diff --git a/src/Controller/Controller.php b/src/Controller/Controller.php
index 29f584c..9f9bf83 100644
--- a/src/Controller/Controller.php
+++ b/src/Controller/Controller.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -220,8 +220,7 @@ function ($d) {
 
             if ($parsed !== null) {
                 //overwrite
-                if (
-                    $overwrite
+                if ($overwrite
                     && (
                     $key = array_search(
                         $directiveClass,
diff --git a/src/Controller/Delete.php b/src/Controller/Delete.php
index 9f98a05..1b9a65b 100644
--- a/src/Controller/Delete.php
+++ b/src/Controller/Delete.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -41,7 +41,7 @@ public static function handleDelete(
         array $validationCallbacks = [],
         callable $viewCallback = null,
         int $bulkLimit = null,
-        array $directives
+        array $directives = []
     ) : ResponseInterface {
         //Validate id using model's validator
         $id = $model->getIdAttributeValidator()->parse($id);
@@ -63,4 +63,4 @@ public static function handleDelete(
 
         //204 or view callback
     }
-}
\ No newline at end of file
+}
diff --git a/src/Controller/Get.php b/src/Controller/Get.php
index 5cfd3e6..5e5104b 100644
--- a/src/Controller/Get.php
+++ b/src/Controller/Get.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -48,8 +48,7 @@ public static function handleGet(
         ResponseInterface $response,
         ResourceModel $model,
         array $directives = []
-    ) : ResponseInterface
-    {
+    ) : ResponseInterface {
         //Parse request related directives from request
         $directives = Controller::parseDirectives(
             [
@@ -96,4 +95,4 @@ public static function handleGet(
             )
         );
     }
-}
\ No newline at end of file
+}
diff --git a/src/Controller/GetById.php b/src/Controller/GetById.php
index 0ee1a6c..1bbc9bf 100644
--- a/src/Controller/GetById.php
+++ b/src/Controller/GetById.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -91,4 +91,4 @@ public static function handleGetById(
             )
         );
     }
-}
\ No newline at end of file
+}
diff --git a/src/Controller/Helper/RequestBodyQueue.php b/src/Controller/Helper/RequestBodyQueue.php
index 3f2ebb4..f2a2dfa 100644
--- a/src/Controller/Helper/RequestBodyQueue.php
+++ b/src/Controller/Helper/RequestBodyQueue.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -55,4 +55,4 @@ public static function handleResource(
 
         return new ResourceQueueItem($attributes, $relationships);
     }
-}
\ No newline at end of file
+}
diff --git a/src/Controller/Helper/ResourceQueueItem.php b/src/Controller/Helper/ResourceQueueItem.php
index 0b3ec36..09e35b6 100644
--- a/src/Controller/Helper/ResourceQueueItem.php
+++ b/src/Controller/Helper/ResourceQueueItem.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -62,6 +62,4 @@ public function getRelationships() : \stdClass
     {
         return $this->relationships;
     }
-
-
 }
diff --git a/src/Controller/Patch.php b/src/Controller/Patch.php
index 97284a3..950403d 100644
--- a/src/Controller/Patch.php
+++ b/src/Controller/Patch.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -42,7 +42,7 @@ public static function handlePatch(
         array $validationCallbacks = [],
         callable $viewCallback = null,
         int $bulkLimit = null,
-        array $directives
+        array $directives = []
     ) : ResponseInterface {
         //Validate id using model's validator
         $id = $model->getIdAttributeValidator()->parse($id);
@@ -64,4 +64,4 @@ public static function handlePatch(
 
         //204 or view callback
     }
-}
\ No newline at end of file
+}
diff --git a/src/Controller/Post.php b/src/Controller/Post.php
index 0fd8ee0..185ca8f 100644
--- a/src/Controller/Post.php
+++ b/src/Controller/Post.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -62,8 +62,7 @@ public static function handlePost(
         $isBulk = true;
 
         //Treat all request data (bulk or not) as an array of resources
-        if (
-            is_object($data)
+        if (is_object($data)
             || (is_array($data) && Util::isArrayAssoc($data))
         ) {
             $isBulk = false;
@@ -195,15 +194,15 @@ public static function handlePost(
             );
         }
 
-        if (count($ids) === 1) {
+        /*if (count($ids) === 1) {
             //Prepare response with 201 Created status code
             return Response::created(
                 $response,
                 'link' . $ids[0] // location
             );
-        }
+        }*/ //see https://stackoverflow.com/questions/11309444/can-the-location-header-be-used-for-multiple-resource-locations-in-a-201-created
 
         //Return 204 No Content
         return Response::noContent($response);
     }
-}
\ No newline at end of file
+}
diff --git a/src/Controller/Put.php b/src/Controller/Put.php
index 0db4154..65ba1cd 100644
--- a/src/Controller/Put.php
+++ b/src/Controller/Put.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -41,7 +41,7 @@ public static function handlePut(
         array $validationCallbacks = [],
         callable $viewCallback = null,
         int $bulkLimit = null,
-        array $directives
+        array $directives = []
     ) : ResponseInterface {
         //Validate id using model's validator
         $id = $model->getIdAttributeValidator()->parse($id);
@@ -63,4 +63,4 @@ public static function handlePut(
 
         //204 or view callback
     }
-}
\ No newline at end of file
+}
diff --git a/src/Controller/Relationship.php b/src/Controller/Relationship.php
index 22870cf..74d6b09 100644
--- a/src/Controller/Relationship.php
+++ b/src/Controller/Relationship.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -24,4 +24,4 @@
  */
 trait Relationship
 {
-}
\ No newline at end of file
+}
diff --git a/src/Controller/Response.php b/src/Controller/Response.php
index ab24455..85876d6 100644
--- a/src/Controller/Response.php
+++ b/src/Controller/Response.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/src/DataSource/DataSource.php b/src/DataSource/DataSource.php
index e1f9968..27dd829 100644
--- a/src/DataSource/DataSource.php
+++ b/src/DataSource/DataSource.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/src/DataSource/DatabaseDataSource.php b/src/DataSource/DatabaseDataSource.php
index f5d4578..f5c9e9b 100644
--- a/src/DataSource/DatabaseDataSource.php
+++ b/src/DataSource/DatabaseDataSource.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -145,7 +145,7 @@ public function requireTableSetting() : string
     public function handleGet(
         string $query,
         bool $queryHasWhere = false,
-        array $directives
+        array $directives = []
     ) {
         $model = $this->resourceModel;
 
@@ -223,10 +223,10 @@ private function handleSort(
             );*/
 
             $replace = "\n" . sprintf(
-                    'ORDER BY "%s" %s',
-                    $sortAttribute,
-                    ($sort->getAttribute() ? 'ASC' : 'DESC')
-                );
+                'ORDER BY "%s" %s',
+                $sortAttribute,
+                ($sort->getAttribute() ? 'ASC' : 'DESC')
+            );
         }
 
         $query = str_replace(
@@ -289,9 +289,9 @@ private function handleFilterParseIn(array $array)
         return implode(
             ',',
             array_map(
-            /**
-             * Apply single quotes around key
-             */
+                /**
+                 * Apply single quotes around key
+                 */
                 function ($key) {
                     return '\'' . $key . '\'';
                 },
diff --git a/src/Directive/AdditionalParameters.php b/src/Directive/AdditionalParameters.php
index 421838a..2b9b0de 100644
--- a/src/Directive/AdditionalParameters.php
+++ b/src/Directive/AdditionalParameters.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/src/Directive/AdditionalRelationshipParameters.php b/src/Directive/AdditionalRelationshipParameters.php
index 63ca344..92808fb 100644
--- a/src/Directive/AdditionalRelationshipParameters.php
+++ b/src/Directive/AdditionalRelationshipParameters.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/src/Directive/Directive.php b/src/Directive/Directive.php
index 8331b6f..579615d 100644
--- a/src/Directive/Directive.php
+++ b/src/Directive/Directive.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -106,8 +106,7 @@ function ($d) {
 
             if ($parsed !== null) {
                 //overwrite
-                if (
-                    $overwrite
+                if ($overwrite
                     && (
                     $key = array_search(
                         $directiveClass,
diff --git a/src/Directive/Fields.php b/src/Directive/Fields.php
index e1a0559..373a7df 100644
--- a/src/Directive/Fields.php
+++ b/src/Directive/Fields.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/src/Directive/Filter.php b/src/Directive/Filter.php
index f78fa04..8ea821d 100644
--- a/src/Directive/Filter.php
+++ b/src/Directive/Filter.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -274,7 +274,8 @@ public function validate(ResourceModel $model) : bool
                 } elseif ($validationModel
                     && isset(
                         $validationModel->attributes,
-                        $validationModel->attributes->properties->{$attribute})
+                        $validationModel->attributes->properties->{$attribute}
+                    )
                 ) { //Then attempt to use attribute validation resourceModel first
                     $attributeValidator =
                         $validationModel->attributes->properties->{$attribute};
@@ -297,7 +298,8 @@ public function validate(ResourceModel $model) : bool
                 }
 
                 //Check if operator is allowed
-                if (!$isJSONFilter && !in_array(
+                if (!$isJSONFilter
+                    && !in_array(
                         $operator,
                         Operator::getByClassFlags($operatorClass)
                     )
diff --git a/src/Directive/FilterAttribute.php b/src/Directive/FilterAttribute.php
index c76caf4..de94d7a 100644
--- a/src/Directive/FilterAttribute.php
+++ b/src/Directive/FilterAttribute.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -166,5 +166,4 @@ public function getOperand()
     {
         return $this->operand;
     }
-
 }
diff --git a/src/Directive/FilterJSONAttribute.php b/src/Directive/FilterJSONAttribute.php
index 4bde3e4..cb0bffa 100644
--- a/src/Directive/FilterJSONAttribute.php
+++ b/src/Directive/FilterJSONAttribute.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -59,5 +59,4 @@ public function getKey()
     {
         return $this->key;
     }
-
 }
diff --git a/src/Directive/IncludeResources.php b/src/Directive/IncludeResources.php
index 5752e51..15fb7a9 100644
--- a/src/Directive/IncludeResources.php
+++ b/src/Directive/IncludeResources.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/src/Directive/Page.php b/src/Directive/Page.php
index bd7373d..95d9ce5 100644
--- a/src/Directive/Page.php
+++ b/src/Directive/Page.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/src/Directive/Sort.php b/src/Directive/Sort.php
index 12fdcca..0f04b79 100644
--- a/src/Directive/Sort.php
+++ b/src/Directive/Sort.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -46,7 +46,8 @@ class Sort extends Directive
      * @param bool   $ascending
      */
     public function __construct(
-        $attribute, $ascending = true
+        string $attribute,
+        bool $ascending = true
     ) {
         $this->attribute = $attribute;
         $this->ascending = $ascending;
@@ -125,7 +126,7 @@ public static function parseFromRequest(
     /**
      * @return boolean
      */
-    public function getAscending()
+    public function getAscending() : bool
     {
         return $this->ascending;
     }
@@ -133,7 +134,7 @@ public function getAscending()
     /**
      * @return string
      */
-    public function getAttribute()
+    public function getAttribute() : string
     {
         return $this->attribute;
     }
diff --git a/src/Model.php b/src/Model.php
index 7a783a6..1faed06 100644
--- a/src/Model.php
+++ b/src/Model.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/src/Model/DataSourceTrait.php b/src/Model/DataSourceTrait.php
index c03fd26..2962569 100644
--- a/src/Model/DataSourceTrait.php
+++ b/src/Model/DataSourceTrait.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -388,4 +388,4 @@ function ($directive) {
 
         return $collectionObject;
     }
-}
\ No newline at end of file
+}
diff --git a/src/Model/DirectivesTrait.php b/src/Model/DirectivesTrait.php
index 9ea9d58..55ccafd 100644
--- a/src/Model/DirectivesTrait.php
+++ b/src/Model/DirectivesTrait.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -283,4 +283,4 @@ public function getPrivateAttributes() : array
     {
         return $this->privateAttributes;
     }
-}
\ No newline at end of file
+}
diff --git a/src/Model/RelationshipsTrait.php b/src/Model/RelationshipsTrait.php
index b57c573..368efac 100644
--- a/src/Model/RelationshipsTrait.php
+++ b/src/Model/RelationshipsTrait.php
@@ -1,5 +1,6 @@
 <?php
-/**
+declare(strict_types=1);
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/src/Model/VariableTrait.php b/src/Model/VariableTrait.php
index a8c177c..415a658 100644
--- a/src/Model/VariableTrait.php
+++ b/src/Model/VariableTrait.php
@@ -1,5 +1,6 @@
 <?php
-/**
+declare(strict_types=1);
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -72,4 +73,4 @@ public function issetVariable(string $key) : bool
     {
         return property_exists($this->variables, $key);
     }
-}
\ No newline at end of file
+}
diff --git a/src/ModelTrait.php b/src/ModelTrait.php
index 5748adb..0ff6e04 100644
--- a/src/ModelTrait.php
+++ b/src/ModelTrait.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -29,4 +29,4 @@ trait ModelTrait
      * @var ResourceModel
      */
     protected static $model = null;  //important to define $resourceModel in extended classes
-}
\ No newline at end of file
+}
diff --git a/src/Relationship.php b/src/Relationship.php
index 3aff4c3..769e40a 100644
--- a/src/Relationship.php
+++ b/src/Relationship.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/src/RelationshipResource.php b/src/RelationshipResource.php
index 9869ac9..c64e7de 100644
--- a/src/RelationshipResource.php
+++ b/src/RelationshipResource.php
@@ -1,5 +1,5 @@
 <?php
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/src/Resource.php b/src/Resource.php
index 5919505..73b39a1 100644
--- a/src/Resource.php
+++ b/src/Resource.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -232,11 +232,11 @@ public static function parseFromRecord(
             return null;
         }
 
-        $flagAttributes    = ($flags & Resource::PARSE_ATTRIBUTES) != 0;
-        $flagLinks         = ($flags & Resource::PARSE_LINKS) != 0;
+        $flagAttributes = ($flags & Resource::PARSE_ATTRIBUTES) != 0;
+        $flagLinks = ($flags & Resource::PARSE_LINKS) != 0;
         $flagRelationships = ($flags & Resource::PARSE_RELATIONSHIP) != 0;
-        $flagRelationshipLinks       = ($flags & Resource::PARSE_RELATIONSHIP_LINKS) != 0;
-        $flagRelationshipData        = ($flags & Resource::PARSE_RELATIONSHIP_DATA) != 0;
+        $flagRelationshipLinks = ($flags & Resource::PARSE_RELATIONSHIP_LINKS) != 0;
+        $flagRelationshipData = ($flags & Resource::PARSE_RELATIONSHIP_DATA) != 0;
 
 
         $idAttribute = $model->getIdAttribute();
@@ -255,7 +255,7 @@ public static function parseFromRecord(
         //Initialize resource
         $resource = new $resourceClass(
             $model->getResourceType(),
-            (string) $record->{$idAttribute}
+            (string)$record->{$idAttribute}
         );
 
         //Delete $idAttribute from record's attributes
@@ -266,7 +266,7 @@ public static function parseFromRecord(
             $meta = $record->{Resource::META_MEMBER};
 
             if (is_array($meta) && Util::isArrayAssoc($meta)) {
-                $meta = (object) $meta;
+                $meta = (object)$meta;
             }
 
             if (!is_object($meta)) {
@@ -292,7 +292,7 @@ public static function parseFromRecord(
             }
         }
 
-        if (count((array) $privateAttributes)) {
+        if (count((array)$privateAttributes)) {
             $resource->{'private-attributes'} = $privateAttributes;
         }
 
@@ -303,145 +303,144 @@ public static function parseFromRecord(
         //Attach relationships if resource's relationships are set
 //        if (/*$flagRelationships &&*/ ($relationships = $resourceModel->getRelationships())) {
 
-            $resourceRelationships = new \stdClass();
-            //Parse relationships
-            foreach ($model->getRelationships() ?? [] as $relationshipKey => $relationshipObject) {
-                //Initialize an new relationship entry object
-                $relationshipEntry = new \stdClass();
-
-                //Attach relationship links
-                //TODO RESTORE
-               /* if ($flagRelationshipLinks) {
-                    $relationshipEntry->links = [
-                        'self' => $resourceModel::getSelfLink(
-                            $resource->id . '/relationships/' . $relationshipKey
-                        ),
-                        'related' => $resourceModel::getSelfLink(
-                            $resource->id . '/' . $relationshipKey
-                        )
-                    ];
-                }*/
-
-                $relationshipFlagData = ($relationshipObject->getFlags() & Relationship::FLAG_DATA) != 0;
-
-                /**
-                 * @var ResourceModel
-                 */
-                $relationshipModel   = $relationshipObject->getResourceModel();
-                $relationshipType    = $relationshipObject->getType();
-                $recordDataAttribute = $relationshipObject->getRecordDataAttribute();
-
-                $relationshipResourceType = $relationshipModel->getResourceType();
-
-                //todo Define callback signature to fetch data
-                /**
-                 * @return string[]|RelationshipResource[]
-                 */
-                $dataCallback = function () use (
-                    $relationshipObject,
-                    $resource,
-                    $relationshipKey,
-                    $directives,
-                    $flags
-                ) {
-                    $cb = $relationshipObject->getCallbacks()->{'GET'};
-
-                    return $cb(
-                        $resource->id,
-                        $directives,
-                        $flags // use $flagRelationshipsAttributes to enable/disable parsing of relationship attributes
-                    );
-                };
-                
-                if ($flagRelationships && ($flagRelationshipData || $relationshipFlagData)) {
-                    //Include data only if $flagRelationshipData is true
-                    if ($relationshipType === Relationship::TYPE_TO_ONE) {
-                        $relationshipEntryResource = null;
-
-                        if (isset($record->{$recordDataAttribute}) && $record->{$recordDataAttribute}) { //preloaded
-                            $relationshipEntryResource = $record->{$recordDataAttribute};
-                        } elseif (isset($relationshipObject->getCallbacks()->{'GET'})) { //available from callback
-                            $relationshipEntryResource = $dataCallback();
-                        }
-
-                        if ($relationshipEntryResource !== null) {
-                            //parse relationship resource
-                            if (is_string($relationshipEntryResource)) {
-                                //If returned $relationshipEntryResource is an id string
-                                $relationshipEntry->data = new RelationshipResource(
-                                    $relationshipResourceType,
-                                    (string) $relationshipEntryResource
-                                );
-                            } elseif ($relationshipEntryResource instanceof RelationshipResource) {
-                                //If returned $relationshipEntryResource is RelationshipResource
-                                $relationshipEntry->data = $relationshipEntryResource;
-                            } else {
-                                throw new \Exception(sprintf(
-                                    'Unexpected relationship entry resource of relationship "%s",'
-                                    . ' expecting string or RelationshipResource "%s" given',
-                                    $relationshipKey,
-                                    gettype($relationshipEntryResource)
-                                ));
-                            }
-                        }
-                    } elseif ($relationshipType === Relationship::TYPE_TO_MANY) {
-                        //Initialize
-                        $relationshipEntry->data = [];
-
-                        $relationshipEntryResources = [];
-
-                        if (isset($record->{$recordDataAttribute}) && $record->{$recordDataAttribute}) { //preloaded
-                            $relationshipEntryResources = $record->{$recordDataAttribute};
-                        } elseif (isset($relationshipObject->getCallbacks()->{'GET'})) { //available from callback
-                            $relationshipEntryResources = $dataCallback();
-                        }
+        $resourceRelationships = new \stdClass();
+        //Parse relationships
+        foreach ($model->getRelationships() ?? [] as $relationshipKey => $relationshipObject) {
+            //Initialize an new relationship entry object
+            $relationshipEntry = new \stdClass();
+
+            //Attach relationship links
+            //TODO RESTORE
+            /* if ($flagRelationshipLinks) {
+                 $relationshipEntry->links = [
+                     'self' => $resourceModel::getSelfLink(
+                         $resource->id . '/relationships/' . $relationshipKey
+                     ),
+                     'related' => $resourceModel::getSelfLink(
+                         $resource->id . '/' . $relationshipKey
+                     )
+                 ];
+             }*/
+
+            $relationshipFlagData = ($relationshipObject->getFlags() & Relationship::FLAG_DATA) != 0;
+
+            /**
+             * @var ResourceModel
+             */
+            $relationshipModel = $relationshipObject->getResourceModel();
+            $relationshipType = $relationshipObject->getType();
+            $recordDataAttribute = $relationshipObject->getRecordDataAttribute();
+
+            $relationshipResourceType = $relationshipModel->getResourceType();
+
+            //todo Define callback signature to fetch data
+            /**
+             * @return string[]|RelationshipResource[]
+             */
+            $dataCallback = function () use (
+                $relationshipObject,
+                $resource,
+                $relationshipKey,
+                $directives,
+                $flags
+            ) {
+                $cb = $relationshipObject->getCallbacks()->{'GET'};
 
-                        if (!is_array($relationshipEntryResources)) {
-                            throw new \Exception(sprintf(
-                                'Expecting array for relationship entry resources of relationship "%s"',
-                                $relationshipKey
-                            ));
-                        }
+                return $cb(
+                    $resource->id,
+                    $directives,
+                    $flags // use $flagRelationshipsAttributes to enable/disable parsing of relationship attributes
+                );
+            };
+
+            if ($flagRelationships && ($flagRelationshipData || $relationshipFlagData)) {
+                //Include data only if $flagRelationshipData is true
+                if ($relationshipType === Relationship::TYPE_TO_ONE) {
+                    $relationshipEntryResource = null;
+
+                    if (isset($record->{$recordDataAttribute}) && $record->{$recordDataAttribute}) { //preloaded
+                        $relationshipEntryResource = $record->{$recordDataAttribute};
+                    } elseif (isset($relationshipObject->getCallbacks()->{'GET'})) { //available from callback
+                        $relationshipEntryResource = $dataCallback();
+                    }
 
-                        //Parse relationship resources
-
-                        if (Util::isArrayOf($relationshipEntryResources, 'string')) {
-                            //If returned $relationshipEntryResources are id strings
-                            foreach ($relationshipEntryResources as $relationshipEntryResourceId) {
-                                $relationshipEntry->data[] = new RelationshipResource(
-                                    $relationshipResourceType,
-                                    (string)$relationshipEntryResourceId
-                                );
-                            }
-                        } elseif (Util::isArrayOf($relationshipEntryResources, RelationshipResource::class)) {
-                            //If returned $relationshipEntryResources are RelationshipResource
-                            $relationshipEntry->data = $relationshipEntryResources;
+                    if ($relationshipEntryResource !== null) {
+                        //parse relationship resource
+                        if (is_string($relationshipEntryResource)) {
+                            //If returned $relationshipEntryResource is an id string
+                            $relationshipEntry->data = new RelationshipResource(
+                                $relationshipResourceType,
+                                (string)$relationshipEntryResource
+                            );
+                        } elseif ($relationshipEntryResource instanceof RelationshipResource) {
+                            //If returned $relationshipEntryResource is RelationshipResource
+                            $relationshipEntry->data = $relationshipEntryResource;
                         } else {
                             throw new \Exception(sprintf(
-                                'Unexpected relationship entry resources of relationship "%s",'
+                                'Unexpected relationship entry resource of relationship "%s",'
                                 . ' expecting string or RelationshipResource "%s" given',
                                 $relationshipKey,
-                                gettype($relationshipEntryResources[0])
+                                gettype($relationshipEntryResource)
                             ));
                         }
                     }
-                }
+                } elseif ($relationshipType === Relationship::TYPE_TO_MANY) {
+                    //Initialize
+                    $relationshipEntry->data = [];
+
+                    $relationshipEntryResources = [];
+
+                    if (isset($record->{$recordDataAttribute}) && $record->{$recordDataAttribute}) { //preloaded
+                        $relationshipEntryResources = $record->{$recordDataAttribute};
+                    } elseif (isset($relationshipObject->getCallbacks()->{'GET'})) { //available from callback
+                        $relationshipEntryResources = $dataCallback();
+                    }
+
+                    if (!is_array($relationshipEntryResources)) {
+                        throw new \Exception(sprintf(
+                            'Expecting array for relationship entry resources of relationship "%s"',
+                            $relationshipKey
+                        ));
+                    }
+
+                    //Parse relationship resources
 
-                if ($recordDataAttribute !== null) {
-                    //Unset this attribute (MUST not be visible in resource's attributes)
-                    unset($record->{$recordDataAttribute});
+                    if (Util::isArrayOf($relationshipEntryResources, 'string')) {
+                        //If returned $relationshipEntryResources are id strings
+                        foreach ($relationshipEntryResources as $relationshipEntryResourceId) {
+                            $relationshipEntry->data[] = new RelationshipResource(
+                                $relationshipResourceType,
+                                (string)$relationshipEntryResourceId
+                            );
+                        }
+                    } elseif (Util::isArrayOf($relationshipEntryResources, RelationshipResource::class)) {
+                        //If returned $relationshipEntryResources are RelationshipResource
+                        $relationshipEntry->data = $relationshipEntryResources;
+                    } else {
+                        throw new \Exception(sprintf(
+                            'Unexpected relationship entry resources of relationship "%s",'
+                            . ' expecting string or RelationshipResource "%s" given',
+                            $relationshipKey,
+                            gettype($relationshipEntryResources[0])
+                        ));
+                    }
                 }
+            }
 
-                //Push relationship to relationships
-                $resourceRelationships->{$relationshipKey} = $relationshipEntry;
+            if ($recordDataAttribute !== null) {
+                //Unset this attribute (MUST not be visible in resource's attributes)
+                unset($record->{$recordDataAttribute});
             }
 
+            //Push relationship to relationships
+            $resourceRelationships->{$relationshipKey} = $relationshipEntry;
+        }
 
-            //Attach only if set
-            if ($flagRelationships) {
-                $resource->relationships = $resourceRelationships;
-            }
-        //}
+
+        //Attach only if set
+        if ($flagRelationships) {
+            $resource->relationships = $resourceRelationships;
+        }
 
         //Attach resource attributes
         if ($flagAttributes) {
diff --git a/src/ResourceModel.php b/src/ResourceModel.php
index d665f09..12d5c78 100644
--- a/src/ResourceModel.php
+++ b/src/ResourceModel.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -93,7 +93,6 @@ public function __construct(string $resourceType, DataSource $dataSource = null)
 
         //Set default prepareRecord method as an empty method
         $this->prepareRecord = function (array &$record) {
-
         };
 
         $this->dataSource = $dataSource;
diff --git a/src/ValidationModel.php b/src/ValidationModel.php
index 91d2ee9..d5d30f7 100644
--- a/src/ValidationModel.php
+++ b/src/ValidationModel.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/tests/APP/DataSource/MemoryDataSource.php b/tests/APP/DataSource/MemoryDataSource.php
index ae1b5aa..58c81cb 100644
--- a/tests/APP/DataSource/MemoryDataSource.php
+++ b/tests/APP/DataSource/MemoryDataSource.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/tests/APP/Models/Company.php b/tests/APP/Models/Company.php
index ddf63a6..0752de2 100644
--- a/tests/APP/Models/Company.php
+++ b/tests/APP/Models/Company.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/tests/APP/Models/Group.php b/tests/APP/Models/Group.php
index 6146233..6542a68 100644
--- a/tests/APP/Models/Group.php
+++ b/tests/APP/Models/Group.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/tests/APP/Models/Tag.php b/tests/APP/Models/Tag.php
index 4752578..7c16b01 100644
--- a/tests/APP/Models/Tag.php
+++ b/tests/APP/Models/Tag.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/tests/APP/Models/User.php b/tests/APP/Models/User.php
index 0b45e8c..7b09adb 100644
--- a/tests/APP/Models/User.php
+++ b/tests/APP/Models/User.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index 225deda..add71ad 100644
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/tests/src/Controller/ControllerTest.php b/tests/src/Controller/ControllerTest.php
index 66539df..417fff2 100644
--- a/tests/src/Controller/ControllerTest.php
+++ b/tests/src/Controller/ControllerTest.php
@@ -1,5 +1,5 @@
 <?php
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/tests/src/Controller/GetByIdTest.php b/tests/src/Controller/GetByIdTest.php
index d757e76..9a39936 100644
--- a/tests/src/Controller/GetByIdTest.php
+++ b/tests/src/Controller/GetByIdTest.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/tests/src/Controller/GetTest.php b/tests/src/Controller/GetTest.php
index 93393dc..cc765e2 100644
--- a/tests/src/Controller/GetTest.php
+++ b/tests/src/Controller/GetTest.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/tests/src/Directive/AdditionalParametersTest.php b/tests/src/Directive/AdditionalParametersTest.php
index ad322a7..300e37f 100644
--- a/tests/src/Directive/AdditionalParametersTest.php
+++ b/tests/src/Directive/AdditionalParametersTest.php
@@ -1,5 +1,5 @@
 <?php
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/tests/src/Directive/AdditionalRelationshipsParameterTest.php b/tests/src/Directive/AdditionalRelationshipsParameterTest.php
index d6031e9..21b7ef0 100644
--- a/tests/src/Directive/AdditionalRelationshipsParameterTest.php
+++ b/tests/src/Directive/AdditionalRelationshipsParameterTest.php
@@ -1,5 +1,5 @@
 <?php
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/tests/src/Directive/DirectiveTest.php b/tests/src/Directive/DirectiveTest.php
index ee2dbc5..72ced80 100644
--- a/tests/src/Directive/DirectiveTest.php
+++ b/tests/src/Directive/DirectiveTest.php
@@ -1,5 +1,5 @@
 <?php
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/tests/src/Directive/FieldsTest.php b/tests/src/Directive/FieldsTest.php
index 3117cfd..aaa271a 100644
--- a/tests/src/Directive/FieldsTest.php
+++ b/tests/src/Directive/FieldsTest.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/tests/src/Directive/FilterAttributeTest.php b/tests/src/Directive/FilterAttributeTest.php
index c412099..dec43ba 100644
--- a/tests/src/Directive/FilterAttributeTest.php
+++ b/tests/src/Directive/FilterAttributeTest.php
@@ -1,5 +1,5 @@
 <?php
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/tests/src/Directive/FilterJSONAttributeTest.php b/tests/src/Directive/FilterJSONAttributeTest.php
index e9a2ecd..01f36af 100644
--- a/tests/src/Directive/FilterJSONAttributeTest.php
+++ b/tests/src/Directive/FilterJSONAttributeTest.php
@@ -1,5 +1,5 @@
 <?php
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/tests/src/Directive/FilterTest.php b/tests/src/Directive/FilterTest.php
index 828f7a1..451bb04 100644
--- a/tests/src/Directive/FilterTest.php
+++ b/tests/src/Directive/FilterTest.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/tests/src/Directive/IncludeResourcesTest.php b/tests/src/Directive/IncludeResourcesTest.php
index 41efbbb..dcd8e62 100644
--- a/tests/src/Directive/IncludeResourcesTest.php
+++ b/tests/src/Directive/IncludeResourcesTest.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/tests/src/Directive/PageTest.php b/tests/src/Directive/PageTest.php
index 41b8682..29a742a 100644
--- a/tests/src/Directive/PageTest.php
+++ b/tests/src/Directive/PageTest.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/tests/src/Directive/SortTest.php b/tests/src/Directive/SortTest.php
index 9da8213..a208287 100644
--- a/tests/src/Directive/SortTest.php
+++ b/tests/src/Directive/SortTest.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/tests/src/Model/RelationshipsTraitTest.php b/tests/src/Model/RelationshipsTraitTest.php
index 4587b96..ca1cb6c 100644
--- a/tests/src/Model/RelationshipsTraitTest.php
+++ b/tests/src/Model/RelationshipsTraitTest.php
@@ -1,5 +1,6 @@
 <?php
-/**
+declare(strict_types=1);
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/tests/src/Model/VariableTraitTest.php b/tests/src/Model/VariableTraitTest.php
index 7d8d96d..d09308e 100644
--- a/tests/src/Model/VariableTraitTest.php
+++ b/tests/src/Model/VariableTraitTest.php
@@ -1,6 +1,6 @@
 <?php
 declare(strict_types=1);
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/tests/src/ModelTest.php b/tests/src/ModelTest.php
index da658a1..14c4174 100644
--- a/tests/src/ModelTest.php
+++ b/tests/src/ModelTest.php
@@ -1,5 +1,5 @@
 <?php
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/tests/src/RelationshipTest.php b/tests/src/RelationshipTest.php
index 64e8076..877bb97 100644
--- a/tests/src/RelationshipTest.php
+++ b/tests/src/RelationshipTest.php
@@ -1,5 +1,6 @@
 <?php
-/**
+declare(strict_types=1);
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/tests/src/ResourceModelTest.php b/tests/src/ResourceModelTest.php
index 96262ba..08f39e8 100644
--- a/tests/src/ResourceModelTest.php
+++ b/tests/src/ResourceModelTest.php
@@ -1,5 +1,5 @@
 <?php
-/**
+/*
  * Copyright 2015-2016 Xenofon Spafaridis
  *
  * Licensed under the Apache License, Version 2.0 (the "License");