php - 1055 Expression #3 of SELECT list is not in GROUP BY clause error in ManyToMany relationship laravel 5.3 -

i have post model this:

class post extends model {         protected $primarykey = 'post_id';         public function tags ()         {             return $this->belongstomany('app\tag');         }  } 

and tag model:

class tag extends model {         public function posts ()         {             return $this->belongstomany('app\post');         }          public function tagscount ()         {             return $this->belongstomany('app\post')                 ->selectraw('count(pt_id) count')                 ->groupby('tag_id');         }          public function gettagscountattribute()         {             if ( ! array_key_exists('tagscount', $this->relations)) $this->load('tagscount');              $related = $this->getrelation('tagscount')->first();              return ($related) ? $related->count : 0;         } } 

(pt_id column primary key field in post_tag pivot table).

as see ,there manytomany relation between post , tag models.

for count related tags of specific post ,i added tagscount() , gettagscountattribute() methods tag model.

now suppose want tags count of specific post :

$post = post::find($post_id)->get(); return $post->tagscount 

it worked me in laravel 5.2 (and older versions) after upgrading laravel 5.3 , below error shown:

sqlstate[42000]: syntax error or access violation: 1055 expression #3 of select list not in group clause , contains nonaggregated column 'aids.post_tag.post_id' not functionally dependent on columns in group clause; incompatible sql_mode=only_full_group_by (sql: select count(pt_id) count, `post_tag`.`tag_id` `pivot_tag_id`, `post_tag`.`post_id` `pivot_post_id` `posts` inner join `post_tag` on `posts`.`post_id` = `post_tag`.`post_id` `post_tag`.`tag_id` in (145) , `posts`.`deleted_at` null group `post_tag`.`tag_id`) 

what problem , how can solve ?

this related mysql 5.7

long story short, 1 solution try changing config/database.php true false:

'mysql' => [     'strict' => false, //behave 5.6     //'strict' => true //behave 5.7 ],  

for more info, see here: https://stackoverflow.com/a/39251942/2238694