dynamic mysqli prepared statement fails - php

Question

I am trying to write a very small abstraction layer for my mysqli connection and have run into a problem.
Since I am maintaining older code I need to get an associative array from my query as this is the way the code has been set up and therefor less work for me once this works...
This function does work with all kinds of queries(not just select)...
my function I wrote is this:
function connectDB($query,$v=array()) {
$mysqli = new mysqli(HOST,USER,PW,DATABASE);
if($res=$mysqli->prepare($query)) {
//dynamically bind all $v
if($v) {
$values=array($v[0]);
for($i=1; $i<count($v); $i++) {
${'bind'.$i}=$v[$i];
$values[]=&${'bind'.$i};
}
call_user_func_array(array($res,'bind_param'),$values);
}
$res->execute();
//bind all table rows to result
if(strtolower(substr($query,0,6))=="select") {
$fields=array();
$meta=$res->result_metadata();
while($field=$meta->fetch_field()) {
${$field->name}=null;
$fields[$field->name]=&${$field->name};
}
call_user_func_array(array($res,"bind_result"),$fields);
//return associative array
$results = array();
$i=0;
while($res->fetch()) {
$results[$i]=array();
foreach($fields as $k => $v) $results[$i][$k] = $v;
$i++;
}
}
else {
$results=$mysqli->affected_rows;
if($mysqli->affected_rows<1) $results=$mysqli->info;
}
$res->close();
}
$mysqli->close();
return $results;
}
so if I call:
$MySqlres=connectDB("select * from `modx_events` events limit 1");
var_dump($MySqlres);
I get a nice associative array with the content of my select.
Now unfortunately the following mysql query will return NULL as a value to all of it's array keys:
$MySqlres=connectDB("select *, events.`id` as `ID`,venues.`name` as `venueName`,
venues.`suburb` as `venueSuburb`,venues.`advertiser` as `venueAdvertiser`
from `modx_events` events left join `modx_venues` venues on events.`venue`=venues.`id`
where events.`id`!='e' order by events.`start_date` asc, venues.`name` limit 1");
(the same query runs as pure SQL and will return the correct values)
Any idea what this could be? Does my associative array function fail? Is there something wrong with the way I implemented the query?
ps: PDO is not an option and mysqlnd is not installed... :(
ADDED QUESTION
is this too much of overhead just to preserve the associative array return? Should I go with $res->fetch_object() instead?

Answer 1

Mysqli is very poor with dynamic prepared statements, which makes small abstraction layer creation a nightmare.
I strongly suggest you to switch to PDO or get rid of prepared statements and create a regular query based on the manually handled placeholders (preferred).
As a palliative patch you can try to use get_result() function which will return a regular result variable which you can traverse usual way with fetch_assoc()
But it works only with mysqlnd builds.
Also note that creating mysqli object for the every query is a big no-no.
Create it once and then assign it in your query function using global $mysqli;
is this too much of overhead
I don't understand what overhead you're talking about

Answer 2

I just fixed the function.
Perhaps this is interesting for someone else:
function connectDB($mysqli,$query,$v=array()) {
if($mysqli->connect_errno) {
return array('error'=>'Connect failed: '.$mysqli->connect_error); //error handling here
exit();
}
if(substr_count($query,"?")!=strlen($v[0])) {
return array('error'=>'placeholders and replacements are not equal! placeholders:'.substr_count($query,"?").' replacements:'.strlen($v[0]).' ('.$v[0].')'); //error handling here...
exit();
}
if($res=$mysqli->prepare($query)) {
//dynamically bind all $v
if($v) {
$values=array($v[0]);
for($i=1; $i<count($v); $i++) {
${'bind'.$i}=$v[$i];
$values[]=&${'bind'.$i};
}
call_user_func_array(array($res,'bind_param'),$values);
}
$res->execute();
//bind all table rows to result
if(strtolower(substr($query,0,6))=="select") {
$field=$fields=$tempRow=array();
$meta=$res->result_metadata();
while($field=$meta->fetch_field()) {
$fieldName=$field->name;
$fields[]=&$tempRow[$fieldName];
}
$meta->free_result();
call_user_func_array(array($res,"bind_result"),$fields);
//return associative array
$results=array();
$i=0;
while($res->fetch()) {
$results[$i]=array();
foreach($tempRow as $k=>$v) $results[$i][$k] = $v;
$i++;
}
$res->free_result();
}
else { //return infos about the query
$results["affectedRows"]=$mysqli->affected_rows;
$results["info"]=$mysqli->info;
$results["insertID"]=$mysqli->insert_id;
}
$res->close();
}
return $results;
}
cheers