Do not add relations without data to JSON API array

If the relation does not have any data, we should not serialize it as having empty data (i.e. null or empty array).

Author: JaZo

src/Item.php

@@ -130,26 +130,27 @@ public function getRelationships(): array
         $relationships = [];
 
         foreach ($this->getRelations() as $name => $relation) {
+            if (!$relation->hasIncluded()) {
+                continue;
+            }
+
             if ($relation instanceof OneRelationInterface) {
-                $relationships[$name] = ['data' => null];
+                $relationships[$name]['data'] = null;
 
                 if ($relation->getIncluded() !== null) {
-                    $relationships[$name] = [
-                        'data' => [
-                            'type' => $relation->getIncluded()->getType(),
-                            'id' => $relation->getIncluded()->getId(),
-                        ],
+                    $relationships[$name]['data'] = [
+                        'type' => $relation->getIncluded()->getType(),
+                        'id' => $relation->getIncluded()->getId(),
                     ];
                 }
             } elseif ($relation instanceof ManyRelationInterface) {
                 $relationships[$name]['data'] = [];
 
                 foreach ($relation->getIncluded() as $item) {
-                    $relationships[$name]['data'][] =
-                        [
-                            'type' => $item->getType(),
-                            'id' => $item->getId(),
-                        ];
+                    $relationships[$name]['data'][] = [
+                        'type' => $item->getType(),
+                        'id' => $item->getId(),
+                    ];
                 }
             }
         }

tests/ItemTest.php

@@ -119,6 +119,24 @@ public function is_adds_empty_hasone_relation_in_to_json_api_array()
         );
     }
 
+    /**
+     * @test
+     */
+    public function is_does_not_add_hasone_relation_without_data_in_to_json_api_array()
+    {
+        $item = new WithRelationshipItem();
+        $item->setId('1234');
+        $item->hasoneRelation();
+
+        $this->assertSame(
+            [
+                'type' => 'item-with-relationship',
+                'id' => '1234',
+            ],
+            $item->toJsonApiArray()
+        );
+    }
+
     /**
      * @test
      */
@@ -170,6 +188,24 @@ public function is_adds_empty_hasmany_relation_in_to_json_api_array()
         );
     }
 
+    /**
+     * @test
+     */
+    public function is_does_not_add_hasmany_relation_without_data_in_to_json_api_array()
+    {
+        $item = new WithRelationshipItem();
+        $item->setId('1234');
+        $item->hasmanyRelation();
+
+        $this->assertSame(
+            [
+                'type' => 'item-with-relationship',
+                'id' => '1234',
+            ],
+            $item->toJsonApiArray()
+        );
+    }
+
     /**
      * @test
      */
@@ -219,6 +255,24 @@ public function is_adds_empty_morphto_relation_in_to_json_api_array()
         );
     }
 
+    /**
+     * @test
+     */
+    public function is_does_not_add_morphto_relation_without_data_in_to_json_api_array()
+    {
+        $item = new WithRelationshipItem();
+        $item->setId('1234');
+        $item->morphtoRelation();
+
+        $this->assertSame(
+            [
+                'type' => 'item-with-relationship',
+                'id' => '1234',
+            ],
+            $item->toJsonApiArray()
+        );
+    }
+
     /**
      * @test
      */
@@ -270,6 +324,24 @@ public function is_adds_empty_morphtomany_relation_in_to_json_api_array()
         );
     }
 
+    /**
+     * @test
+     */
+    public function is_does_not_add_morphtomany_relation_without_data_in_to_json_api_array()
+    {
+        $item = new WithRelationshipItem();
+        $item->setId('1234');
+        $item->morphtomanyRelation();
+
+        $this->assertSame(
+            [
+                'type' => 'item-with-relationship',
+                'id' => '1234',
+            ],
+            $item->toJsonApiArray()
+        );
+    }
+
     /**
      * @test
      */