MySQLi Wrapper: fetch_field() on a non-object - php

Question

I'm using the following wrapper:
<?php
/**
* MysqliDb Class
*
* #category Database Access
* #package MysqliDb
* #author Jeffery Way <jeffrey#jeffrey-way.com>
* #author Josh Campbell <jcampbell#ajillion.com>
* #copyright Copyright (c) 2010
* #license http://opensource.org/licenses/gpl-3.0.html GNU Public License
* #version 1.1
**/
class MysqliDb
{
/**
* Static instance of self
*
* #var MysqliDb
*/
protected static $_instance;
/**
* MySQLi instance
*
* #var mysqli
*/
protected $_mysqli;
/**
* The SQL query to be prepared and executed
*
* #var string
*/
protected $_query;
/**
* An array that holds where conditions 'fieldname' => 'value'
*
* #var array
*/
protected $_where = array();
/**
* Dynamic type list for where condition values
*
* #var array
*/
protected $_whereTypeList;
/**
* Dynamic type list for table data values
*
* #var array
*/
protected $_paramTypeList;
/**
* Dynamic array that holds a combination of where condition/table data value types and parameter referances
*
* #var array
*/
protected $_bindParams = array(''); // Create the empty 0 index
/**
* #param string $host
* #param string $username
* #param string $password
* #param string $db
* #param int $port
*/
public function __construct($host, $username, $password, $db, $port = NULL)
{
if($port == NULL)
$port = ini_get('mysqli.default_port');
$this->_mysqli = new mysqli($host, $username, $password, $db, $port)
or die('There was a problem connecting to the database');
$this->_mysqli->set_charset('utf8');
self::$_instance = $this;
}
/**
* A method of returning the static instance to allow access to the
* instantiated object from within another class.
* Inheriting this class would require reloading connection info.
*
* #uses $db = MySqliDb::getInstance();
*
* #return object Returns the current instance.
*/
public static function getInstance()
{
return self::$_instance;
}
/**
* Reset states after an execution
*
* #return object Returns the current instance.
*/
protected function reset()
{
$this->_where = array();
$this->_bindParams = array(''); // Create the empty 0 index
unset($this->_query);
unset($this->_whereTypeList);
unset($this->_paramTypeList);
}
/**
* Pass in a raw query and an array containing the parameters to bind to the prepaird statement.
*
* #param string $query Contains a user-provided query.
* #param array $bindParams All variables to bind to the SQL statment.
*
* #return array Contains the returned rows from the query.
*/
public function rawQuery($query, $bindParams = null)
{
$this->_query = filter_var($query, FILTER_SANITIZE_STRING);
$stmt = $this->_prepareQuery();
if (is_array($bindParams) === true) {
$params = array(''); // Create the empty 0 index
foreach ($bindParams as $prop => $val) {
$params[0] .= $this->_determineType($val);
array_push($params, $bindParams[$prop]);
}
call_user_func_array(array($stmt, 'bind_param'), $this->refValues($params));
}
$stmt->execute();
$this->reset();
return $this->_dynamicBindResults($stmt);
}
/**
*
* #param string $query Contains a user-provided select query.
* #param int $numRows The number of rows total to return.
*
* #return array Contains the returned rows from the query.
*/
public function query($query, $numRows = null)
{
$this->_query = filter_var($query, FILTER_SANITIZE_STRING);
$stmt = $this->_buildQuery($numRows);
$stmt->execute();
$this->reset();
return $this->_dynamicBindResults($stmt);
}
/**
* A convenient SELECT * function.
*
* #param string $tableName The name of the database table to work with.
* #param integer $numRows The number of rows total to return.
*
* #return array Contains the returned rows from the select query.
*/
public function get($tableName, $numRows = null)
{
$this->_query = "SELECT * FROM $tableName";
$stmt = $this->_buildQuery($numRows);
$stmt->execute();
$this->reset();
return $this->_dynamicBindResults($stmt);
}
/**
*
* #param <string $tableName The name of the table.
* #param array $insertData Data containing information for inserting into the DB.
*
* #return boolean Boolean indicating whether the insert query was completed succesfully.
*/
public function insert($tableName, $insertData)
{
$this->_query = "INSERT into $tableName";
$stmt = $this->_buildQuery(null, $insertData);
$stmt->execute();
$this->reset();
return ($stmt->affected_rows > 0 ? $stmt->insert_id : false);
}
/**
* Update query. Be sure to first call the "where" method.
*
* #param string $tableName The name of the database table to work with.
* #param array $tableData Array of data to update the desired row.
*
* #return boolean
*/
public function update($tableName, $tableData)
{
$this->_query = "UPDATE $tableName SET ";
$stmt = $this->_buildQuery(null, $tableData);
$stmt->execute();
$this->reset();
return ($stmt->affected_rows > 0);
}
/**
* Delete query. Call the "where" method first.
*
* #param string $tableName The name of the database table to work with.
* #param integer $numRows The number of rows to delete.
*
* #return boolean Indicates success. 0 or 1.
*/
public function delete($tableName, $numRows = null)
{
$this->_query = "DELETE FROM $tableName";
$stmt = $this->_buildQuery($numRows);
$stmt->execute();
$this->reset();
return ($stmt->affected_rows > 0);
}
/**
* This method allows you to specify multipl (method chaining optional) WHERE statements for SQL queries.
*
* #uses $MySqliDb->where('id', 7)->where('title', 'MyTitle');
*
* #param string $whereProp The name of the database field.
* #param mixed $whereValue The value of the database field.
*
* #return MysqliDb
*/
public function where($whereProp, $whereValue)
{
$this->_where[$whereProp] = $whereValue;
return $this;
}
/**
* This methods returns the ID of the last inserted item
*
* #return integer The last inserted item ID.
*/
public function getInsertId()
{
return $this->_mysqli->insert_id;
}
/**
* Escape harmful characters which might affect a query.
*
* #param string $str The string to escape.
*
* #return string The escaped string.
*/
public function escape($str)
{
return $this->_mysqli->real_escape_string($str);
}
/**
* This method is needed for prepared statements. They require
* the data type of the field to be bound with "i" s", etc.
* This function takes the input, determines what type it is,
* and then updates the param_type.
*
* #param mixed $item Input to determine the type.
*
* #return string The joined parameter types.
*/
protected function _determineType($item)
{
switch (gettype($item)) {
case 'NULL':
case 'string':
return 's';
break;
case 'integer':
return 'i';
break;
case 'blob':
return 'b';
break;
case 'double':
return 'd';
break;
}
return '';
}
/**
* Abstraction method that will compile the WHERE statement,
* any passed update data, and the desired rows.
* It then builds the SQL query.
*
* #param int $numRows The number of rows total to return.
* #param array $tableData Should contain an array of data for updating the database.
*
* #return mysqli_stmt Returns the $stmt object.
*/
protected function _buildQuery($numRows = null, $tableData = null)
{
$hasTableData = is_array($tableData);
$hasConditional = !empty($this->_where);
// Did the user call the "where" method?
if (!empty($this->_where)) {
// if update data was passed, filter through and create the SQL query, accordingly.
if ($hasTableData) {
$pos = strpos($this->_query, 'UPDATE');
if ($pos !== false) {
foreach ($tableData as $prop => $value) {
// determines what data type the item is, for binding purposes.
$this->_paramTypeList .= $this->_determineType($value);
// prepares the reset of the SQL query.
$this->_query .= ($prop . ' = ?, ');
}
$this->_query = rtrim($this->_query, ', ');
}
}
//Prepair the where portion of the query
$this->_query .= ' WHERE ';
foreach ($this->_where as $column => $value) {
// Determines what data type the where column is, for binding purposes.
$this->_whereTypeList .= $this->_determineType($value);
// Prepares the reset of the SQL query.
$this->_query .= ($column . ' = ? AND ');
}
$this->_query = rtrim($this->_query, ' AND ');
}
// Determine if is INSERT query
if ($hasTableData) {
$pos = strpos($this->_query, 'INSERT');
if ($pos !== false) {
//is insert statement
$keys = array_keys($tableData);
$values = array_values($tableData);
$num = count($keys);
// wrap values in quotes
foreach ($values as $key => $val) {
$values[$key] = "'{$val}'";
$this->_paramTypeList .= $this->_determineType($val);
}
$this->_query .= '(' . implode($keys, ', ') . ')';
$this->_query .= ' VALUES(';
while ($num !== 0) {
$this->_query .= '?, ';
$num--;
}
$this->_query = rtrim($this->_query, ', ');
$this->_query .= ')';
}
}
// Did the user set a limit
if (isset($numRows)) {
$this->_query .= ' LIMIT ' . (int)$numRows;
}
// Prepare query
$stmt = $this->_prepareQuery();
// Prepare table data bind parameters
if ($hasTableData) {
$this->_bindParams[0] = $this->_paramTypeList;
foreach ($tableData as $prop => $val) {
array_push($this->_bindParams, $tableData[$prop]);
}
}
// Prepare where condition bind parameters
if ($hasConditional) {
if ($this->_where) {
$this->_bindParams[0] .= $this->_whereTypeList;
foreach ($this->_where as $prop => $val) {
array_push($this->_bindParams, $this->_where[$prop]);
}
}
}
// Bind parameters to statment
if ($hasTableData || $hasConditional) {
call_user_func_array(array($stmt, 'bind_param'), $this->refValues($this->_bindParams));
}
return $stmt;
}
/**
* This helper method takes care of prepared statements' "bind_result method
* , when the number of variables to pass is unknown.
*
* #param mysqli_stmt $stmt Equal to the prepared statement object.
*
* #return array The results of the SQL fetch.
*/
protected function _dynamicBindResults(mysqli_stmt $stmt)
{
$parameters = array();
$results = array();
$meta = $stmt->result_metadata();
$row = array();
while ($field = $meta->fetch_field()) {
$row[$field->name] = null;
$parameters[] = & $row[$field->name];
}
call_user_func_array(array($stmt, 'bind_result'), $parameters);
while ($stmt->fetch()) {
$x = array();
foreach ($row as $key => $val) {
$x[$key] = $val;
}
array_push($results, $x);
}
return $results;
}
/**
* Method attempts to prepare the SQL query
* and throws an error if there was a problem.
*
* #return mysqli_stmt
*/
protected function _prepareQuery()
{
if (!$stmt = $this->_mysqli->prepare($this->_query)) {
trigger_error("Problem preparing query ($this->_query) " . $this->_mysqli->error, E_USER_ERROR);
}
return $stmt;
}
/**
* Close connection
*/
public function __destruct()
{
$this->_mysqli->close();
}
/**
* #param array $arr
*
* #return array
*/
protected function refValues($arr)
{
//Reference is required for PHP 5.3+
if (strnatcmp(phpversion(), '5.3') >= 0) {
$refs = array();
foreach ($arr as $key => $value) {
$refs[$key] = & $arr[$key];
}
return $refs;
}
return $arr;
}
} // END class
from this URL: https://github.com/ajillion/PHP-MySQLi-Database-Class.
I am using the rawQuery methode. It works fine for SELECT, but when I try to do an UPDATE, the following error shows up: Fatal error: Call to a member function fetch_field() on a non-object in ... on line 419 (that's the 7th line after function _dynamicBindResults). How is that possible?

Answer 1

UPDATE, INSERT, DELETE don't return results like a SELECT query does. Use the implemented update method for update queries:
$updateData = array(
'fieldOne' => 'fieldValue',
'fieldTwo' => 'fieldValue'
);
$db->where('id', int);
$results = $db->update('tableName', $updateData);