diff --git a/lib/Alchemy/Phrasea/SearchEngine/Elastic/Structure/Field.php b/lib/Alchemy/Phrasea/SearchEngine/Elastic/Structure/Field.php
index d7b32b0108..1922959501 100644
--- a/lib/Alchemy/Phrasea/SearchEngine/Elastic/Structure/Field.php
+++ b/lib/Alchemy/Phrasea/SearchEngine/Elastic/Structure/Field.php
@@ -20,6 +20,7 @@ class Field
     private $is_private;
     private $is_facet;
     private $thesaurus_roots;
+    private $used_by_collections;
 
     public static function createFromLegacyField(databox_field $field)
     {
@@ -54,9 +55,9 @@ class Field
             case databox_field::TYPE_STRING:
             case databox_field::TYPE_TEXT:
                 return Mapping::TYPE_STRING;
-            default:
-                throw new Exception(sprintf('Invalid field type "%s", expected "date", "number" or "string".', $type));
         }
+
+        throw new \InvalidArgumentException(sprintf('Invalid field type "%s", expected "date", "number" or "string".', $type));
     }
 
     public function __construct($name, $type, array $options = [])
@@ -97,6 +98,11 @@ class Field
         return $this->type;
     }
 
+    public function getCollections()
+    {
+        return $this->collections;
+    }
+
     public function isSearchable()
     {
         return $this->is_searchable;
diff --git a/lib/classes/databox.php b/lib/classes/databox.php
index fa6d8d5c0a..6a5d049e95 100644
--- a/lib/classes/databox.php
+++ b/lib/classes/databox.php
@@ -208,6 +208,9 @@ class databox extends base
         return $this->ord;
     }
 
+    /**
+     * @return appbox
+     */
     public function get_appbox()
     {
         return $this->app['phraseanet.appbox'];
@@ -235,10 +238,8 @@ class databox extends base
             return $base_ids;
         }
 
-        $conn = $this->app['phraseanet.appbox']->get_connection();
-        $sql = "SELECT b.base_id FROM bas b
-            WHERE b.sbas_id = :sbas_id AND b.active = '1'
-            ORDER BY b.ord ASC";
+        $conn = $this->get_appbox()->get_connection();
+        $sql = "SELECT b.base_id FROM bas b WHERE b.sbas_id = :sbas_id AND b.active = '1' ORDER BY b.ord ASC";
         $stmt = $conn->prepare($sql);
         $stmt->execute([':sbas_id' => $this->id]);
         $rs = $stmt->fetchAll(PDO::FETCH_ASSOC);
diff --git a/tests/Alchemy/Tests/Phrasea/SearchEngine/Structure/FieldTest.php b/tests/Alchemy/Tests/Phrasea/SearchEngine/Structure/FieldTest.php
index 2e8575c0d3..3a5e49dd77 100644
--- a/tests/Alchemy/Tests/Phrasea/SearchEngine/Structure/FieldTest.php
+++ b/tests/Alchemy/Tests/Phrasea/SearchEngine/Structure/FieldTest.php
@@ -14,8 +14,8 @@ class FieldTest extends \PHPUnit_Framework_TestCase
 {
     public function testBasicMerge()
     {
-        $field = new Field('foo', Mapping::TYPE_STRING);
-        $other = new Field('foo', Mapping::TYPE_STRING);
+        $field = new Field('foo', Mapping::TYPE_STRING, ['used_by_collections' => ['1', '2']]);
+        $other = new Field('foo', Mapping::TYPE_STRING, ['used_by_collections' => ['3', '4']]);
         $merged = $field->mergeWith($other);
         $this->assertInstanceOf(Field::class, $merged);
         $this->assertNotSame($field, $merged);
@@ -26,6 +26,7 @@ class FieldTest extends \PHPUnit_Framework_TestCase
         $this->assertFalse($merged->isPrivate());
         $this->assertFalse($merged->isFacet());
         $this->assertNull($merged->getThesaurusRoots());
+        $this->assertEquals(['1', '2', '3', '4'], $merged->getCollections());
     }
 
     /**
diff --git a/tests/Alchemy/Tests/Phrasea/SearchEngine/Structure/StructureTest.php b/tests/Alchemy/Tests/Phrasea/SearchEngine/Structure/StructureTest.php
index 46b79929d7..93bd0fb042 100644
--- a/tests/Alchemy/Tests/Phrasea/SearchEngine/Structure/StructureTest.php
+++ b/tests/Alchemy/Tests/Phrasea/SearchEngine/Structure/StructureTest.php
@@ -34,22 +34,21 @@ class StructureTest extends \PHPUnit_Framework_TestCase
         $field->isPrivate()->willReturn(false);
         $field->isFacet()->willReturn(false);
         $field->hasConceptInference()->willReturn(false);
+        $field->getCollections()->willReturn(['1']);
 
         $structure->add($field->reveal());
         $this->assertCount(1, $structure->getAllFields());
 
-        $conflicting_field = $this->prophesize(Field::class);
-        $conflicting_field->getName()->willReturn('foo');
-        $conflicting_field->getType()->willReturn(Mapping::TYPE_STRING);
-        $conflicting_field->isPrivate()->willReturn(false);
-        $conflicting_field->isFacet()->willReturn(false);
-        $conflicting_field->hasConceptInference()->willReturn(false);
-        $dummy = $conflicting_field->reveal();
+        $conflicting_field = new Field('foo', Mapping::TYPE_STRING, ['2']);
 
-        $field->mergeWith($dummy)->willReturn($dummy);
+        $merged = new Field('foo', Mapping::TYPE_STRING, ['1', '2']);
+
+        $field->mergeWith($conflicting_field)->willReturn($merged);
         // Should still have only one (both have the same name)
-        $structure->add($dummy);
-        $this->assertCount(1, $structure->getAllFields());
+        $structure->add($conflicting_field);
+        $this->assertCount(1, $fields = $structure->getAllFields());
+        $this->assertInternalType('array', $fields);
+        $this->assertSame($merged, reset($fields));
     }
 
     public function testFieldMerge()
@@ -166,7 +165,7 @@ class StructureTest extends \PHPUnit_Framework_TestCase
     }
 
     /**
-     * @expectedException DomainException
+     * @expectedException \DomainException
      * @expectedExceptionMessageRegExp #field#u
      */
     public function testPrivateCheckWithInvalidField()