Allow DQL functions to specify return type

lib/Doctrine/ORM/Query/AST/Functions/AbsFunction.php

@@ -24,7 +24,7 @@
 /**
  * "ABS" "(" SimpleArithmeticExpression ")"
  *
- * 
+ *
  * @link    www.doctrine-project.org
  * @since   2.0
  * @author  Guilherme Blanco <guilhermeblanco@hotmail.com>

lib/Doctrine/ORM/Query/AST/Functions/CountFunction.php

@@ -19,6 +19,8 @@
 
 namespace Doctrine\ORM\Query\AST\Functions;
 
+use Doctrine\DBAL\Types\Type;
+use Doctrine\ORM\Query\AST\TypedExpression;
 use Doctrine\ORM\Query\Parser;
 use Doctrine\ORM\Query\SqlWalker;
 use Doctrine\ORM\Query\AST\AggregateExpression;
@@ -29,7 +31,7 @@
  * @since   2.6
  * @author  Mathew Davies <thepixeldeveloper@icloud.com>
  */
-final class CountFunction extends FunctionNode
+final class CountFunction extends FunctionNode implements TypedExpression
 {
     /**
      * @var AggregateExpression
@@ -51,4 +53,9 @@ public function parse(Parser $parser): void
     {
         $this->aggregateExpression = $parser->AggregateExpression();
     }
+
+    public function getReturnType() : Type
+    {
+        return Type::getType(Type::INTEGER);
+    }
 }

lib/Doctrine/ORM/Query/AST/Functions/FunctionNode.php

@@ -24,7 +24,7 @@
 /**
  * Abstract Function Node.
  *
- * 
+ *
  * @link    www.doctrine-project.org
  * @since   2.0
  * @author  Guilherme Blanco <guilhermeblanco@hotmail.com>

lib/Doctrine/ORM/Query/AST/Functions/LengthFunction.php

@@ -19,6 +19,8 @@
 
 namespace Doctrine\ORM\Query\AST\Functions;
 
+use Doctrine\DBAL\Types\Type;
+use Doctrine\ORM\Query\AST\TypedExpression;
 use Doctrine\ORM\Query\Lexer;
 
 /**
@@ -32,7 +34,7 @@
  * @author  Roman Borschel <roman@code-factory.org>
  * @author  Benjamin Eberlei <kontakt@beberlei.de>
  */
-class LengthFunction extends FunctionNode
+class LengthFunction extends FunctionNode implements TypedExpression
 {
     public $stringPrimary;
 
@@ -60,4 +62,9 @@ public function parse(\Doctrine\ORM\Query\Parser $parser)
 
         $parser->match(Lexer::T_CLOSE_PARENTHESIS);
     }
+
+    public function getReturnType() : Type
+    {
+        return Type::getType(Type::INTEGER);
+    }
 }

lib/Doctrine/ORM/Query/AST/Functions/SqrtFunction.php

@@ -24,7 +24,7 @@
 /**
  * "SQRT" "(" SimpleArithmeticExpression ")"
  *
- * 
+ *
  * @link    www.doctrine-project.org
  * @since   2.0
  * @author  Guilherme Blanco <guilhermeblanco@hotmail.com>

lib/Doctrine/ORM/Query/AST/TypedExpression.php

@@ -0,0 +1,15 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\ORM\Query\AST;
+
+use Doctrine\DBAL\Types\Type;
+
+/**
+ * Provides an API for resolving the type of a Node
+ */
+interface TypedExpression
+{
+    public function getReturnType() : Type;
+}

lib/Doctrine/ORM/Query/SqlWalker.php

@@ -1339,10 +1339,20 @@ public function walkSelectExpression($selectExpression)
 
                 $this->scalarResultAliasMap[$resultAlias] = $columnAlias;
 
-                if ( ! $hidden) {
-                    // We cannot resolve field type here; assume 'string'.
+                if ($hidden) {
+                    break;
+                }
+
+                if (! $expr instanceof Query\AST\TypedExpression) {
+                    // Conceptually we could resolve field type here by traverse through AST to retrieve field type,
+                    // but this is not a feasible solution; assume 'string'.
                     $this->rsm->addScalarResult($columnAlias, $resultAlias, 'string');
+
+                    break;
                 }
+
+                $this->rsm->addScalarResult($columnAlias, $resultAlias, $expr->getReturnType()->getName());
+
                 break;
 
             case ($expr instanceof AST\Subselect):

tests/Doctrine/Tests/ORM/Functional/Ticket/GH7941Test.php

@@ -0,0 +1,101 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\Tests\ORM\Functional\Ticket;
+
+use DateTimeImmutable;
+use Doctrine\Tests\OrmFunctionalTestCase;
+use function ltrim;
+use function strlen;
+
+/** @group GH7941 */
+final class GH7941Test extends OrmFunctionalTestCase
+{
+    private const PRODUCTS = [
+        ['name' => 'Test 1', 'price' => '100', 'square_root' => '/^10(\.0+)?$/'],
+        ['name' => 'Test 2', 'price' => '100', 'square_root' => '/^10(\.0+)?$/'],
+        ['name' => 'Test 3', 'price' => '100', 'square_root' => '/^10(\.0+)?$/'],
+        ['name' => 'Test 4', 'price' => '25', 'square_root' => '/^5(\.0+)?$/'],
+        ['name' => 'Test 5', 'price' => '25', 'square_root' => '/^5(\.0+)?$/'],
+        ['name' => 'Test 6', 'price' => '-25', 'square_root' => '/^5(\.0+)?$/'],
+    ];
+
+    protected function setUp() : void
+    {
+        parent::setUp();
+
+        $this->setUpEntitySchema([GH7941Product::class]);
+
+        foreach (self::PRODUCTS as $product) {
+            $this->_em->persist(new GH7941Product($product['name'], $product['price']));
+        }
+
+        $this->_em->flush();
+        $this->_em->clear();
+    }
+
+    /** @test */
+    public function typesShouldBeConvertedForDQLFunctions() : void
+    {
+        $query = $this->_em->createQuery(
+            'SELECT
+                 COUNT(product.id) as count,
+                 SUM(product.price) as sales,
+                 AVG(product.price) as average
+             FROM ' . GH7941Product::class . ' product'
+        );
+
+        $result = $query->getSingleResult();
+
+        self::assertSame(6, $result['count']);
+        self::assertSame('325', $result['sales']);
+        self::assertRegExp('/^54\.16+7$/', $result['average']);
+
+        $query = $this->_em->createQuery(
+            'SELECT
+                 ABS(product.price) as absolute,
+                 SQRT(ABS(product.price)) as square_root,
+                 LENGTH(product.name) as length
+             FROM ' . GH7941Product::class . ' product'
+        );
+
+        foreach ($query->getResult() as $i => $item) {
+            $product = self::PRODUCTS[$i];
+
+            self::assertSame(ltrim($product['price'], '-'), $item['absolute']);
+            self::assertSame(strlen($product['name']), $item['length']);
+            self::assertRegExp($product['square_root'], $item['square_root']);
+        }
+    }
+}
+
+/**
+ * @Entity
+ * @Table()
+ */
+class GH7941Product
+{
+    /**
+     * @Id
+     * @GeneratedValue
+     * @Column(type="integer")
+     */
+    public $id;
+
+    /** @Column(type="string") */
+    public $name;
+
+    /** @Column(type="decimal") */
+    public $price;
+
+    /** @Column(type="datetime_immutable") */
+    public $createdAt;
+
+    public function __construct(string $name, string $price)
+    {
+        $this->name      = $name;
+        $this->price     = $price;
+        $this->createdAt = new DateTimeImmutable();
+    }
+}