How to use both fetch() and fetchAll() in a PDO wrapper class? - php

Question

How can I alter my PDO wrapper class, so that if I expect a single row result with my query it uses fetch() and if it expects multiple results it uses fetchAll().
Right now, if I have only one result I still have to loop through the result array and that seem pretty unpracticable to me.
Query in the model:
public function doccEdit() {
$id = mysql_real_escape_string($_GET['id']);
$this->result = $GLOBALS['db']->select("creditcards", "id = ?", $id);
print_r($this->result);
}
In the wrapper class:
public function run($sql, $bind="") {
$this->sql = trim($sql);
$this->bind = $this->cleanup($bind);
$this->error = "";
try {
$pdostmt = $this->prepare($this->sql);
if($pdostmt->execute($this->bind) !== false) {
if(preg_match("/^(" . implode("|", array("select", "describe", "pragma")) . ") /i", $this->sql))
return $pdostmt->fetchall(PDO::FETCH_OBJ);
elseif(preg_match("/^(" . implode("|", array("delete", "insert", "update")) . ") /i", $this->sql))
return $pdostmt->rowCount();
}
} catch (PDOException $e) {
$this->error = $e->getMessage();
$this->debug();
return false;
}
}

Answer 1

DON'T TRY to automate everything
The less magic in your code, the easier support and less painful troubles.
Don't try to stuff all the logic into one single method. It's a class! You can create as many methods as you need.
When you need rowCount() - select it explicitly! It's not that hard.
But when you stumble upon this code after couple months, you will know what does this value mean.
When you need single row - use a method to get a single row.
When you need many rows - use a method to get many rows.
It is simple and extremely unambiguous!
When you turn back to your code after 2 months, you will have absolutely no idea, what did you expected. So - always write it explicitly.
Here is an excerpt from my mysqli wrapper class to give you an idea:
public function query()
{
return $this->rawQuery($this->prepareQuery(func_get_args()));
}
/**
* Helper function to get scalar value right out of query and optional arguments
*
* Examples:
* $name = $db->getOne("SELECT name FROM table WHERE id=1");
* $name = $db->getOne("SELECT name FROM table WHERE id=?i", $id);
*
* #param string $query - an SQL query with placeholders
* #param mixed $arg,... unlimited number of arguments to match placeholders in the query
* #return string|FALSE either first column of the first row of resultset or FALSE if none found
*/
public function getOne()
{
$query = $this->prepareQuery(func_get_args());
if ($res = $this->rawQuery($query))
{
$row = $this->fetch($res);
if (is_array($row)) {
return reset($row);
}
$this->free($res);
}
return FALSE;
}
/**
* Helper function to get single row right out of query and optional arguments
*
* Examples:
* $data = $db->getRow("SELECT * FROM table WHERE id=1");
* $data = $db->getOne("SELECT * FROM table WHERE id=?i", $id);
*
* #param string $query - an SQL query with placeholders
* #param mixed $arg,... unlimited number of arguments to match placeholders in the query
* #return array|FALSE either associative array contains first row of resultset or FALSE if none found
*/
public function getRow()
{
$query = $this->prepareQuery(func_get_args());
if ($res = $this->rawQuery($query)) {
$ret = $this->fetch($res);
$this->free($res);
return $ret;
}
return FALSE;
}
/**
* Helper function to get single column right out of query and optional arguments
*
* Examples:
* $ids = $db->getCol("SELECT id FROM table WHERE cat=1");
* $ids = $db->getCol("SELECT id FROM tags WHERE tagname = ?s", $tag);
*
* #param string $query - an SQL query with placeholders
* #param mixed $arg,... unlimited number of arguments to match placeholders in the query
* #return array|FALSE either enumerated array of first fields of all rows of resultset or FALSE if none found
*/
public function getCol()
{
$ret = array();
$query = $this->prepareQuery(func_get_args());
if ( $res = $this->rawQuery($query) )
{
while($row = $this->fetch($res))
{
$ret[] = reset($row);
}
$this->free($res);
}
return $ret;
}
/**
* Helper function to get all the rows of resultset right out of query and optional arguments
*
* Examples:
* $data = $db->getAll("SELECT * FROM table");
* $data = $db->getAll("SELECT * FROM table LIMIT ?i,?i", $start, $rows);
*
* #param string $query - an SQL query with placeholders
* #param mixed $arg,... unlimited number of arguments to match placeholders in the query
* #return array enumerated 2d array contains the resultset. Empty if no rows found.
*/
public function getAll()
{
$ret = array();
$query = $this->prepareQuery(func_get_args());
if ( $res = $this->rawQuery($query) )
{
while($row = $this->fetch($res))
{
$ret[] = $row;
}
$this->free($res);
}
return $ret;
}
Look - from the function name you can always tell which result to expect:
$name = $db->getOne('SELECT name FROM table WHERE id = ?i',$_GET['id']);
$data = $db->getAll("SELECT * FROM ?n WHERE mod=?s LIMIT ?i",$table,$mod,$limit);
Don't be fooled by such a pitfall like number of returned rows.
There could be honest one row in the resultset which you intend to populate with fetchAll. So, it will return single-dimensional array instead of multi-dimensional and you will have plenty of video effects on your page

Answer 2

Since you didn't mark an answer as accepted. I thought I'd answer you question. I found this while looking for the answer myself. I agree with "Your Common Sense" in that they should be two separate functions. However, in direct answer to your question, this is what I had (PDO example rather than mysqli):
function select($sql,$params=NULL,$fetchType=NULL){
try{
$qry = $this->db->prepare($sql);
$qry->execute($params);
if($qry->rowCount() > 1){
if($fetchType == 'OBJ'){//returns object
$results = $qry->fetchAll(PDO::FETCH_OBJ);
}elseif($fetchType == 'NUM'){//-numerical array
$results = $qry->fetchAll(PDO::FETCH_NUM);
}else{//default - associative array
$results = $qry->fetchAll(PDO::FETCH_ASSOC);
}
}
else{
if($fetchType == 'OBJ'){//returns object
$results = $qry->fetch(PDO::FETCH_OBJ);
}elseif($fetchType == 'NUM'){//-numerical array
$results = $qry->fetch(PDO::FETCH_NUM);
}else{//default - associative array
$results = $qry->fetch(PDO::FETCH_ASSOC);
}
}
if($results){
return $results;
}else{
return NULL;
}
}
catch(PDOException $err){
$this->logError($err);
}
}
However I found that if I queried all rows in a table but there was only one row in the table it would return a 1-d array instead of a 2-d array. My code to handle the result wouldn't work for both types of arrays. I could handle that each time but I found it just easier to, as stated above, separate them into different functions so if I knew there would be only one answer I could call the appropriate function. This is what I have now:
function select($sql,$params=NULL,$fetchType=NULL){
try{
$qry = $this->db->prepare($sql);
$qry->execute($params);
if($fetchType == 'OBJ'){//returns object
$results = $qry->fetch(PDO::FETCH_OBJ);
}elseif($fetchType == 'NUM'){//-numerical array
$results = $qry->fetch(PDO::FETCH_NUM);
}else{//default - associative array
$results = $qry->fetch(PDO::FETCH_ASSOC);
}
if($results){
return $results;
}else{
return NULL;
}
}
catch(PDOException $err){
$this->logError($err);
}
}
function selectAll($sql,$params=NULL,$fetchType=NULL){
try{
$qry = $this->db->prepare($sql);
$qry->execute($params);
if($fetchType == 'OBJ'){//returns object
$results = $qry->fetchAll(PDO::FETCH_OBJ);
}elseif($fetchType == 'NUM'){//-numerical array
$results = $qry->fetchAll(PDO::FETCH_NUM);
}else{//default - associative array
$results = $qry->fetchAll(PDO::FETCH_ASSOC);
}
if($results){
return $results;
}else{
return NULL;
}
}
catch(PDOException $err){
$this->logError($err);
}
}