added selective field translation to the translateable extension

src/Translatable/Query/TreeWalker/TranslationWalker.php

@@ -79,6 +79,13 @@ class TranslationWalker extends SqlWalker
      */
     public const HYDRATE_SIMPLE_OBJECT_TRANSLATION = '__gedmo.translatable.simple_object.hydrator';
 
+    /**
+     * Name for "only fields" hint
+     *
+     * @internal
+     */
+    const HINT_ONLY_FIELDS = '__gedmo.translatable.only_fields';
+
     /**
      * Stores all component references from select clause
      *
@@ -272,6 +279,7 @@ private function prepareTranslatedComponents(): void
         $ea->setEntityManager($em);
         $quoteStrategy = $em->getConfiguration()->getQuoteStrategy();
         $joinStrategy = $q->getHint(TranslatableListener::HINT_INNER_JOIN) ? 'INNER' : 'LEFT';
+        $onlyFields = $q->getHint(self::HINT_ONLY_FIELDS);
 
         foreach ($this->translatedComponents as $dqlAlias => $comp) {
             /** @var ClassMetadata $meta */
@@ -281,6 +289,13 @@ private function prepareTranslatedComponents(): void
             $transMeta = $em->getClassMetadata($transClass);
             $transTable = $quoteStrategy->getTableName($transMeta, $this->platform);
             foreach ($config['fields'] as $field) {
+                if ($onlyFields) {
+                    $checkField = $dqlAlias.'.'.$field;
+                    if (!\in_array($checkField, $onlyFields, true)) {
+                        continue;
+                    }
+                }
+
                 $compTblAlias = $this->walkIdentificationVariable($dqlAlias, $field);
                 $tblAlias = $this->getSQLTableAlias('trans'.$compTblAlias.$field);
                 $sql = " {$joinStrategy} JOIN ".$transTable.' '.$tblAlias;