diff --git a/DependencyInjection/ChillMainExtension.php b/DependencyInjection/ChillMainExtension.php
index feafc9f04..0399cc512 100644
--- a/DependencyInjection/ChillMainExtension.php
+++ b/DependencyInjection/ChillMainExtension.php
@@ -26,6 +26,9 @@ use Symfony\Component\DependencyInjection\Loader;
 use Symfony\Component\DependencyInjection\Extension\PrependExtensionInterface;
 use Chill\MainBundle\DependencyInjection\Widget\Factory\WidgetFactoryInterface;
 use Chill\MainBundle\DependencyInjection\Configuration;
+use Chill\MainBundle\Doctrine\DQL\GetJsonFieldByKey;
+use Chill\MainBundle\Doctrine\DQL\Unaccent;
+use Chill\MainBundle\Doctrine\DQL\JsonAggregate;
 
 /**
  * This class load config for chillMainExtension.
@@ -128,7 +131,9 @@ class ChillMainExtension extends Extension implements PrependExtensionInterface,
            'orm' => array(
               'dql' => array(
                  'string_functions' => array(
-                    'unaccent' => 'Chill\MainBundle\Doctrine\DQL\Unaccent'
+                    'unaccent' => Unaccent::class,
+                    'GET_JSON_FIELD_BY_KEY' => GetJsonFieldByKey::class,
+                    'AGGREGATE' => JsonAggregate::class
                  )
               )
            )
diff --git a/Doctrine/DQL/GetJsonFieldByKey.php b/Doctrine/DQL/GetJsonFieldByKey.php
new file mode 100644
index 000000000..addc6b9b7
--- /dev/null
+++ b/Doctrine/DQL/GetJsonFieldByKey.php
@@ -0,0 +1,53 @@
+<?php
+/*
+ * Copyright (C) 2017 Champs Libres Cooperative <info@champs-libres.coop>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+namespace Chill\MainBundle\Doctrine\DQL;
+
+use Doctrine\ORM\Query\AST\Functions\FunctionNode;
+use Doctrine\ORM\Query\Lexer;
+use Doctrine\ORM\Query\Parser;
+use Doctrine\ORM\Query\SqlWalker;
+
+/**
+ * 
+ *
+ * @author Julien Fastré <julien.fastre@champs-libres.coop>
+ */
+class GetJsonFieldByKey extends FunctionNode
+{
+    private $expr1;
+    private $expr2;
+
+    public function parse(Parser $parser)
+    {
+        $parser->match(Lexer::T_IDENTIFIER);
+        $parser->match(Lexer::T_OPEN_PARENTHESIS);
+        $this->expr1 = $parser->StringPrimary();
+        $parser->match(Lexer::T_COMMA);
+        $this->expr2 = $parser->StringPrimary();
+        $parser->match(Lexer::T_CLOSE_PARENTHESIS);
+    }
+
+    public function getSql(SqlWalker $sqlWalker)
+    {
+        return sprintf(
+            '(%s->%s)',
+            $this->expr1->dispatch($sqlWalker),
+            $this->expr2->dispatch($sqlWalker)
+        );
+    }
+}
diff --git a/Doctrine/DQL/JsonAggregate.php b/Doctrine/DQL/JsonAggregate.php
new file mode 100644
index 000000000..54ef45493
--- /dev/null
+++ b/Doctrine/DQL/JsonAggregate.php
@@ -0,0 +1,49 @@
+<?php
+/*
+ * Copyright (C) 2017 Champs Libres Cooperative <info@champs-libres.coop>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+namespace Chill\MainBundle\Doctrine\DQL;
+
+use Doctrine\ORM\Query\AST\Functions\FunctionNode;
+use Doctrine\ORM\Query\Lexer;
+use Doctrine\ORM\Query\Parser;
+use Doctrine\ORM\Query\SqlWalker;
+
+/**
+ * Return an aggregation of values in a json representation, as a string.
+ * 
+ * Internally, this function use the postgresql `jsonb_agg` function. Using
+ * json allow to aggregate data from different types without have to cast them.
+ *
+ * @author Julien Fastré <julien.fastre@champs-libres.coop>
+ */
+class JsonAggregate extends FunctionNode
+{
+    private $expr;
+    
+    public function getSql(SqlWalker $sqlWalker)
+    {
+        return sprintf('jsonb_agg(%s)', $this->expr->dispatch($sqlWalker));
+    }
+
+    public function parse(Parser $parser)
+    {
+        $parser->match(Lexer::T_IDENTIFIER);
+        $parser->match(Lexer::T_OPEN_PARENTHESIS);
+        $this->expr = $parser->StringPrimary();
+        $parser->match(Lexer::T_CLOSE_PARENTHESIS);
+    }
+}