Fixed problem with nullable relations.

src/Relation/Traits/FieldTrait.php

@@ -55,30 +55,31 @@ protected function ensureField(Entity $target, string $name, Field $outer, bool
         $outer->setReferenced(true);
 
         if ($target->getFields()->has($name)) {
-            // field already exists and defined by the user
-            return;
-        }
+            // field already exists and defined previously or by the user
+            $field = $target->getFields()->get($name);
+        } else {
+            $field = new Field();
+            $field->setColumn($name);
+            $field->setTypecast($outer->getTypecast());
 
-        $field = new Field();
-        $field->setColumn($name);
-        $field->setTypecast($outer->getTypecast());
+            switch ($outer->getType()) {
+                case 'primary':
+                    $field->setType('int');
+                    break;
+                case 'bigPrimary':
+                    $field->setType('bigint');
+                    break;
+                default:
+                    $field->setType($outer->getType());
+            }
 
-        switch ($outer->getType()) {
-            case 'primary':
-                $field->setType('int');
-                break;
-            case 'bigPrimary':
-                $field->setType('bigint');
-                break;
-            default:
-                $field->setType($outer->getType());
+            $target->getFields()->set($name, $field);
         }
 
+        // If on of relations requires nullable type then making it nullable
         if ($nullable) {
             $field->getOptions()->set(Column::OPT_NULLABLE, true);
         }
-
-        $target->getFields()->set($name, $field);
     }
 
     /**

src/Relation/Traits/MorphTrait.php

@@ -73,24 +73,25 @@ protected function findOuterKey(Registry $registry, string $interface): array
     /**
      * @param Entity $target
      * @param string $name
-     * @param int    $lenght
+     * @param int    $length
      * @param bool   $nullable
      */
-    protected function ensureMorphField(Entity $target, string $name, int $lenght, bool $nullable = false): void
+    protected function ensureMorphField(Entity $target, string $name, int $length, bool $nullable = false): void
     {
         if ($target->getFields()->has($name)) {
-            // field already exists and defined by the user
-            return;
-        }
+            // field already exists and defined previously or by the user
+            $field = $target->getFields()->get($name);
+        } else {
+            $field = new Field();
+            $field->setColumn($name);
+            $field->setType(sprintf('string(%s)', $length));
 
-        $field = new Field();
-        $field->setColumn($name);
-        $field->setType(sprintf('string(%s)', $lenght));
+            $target->getFields()->set($name, $field);
+        }
 
+        // If on of relations requires nullable type then making it nullable
         if ($nullable) {
             $field->getOptions()->set(Column::OPT_NULLABLE, true);
         }
-
-        $target->getFields()->set($name, $field);
     }
 }

tests/Schema/Relation/BelongsToRelationTest.php

@@ -251,4 +251,67 @@ public function testInverseToHasMany(): void
             $schema['author'][Schema::RELATIONS]['post'][Relation::SCHEMA][Relation::INNER_KEY]
         );
     }
+
+    public function testRelatedFieldShouldBeCreated()
+    {
+        $e = Post::define();
+        $u = Author::define();
+
+        $e->getRelations()->get('author')->setInverse('post', 'hasMany');
+
+        $r = new Registry($this->dbal);
+        $r->register($e)->linkTable($e, 'default', 'post');
+        $r->register($u)->linkTable($u, 'default', 'author');
+
+        (new Compiler())->compile($r, [
+            new GenerateRelations(['belongsTo' => new BelongsTo(), 'hasMany'   => new HasMany()]),
+        ]);
+
+        $this->assertTrue($e->getFields()->has('author_id'));
+        $this->assertFalse($e->getFields()->get('author_id')->getOptions()->has('nullable'));
+    }
+
+    public function testRelatedFieldShouldBeNullableIfBelongsToHasNullableOption()
+    {
+        $e = Post::define();
+        $u = Author::define();
+
+        $e->getRelations()->get('author')->setInverse('post', 'hasMany')->getOptions()->set('nullable', true);
+
+        $r = new Registry($this->dbal);
+        $r->register($e)->linkTable($e, 'default', 'post');
+        $r->register($u)->linkTable($u, 'default', 'author');
+
+        (new Compiler())->compile($r, [
+            new GenerateRelations(['belongsTo' => new BelongsTo(), 'hasMany' => new HasMany()]),
+        ]);
+
+        $this->assertTrue($e->getFields()->has('author_id'));
+        $this->assertTrue($e->getFields()->get('author_id')->getOptions()->get('nullable'));
+    }
+
+    public function testRelatedFieldShouldBeNullableIHasManyHasNullableOption()
+    {
+        $e = Post::define();
+        $u = Author::define();
+
+        $hasMany = (new \Cycle\Schema\Definition\Relation())
+            ->setTarget(Post::class)
+            ->setType('hasMany')
+            ->setInverse('author', 'belongsTo');
+        $hasMany->getOptions()->set('nullable', true);
+        $u->getRelations()->set('posts', $hasMany);
+        $e->getRelations()->get('author')->setInverse('post', 'hasMany');
+
+        $r = new Registry($this->dbal);
+        $r->register($e)->linkTable($e, 'default', 'post');
+        $r->register($u)->linkTable($u, 'default', 'author');
+
+        (new Compiler())->compile($r, [
+            new GenerateRelations(['belongsTo' => new BelongsTo(), 'hasMany' => new HasMany()]),
+        ]);
+
+        $this->assertTrue($e->getFields()->has('author_id'));
+        $this->assertTrue($e->getFields()->get('author_id')->getOptions()->get('nullable'));
+    }
 }