Fix filtering null values in where() with Meilisearch (#901)

Author: tobz-nz

src/Engines/MeilisearchEngine.php

@@ -182,6 +182,10 @@ protected function filters(Builder $builder)
                 return sprintf('%s=%s', $key, $value ? 'true' : 'false');
             }
 
+            if (is_null($value)) {
+                return sprintf('%s %s', $key, 'IS NULL');
+            }
+
             return is_numeric($value)
                 ? sprintf('%s=%s', $key, $value)
                 : sprintf('%s="%s"', $key, $value);

tests/Feature/Engines/MeilisearchEngineTest.php

@@ -206,12 +206,13 @@ public function test_where_in_conditions_are_applied()
         $builder = new Builder(new SearchableUser, '');
         $builder->where('foo', 'bar');
         $builder->where('bar', 'baz');
+        $builder->where('baz', null);
         $builder->whereIn('qux', [1, 2]);
         $builder->whereIn('quux', [1, 2]);
 
         $this->client->shouldReceive('index')->once()->with('users')->andReturn($index = m::mock(Indexes::class));
         $index->shouldReceive('rawSearch')->once()->with($builder->query, array_filter([
-            'filter' => 'foo="bar" AND bar="baz" AND qux IN [1, 2] AND quux IN [1, 2]',
+            'filter' => 'foo="bar" AND bar="baz" AND baz IS NULL AND qux IN [1, 2] AND quux IN [1, 2]',
             'hitsPerPage' => $builder->limit,
         ]))->andReturn([]);