Symfony：表为空时，$ query-> getResult（）不返回任何内容

Question

I want to show in a list all the data stored in a specific table in my database.

After doing my query, I want to get the number of results to display them or not.

public function listUseCaseAction(Request $request) {    
    // Load use cases from database
    $em   = $this->getDoctrine()->getManager();
    $repo = $em->getRepository('AppBundle:TagUseCase');

    $query = $repo->createQueryBuilder('case')
        ->select(array('case.code', 'case.name'))
        ->orderBy('case.name', 'ASC')
        ->getQuery();

    if (count($query->getResult()) > 0) {
        // display list
    } else {
        // message : "There is no use case."        
    }
}

The problem is that $query->getResult() seems to not return anything when a table is empty. Neither false nor null...

It returns a number only when there is data.

DQL :

'SELECT case.code, case.name FROM AppBundle\Entity\TagUseCase case ORDER BY case.name ASC'

Note : I have to get a query because I use KnpPaginator. I tried $repository->findAll() and it works even a table is empty (returns an empty array) but sortable columns doesn't work anymore. It works only with a query.

I also tried this but it doesn't work neither, it returns nothing when there is 0 result :

$qb = $em->createQueryBuilder();
$qb->select($qb->expr()->count('case.code'));
$qb->from('AppBundle:TagUseCase','case');

$count = $qb->getQuery()->getSingleScalarResult();

My question is : How can I count results of a query (even if there is no result) ?

Answer 1

If you use the query to iterate thought the list, it is better to use php count than an additional query.

Result as object, count with php:

$qb = $repo->createQueryBuilder('case')
        ->orderBy('case.name', 'ASC')
        ;
$result = $qb->getQuery()->getResult();
var_dump(count($result));

Answer 2

I found the problem !

You should never use the string " case " in a query, it is a SQL reserved word !!

Instead of :

$query = $repo->createQueryBuilder('case')
    ->select(array('case.code', 'case.name'))
    ->orderBy('case.name', 'ASC')
    ->getQuery();

Write :

$query = $repo->createQueryBuilder('c')
    ->select(array('c.code', 'c.name'))
    ->orderBy('c.name', 'ASC')
    ->getQuery();

The error [Syntax Error] line 0, col 17: Error: Expected Doctrine\\ORM\\Query\\Lexer::T_WHEN, got 'AppBundle\\Entity\\TagUseCase' is definitively no useful at all...

Answer 3

I suggest using Query::count() method:

if ($query->count()) > 0) {
    // display list
} ...