Converting MySQL to Doctrine Query Builder. Issues with IF and CONCAT. Or another approach for subqueries on select

Question

I have a table for my categories, each category have and id, name and parent_id.

Select IF(a.parent_id IS NULL, a.name, CONCAT((SELECT b.name FROM category b WHERE b.id = a.parent_id), " / ", a.name) ) as n, a.id, a.parent_id
FROM category a
ORDER BY n

I want to convert it to my Doctrine2 Query Builder

    $em = $this->getDoctrine()->getEntityManager();
    $qb = $em->createQueryBuilder();
    $q = $qb
            ->select("c.id")
            ->addSelect(
                "IF(c.parent_id IS NULL, c.name, CONCAT((" .
                $em->createQueryBuilder()
                   ->select("t.name")
                   ->from("MyBundle:Category", "t")
                   ->getQuery()->getDQL() .
                "), \" / \", c.name) )"
            )
            ->from("MyBundle:Category", "c");
    echo $q->getQuery()->getSQL();
    exit;

Something like that, but I cant use the IF, and CONCAT.

score 58 · Accepted Answer · edited Apr 30 '15 at 19:10

Ok I found the solution.

You can use CASE instead of IF. Check this out, but when I am using CASE I can't CONCAT my fields:

$em = $this->getDoctrine()->getEntityManager();
$qb = $em->createQueryBuilder();
$q = $qb
      ->select("c.id")
      ->addSelect("CASE WHEN (c.parent IS NULL) THEN c.name ELSE 'something' END")
      ->from("MyBundle:Category", "c")
      ->leftJoin("c.parent", "t");

echo $q->getQuery()->getSQL();

Another Solution is create your own DQL function, like IF and use it like this:

$em = $this->getDoctrine()->getEntityManager();
$qb = $em->createQueryBuilder();
$q = $qb
      ->select("c.id")
      ->addSelect("IF(c.parent IS NULL, c.name, CONCAT(CONCAT(t.name, ' / '), c.name))")
      ->from("MyBundle:Category", "c")
      ->leftJoin("c.parent", "t");

echo $q->getQuery()->getSQL();

For create this IF you can go to this link and learn: http://docs.doctrine-project.org/projects/doctrine-orm/en/latest/reference/dql-doctrine-query-language.html#adding-your-own-functions-to-the-dql-language

I will post here my class for this IF and the config.yml to help other people. Here is the IfFunction class (I got that from https://github.com/beberlei/DoctrineExtensions/blob/master/src/Query/Mysql/IfElse.php):

<?php
namespace MyName\MiscBundle\Doctrine\ORM\Query\AST\Functions;

use Doctrine\ORM\Query\AST\Functions\FunctionNode;
use Doctrine\ORM\Query\Lexer;

/**
 * Usage: IF(expr1, expr2, expr3)
 * 
 * If expr1 is TRUE (expr1 <> 0 and expr1 <> NULL) then IF() returns expr2;
 * otherwise it returns expr3. IF() returns a numeric or string value,
 * depending on the context in which it is used. 
 * 
 * @author  Andrew Mackrodt <andrew@ajmm.org>
 * @version 2011.06.19
 */
class IfFunction extends FunctionNode
{
    private $expr = array();

    public function parse(\Doctrine\ORM\Query\Parser $parser)
    {
        $parser->match(Lexer::T_IDENTIFIER);
        $parser->match(Lexer::T_OPEN_PARENTHESIS);
        $this->expr[] = $parser->ConditionalExpression();

        for ($i = 0; $i < 2; $i++)
        {
            $parser->match(Lexer::T_COMMA);
            $this->expr[] = $parser->ArithmeticExpression();
        }

        $parser->match(Lexer::T_CLOSE_PARENTHESIS);
    }

    public function getSql(\Doctrine\ORM\Query\SqlWalker $sqlWalker)
    {
        return sprintf('IF(%s, %s, %s)',
            $sqlWalker->walkConditionalExpression($this->expr[0]),
            $sqlWalker->walkArithmeticPrimary($this->expr[1]),
            $sqlWalker->walkArithmeticPrimary($this->expr[2]));
    }
}

After that you need to update your config.yml like this (just added the last 3 lines):

doctrine:
    dbal:
        driver:   "%database_driver%"
        host:     "%database_host%"
        port:     "%database_port%"
        dbname:   "%database_name%"
        user:     "%database_user%"
        password: "%database_password%"
        charset:  UTF8

    orm:
        auto_generate_proxy_classes: "%kernel.debug%"
        auto_mapping: true
        dql: #ADDED THIS LINE
            string_functions: #ADDED THIS LINE
                IF: MyName\MiscBundle\Doctrine\ORM\Query\AST\Functions\IfFunction #ADDED THIS LINE

Thanks

with the most recent version of symfony - the dql node has to be below the entity_manager — Harold, Jan 23 '14 at 17:19

score 2 · Answer 2 · edited Aug 03 '15 at 13:18

2

You can also combine CASE and CONCAT:

$q = $this->createQueryBuilder('a')
    ->select('a.id')
    ->addSelect('CASE WHEN(a.parent IS NULL) THEN \'\' else CONCAT(:variable, a.name, \'string\') END as name')
    ->setParameter('variable', $variable)
    ... ;

edited Aug 03 '15 at 13:18

dakab

5,379
9
43
67

answered Aug 03 '15 at 12:42

justb3a

21
2

score 0 · Answer 3 · answered Dec 31 '12 at 09:53

0

Assuming you have a relation named "parent" in Category, does this work better? :

$em = $this->getDoctrine()->getEntityManager();
$qb = $em->createQueryBuilder();
$q  = $qb
      ->select("c.id")
   ->addSelect("IF (c.parent_id IS NULL, c.name, CONCAT(t.name, ' / ', c.name))"
        ->from("MyBundle:Category", "c")
    ->leftJoin("c.parent t"));

echo $q->getQuery()->getSQL();

answered Dec 31 '12 at 09:53

greg0ire

22,714
16
72
101

Thanks for the tip, this way will works too. But i dont know I cant use the `IF` on the `addSelect`. I get this error: `[Syntax Error] line 0, col 13: Error: Expected known function, got 'IF'` – Thiago Festa Jan 01 '13 at 00:04
Yes please... I got the same problem using this: "->select(array('SUM(IF(aliasImUsing.fieldCouldBe1Or0 = 1, 1, 0) = 1) AS num_OfOnes'))". The error message is the same one: "[Syntax Error] line 0, col 11: Error: Expected known function, got 'IF'" – Ricard Espinàs Llovet May 31 '18 at 15:49

Converting MySQL to Doctrine Query Builder. Issues with IF and CONCAT. Or another approach for subqueries on select

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