Question

I am trying to place a variable into the field name in the query , so I have a schema:

  id amazon - tesco - asda - happyshopper - 

  1   £5    - NULL  - NULL  -     £4.99
  2   NULL  - £2.99 - NULL  -     NULL

and then

$store = 'amazon'; 

$qb = $em->createQueryBuilder();
        $products = $qb->select('p')->from('MyBundle:Product', 'p')
        ->where('p.:store IS NOT NULL')
        ->setParameter('store', $store)
        ->add('orderBy', 'p.onSale DESC')
        ->setMaxResults(40)
        ->getQuery()
        ->getResult();

Would return row 1.

What I’ve done for :

->where('p.:store IS NOT NULL')
->setParameter('store', $store)

Is incorrect and it errors.

->where(':store IS NOT NULL')
->setParameter('store', $store)

does not error, but doesn’t apply the store filter.

Answer 1

The short answer here is to just work the store name into the string manually:

->where("p.$store IS NOT NULL")

or

->where('p.' . $store . ' IS NOT NULL')

The long answer is that your database schema could use some work. What happens, for example, if/when you want to add a new store? Are you going to add a new column and re-code the whole thing? The better solution is to separate the concept of “store”, put it in its own table, and join everything together in a different table. Something like this:

Product:
id | name | onSale
1  | foo  | 1
2  | bar  | 0

Store:
id | name    
1  | amazon
2  | tesco
3  | asda
4  | happyshopper

Price:
id | productId | storeId | price
1  | 1         | 1       | 5
2  | 1         | 4       | 4.99
3  | 2         | 2       | 2.99

Once you configure your tables and your mappings properly, your query turns in to:

$qb = $em->createQueryBuilder();
$products = $qb
    ->select('product')
    ->from('MyBundle:Price', 'price')
    ->innerJoin('price.product', 'product')
    ->innerJoin('price.store', 'store')
    ->where('store.name = :store')
    ->setParameter('store', $store)
    ->add('orderBy', 'product.onSale DESC')
    ->setMaxResults(40)
    ->getQuery()
    ->getResult();