Doctrine createQueryBuilder multiple conditional where statements a bit clunky - php

Question

I have an itemid and a category id that are both conditional. If none is given then all items are shown newest fist. If itemid is given then only items with an id lower than given id are shown (for paging). If category id is given than only items in a certain category are shown and if both are given than only items from a certain category where item id smaller than itemid are shown (items by category next page).
Because the parameters are conditional you get a lot of if statements depending on the params when building a SQL string (pseudo code I'm wearing out my dollar sign with php stuff):
if itemid ' where i.iid < :itemid '
if catid
if itemid
' and c.id = :catid'
else
' where c.id = :catid'
end if
end if
If more optional parameters are given this will turn very messy so I thought I'd give the createQueryBuilder a try. Was hoping for something like this:
if($itemId!==false){
$qb->where("i.id < :id");
}
if($categoryId!==false){
$qb->where("c.id = :catID");
}
This is sadly not so and the last where will overwrite the first one
What I came up with is this (in Symfony2):
private function getItems($itemId,$categoryId){
$qb=$this->getDoctrine()->getRepository('mrBundle:Item')
->createQueryBuilder('i');
$arr=array();
$qb->innerJoin('i.categories', 'c', null, null);
$itemIdWhere=null;
$categoryIdWhere=null;
if($itemId!==false){
$itemIdWhere=("i.id < :id");
}
if($categoryId!==false){
$categoryIdWhere=("c.id = :catID");
}
if($itemId!==false||$categoryId!==false){
$qb->where($itemIdWhere,$categoryIdWhere);
}
if($itemId!==false){
$qb->setParameter(':id', $itemId);
}
if($categoryId!==false){
$arr[]=("c.id = :catID");
$qb->setParameter(':catID', $categoryId);
}
$qb->add("orderBy", "i.id DESC")
->setFirstResult( 0 )
->setMaxResults( 31 );
I'm not fully trusting the $qb->where(null,null) although it is currently not creating errors or unexpected results. It looks like these parameters are ignored. Could not find anything in the documentation but an empty string would generate an error $qb->where('','').
It also looks a bit clunky to me still, if I could use multiple $qb->where(condition) then only one if statement per optional would be needed $qb->where(condition)->setParameter(':name', $val);
So the question is: Is there a better way?
I guess if doctrine had a function to escape strings I can get rid of the second if statement round (not sure if malicious user could POST something in a different character set that would allow sql injection):
private function getItems($itemId,$categoryId){
$qb=$this->getDoctrine()->getRepository('mrBundle:Item')
->createQueryBuilder('i');
$arr=array();
$qb->innerJoin('i.categories', 'c', null, null);
$itemIdWhere=null;
$categoryIdWhere=null;
if($itemId!==false){
$itemIdWhere=("i.id < ".
someDoctrineEscapeFunction($id));
}
Thank you for reading this far and hope you can enlighten me.
[UPDATE]
I am currently using a dummy where statement so any additional conditional statements can be added with andWhere:
$qb->where('1=1');// adding a dummy where
if($itemId!==false){
$qb->andWhere("i.id < :id")
->setParameter(':id',$itemId);
}
if($categoryId!==false){
$qb->andWhere("c.id = :catID")
->setParameter(':catID',$categoryId);
}

Answer 1

You can create filters if you want to use more generic approach of handling this.
Doctrine 2.2 features a filter system that allows the developer to add SQL to the conditional clauses of queries
Read more about filters however, I'm handling this in similar manner as you showed