsArray[] = $field.'=?';
$format .= $this->get_value_type( $value );
$paramsArray[] = $value;
}
break;
case 'DELETE' :
$queryText = 'DELETE FROM ' . $table . ' ';
break;
case 'INSERT' :
$queryText = 'INSERT INTO ' . $table . ' (%s) VALUES (%s) ';
foreach( $data as $field => $value ) {
$fieldsArray[] = $field;
$format .= $this->get_value_type( $value );
$valuesArray[] = '?';
$paramsArray[] = $value;
}
break;
default :
$this->get_error( 'Error in method switch' );
break;
}
if( $where_text ) {
$queryText .= $where_text;
if( $where_data ) {
foreach( $where_data as $value ) {
$format .= $this->get_value_type( $value );
$paramsArray[] = $value;
}
}
}
$fields = implode( ',', $fieldsArray );
$values = implode( ',', $valuesArray );
$query = sprintf( $queryText, $fields, $values );
// DEBUG
echo '<pre>';
echo 'query: ' . $query . '<br />
echo 'format: ' .' . $format . '<br />';
print_r( $paramsArray );
echo '</pre>';
$stmt = $this->mysqli->prepare( $query );
if( $stmt === false or $stmt == NULL ) {
$this->get_error( 'Error while preparing the statement' );
}
if( $format and $paramsArray )
call_user_func_array( 'mysqli_stmt_bind_param', array_merge( array( $stmt, $format ), $paramsArray ) );
if( $stmt->execute() ) {
$result = 0;
switch( $method ) {
case 'INSERT' :
$result = ($stmt->insert_id) ? $stmt->insert_id : true;
break;
case 'UPDATE' :
case 'DELETE' :
$result = ($stmt->affected_rows) ? $stmt->affected_rows : true;
break;
case 'SELECT' :
$meta = $stmt->result_metadata();
$fields = $result = array();
while ($field = $meta->fetch_field()) {
$var = $field->name;
$$var = null;
$fields[$var] = &$$var;
}
call_user_func_array(array($stmt,'bind_result'),$fields);
$i = 0;
while( $stmt->fetch() ) {
$result[$i] = array();
foreach( $fields as $k => $v)
$result[$i][$k] = $v;
$i++;
}
break;
}
$stmt->close();
$this->query_cnt++;
return $result;
}
else {
$this->get_error();
}
}
?>
Now I'm trying to make an other class to store my sessions in my own database. The write function looks like this:
<?php
public function write_session( $session_id, $session_data ) {
$query = $this->sql->query( 'INSERT', 'sessions', array( 'ses_id'=>$session_id, 'ses_time'=>time(), 'ses_start'=>time(), 'ses_data'=>$session_data, 'ses_check'=>$this->check ), 'ON DUPLICATE KEY UPDATE ses_time=?, ses_data=?', array(time(),$session_data));
if($query) {
return true;
}
else {
return false;
}
}
?>
I keep getting this error:
Warning: mysqli::prepare() [mysqli.prepare]: Couldn't fetch mysqli in /.../class.db.php on line 124
Line 124 is the line with $stmt = $this->mysqli->prepare( $query );. It is triggered by the first line of the write_session.
If put in a debug part in the database class to show the query, it gives this output:
query: INSERT INTO sessions (ses_id,ses_time,ses_start,ses_data,ses_check) VALUES (?,?,?,?,?) ON DUPLICATE KEY UPDATE ses_time=?, ses_data=?
format: [siissis]
Array
(
[0] => a98696a8416fc898f2c07e05f39735dc
[1] => 1402201705
[2] => 1402201705
[3] => test|s:11:"someValuess";
[4] => 40b17cb572d9bf5eaadad99b7904e0a4889a31d0
[5] => 1402201705
[6] => test|s:11:"someValuess";
)
Which seems fine to me.... what am I overlooking?
Edit
Table definition of sessions:
sessions (
ses_id varchar(32) NOT NULL,
ses_time int(11) NOT NULL,
ses_start int(11) NOT NULL,
ses_data text NOT NULL,
ses_check varchar(40) NOT NULL,
PRIMARY KEY (ses_id)
)

Answer 1

A pointed out in the link provided in the comments, your problem appears to be
4. You mixed OOP and functional calls to the database object.
Specifically, you use a mysqli object here
$stmt = $this->mysqli->prepare( $query );
But then proceed to make a functional mysqli call here
if( $format and $paramsArray )
call_user_func_array( 'mysqli_stmt_bind_param', array_merge( array( $stmt, $format ), $paramsArray ) );
So try replacing the code above with its corresponding OOP version
if($format and $paramsArray) {
$stmt->bind_param($format,$paramsArray);
}
Also replace
call_user_func_array(array($stmt,'bind_result'),$fields);
With
$stmt->bind_param($format,$fields);
http://www.php.net//manual/en/mysqli-stmt.bind-param.php
Implement __wakeup
Another possibility is that your db connection may have been closed due to serialization. Try reconnecting by implementing __wakup i.e.
public function __wakeup()
{
$this->mysqli = new mysqli('localhost', 'my_user', 'my_password', 'my_db');
}