Unset relation when null (singular) or empty array (plural)

README.MD

@@ -372,8 +372,10 @@ $attributes = [
         'name'     => 'Björn Brala',
         'homepage' => 'https://github.com/bbrala',
     ],
+    'co-author' => null,
     'date'    => '2018-12-02 15:26:32',
     'content' => 'JSON:API was originally drafted in May 2013 by Yehuda Katz...',
+    'media' => [],
     'tags'    => [
         1,
         15,
@@ -399,6 +401,12 @@ echo json_encode($itemDocument, JSON_PRETTY_PRINT);
                     "id": "f1a775ef-9407-40ba-93ff-7bd737888dc6"
                 }
             },
+            "co-author": {
+                "data": null
+            },
+            "media": {
+                "data": []
+            },
             "tags": {
                 "data": [{
                     "type": "tag",
@@ -426,6 +434,7 @@ echo json_encode($itemDocument, JSON_PRETTY_PRINT);
 
 As you can see in this example, relations can be hydrated by id, or by an associative array with an id and more attributes.
 If the item is hydrated using an associative array, it will be included in the resulting json unless `setOmitIncluded(true)` is called on the relation.
+You can unset a relation by passing `null` for singular relations or an empty array for plural relations.
 
 N.B. Morph relations require a 'type' attribute to be present in the data in order to know which type of item should be created.
 

src/ItemHydrator.php

@@ -6,6 +6,8 @@
 use Illuminate\Support\Str;
 use Swis\JsonApi\Client\Exceptions\HydrationException;
 use Swis\JsonApi\Client\Interfaces\ItemInterface;
+use Swis\JsonApi\Client\Interfaces\ManyRelationInterface;
+use Swis\JsonApi\Client\Interfaces\OneRelationInterface;
 use Swis\JsonApi\Client\Interfaces\TypeMapperInterface;
 use Swis\JsonApi\Client\Relations\HasManyRelation;
 use Swis\JsonApi\Client\Relations\HasOneRelation;
@@ -76,6 +78,16 @@ protected function fillRelations(ItemInterface $item, array $attributes): void
 
             $relation = $this->getRelationFromItem($item, $availableRelation);
 
+            // The relation should be unset
+            if (
+                ($relation instanceof OneRelationInterface && $attributes[$availableRelation] === null) ||
+                ($relation instanceof ManyRelationInterface && $attributes[$availableRelation] === [])
+            ) {
+                $relation->dissociate();
+
+                return;
+            }
+
             // It is a valid relation
             if ($relation instanceof HasOneRelation) {
                 $this->hydrateHasOneRelation($relation, $attributes[$availableRelation]);

tests/ItemHydratorTest.php

@@ -102,6 +102,28 @@ public function it_hydrates_hasone_relationships_with_attributes()
         $this->assertArrayHasKey('hasone_relation', $item->toJsonApiArray()['relationships']);
     }
 
+    /**
+     * @test
+     */
+    public function it_dissociates_hasone_relationships_when_null()
+    {
+        $data = [
+            'hasone_relation' => null,
+        ];
+
+        $item = new WithRelationshipItem();
+        $item = $this->getItemHydrator()->hydrate($item, $data);
+
+        /** @var \Swis\JsonApi\Client\Relations\HasOneRelation $hasOne */
+        $hasOne = $item->getRelation('hasone_relation');
+        $this->assertInstanceOf(HasOneRelation::class, $hasOne);
+
+        $this->assertNull($hasOne->getIncluded());
+
+        $this->assertArrayHasKey('hasone_relation', $item->toJsonApiArray()['relationships']);
+        $this->assertNull($item->toJsonApiArray()['relationships']['hasone_relation']['data']);
+    }
+
     /**
      * @test
      */
@@ -174,6 +196,28 @@ public function it_hydrates_hasmany_relationships_with_attributes()
         $this->assertArrayHasKey('hasmany_relation', $item->toJsonApiArray()['relationships']);
     }
 
+    /**
+     * @test
+     */
+    public function it_dissociates_hasmany_relationships_when_empty_array()
+    {
+        $data = [
+            'hasmany_relation' => [],
+        ];
+
+        $item = new WithRelationshipItem();
+        $item = $this->getItemHydrator()->hydrate($item, $data);
+
+        /** @var \Swis\JsonApi\Client\Relations\HasManyRelation $hasMany */
+        $hasMany = $item->getRelation('hasmany_relation');
+        $this->assertInstanceOf(HasManyRelation::class, $hasMany);
+
+        $this->assertTrue($hasMany->getIncluded()->isEmpty());
+
+        $this->assertArrayHasKey('hasmany_relation', $item->toJsonApiArray()['relationships']);
+        $this->assertSame([], $item->toJsonApiArray()['relationships']['hasmany_relation']['data']);
+    }
+
     /**
      * @test
      */
@@ -228,6 +272,28 @@ public function it_hydrates_morphto_relationships_with_attributes()
         $this->assertArrayHasKey('morphto_relation', $item->toJsonApiArray()['relationships']);
     }
 
+    /**
+     * @test
+     */
+    public function it_dissociates_morphto_relationships_when_null()
+    {
+        $data = [
+            'morphto_relation' => null,
+        ];
+
+        $item = new WithRelationshipItem();
+        $item = $this->getItemHydrator()->hydrate($item, $data);
+
+        /** @var \Swis\JsonApi\Client\Relations\MorphToRelation $morphTo */
+        $morphTo = $item->getRelation('morphto_relation');
+        $this->assertInstanceOf(MorphToRelation::class, $morphTo);
+
+        $this->assertNull($morphTo->getIncluded());
+
+        $this->assertArrayHasKey('morphto_relation', $item->toJsonApiArray()['relationships']);
+        $this->assertNull($item->toJsonApiArray()['relationships']['morphto_relation']['data']);
+    }
+
     /**
      * @test
      */
@@ -350,6 +416,28 @@ public function it_hydrates_morphtomany_relationships_with_attributes()
         $this->assertArrayHasKey('morphtomany_relation', $item->toJsonApiArray()['relationships']);
     }
 
+    /**
+     * @test
+     */
+    public function it_dissociates_morphtomany_relationships_when_empty_array()
+    {
+        $data = [
+            'morphtomany_relation' => [],
+        ];
+
+        $item = new WithRelationshipItem();
+        $item = $this->getItemHydrator()->hydrate($item, $data);
+
+        /** @var \Swis\JsonApi\Client\Relations\MorphToManyRelation $morphToMany */
+        $morphToMany = $item->getRelation('morphtomany_relation');
+        $this->assertInstanceOf(MorphToManyRelation::class, $morphToMany);
+
+        $this->assertTrue($morphToMany->getIncluded()->isEmpty());
+
+        $this->assertArrayHasKey('morphtomany_relation', $item->toJsonApiArray()['relationships']);
+        $this->assertSame([], $item->toJsonApiArray()['relationships']['morphtomany_relation']['data']);
+    }
+
     /**
      * @test
      */