teachers.php:
namespace app\admin\model;
use think\Model;

class Teachers extends Model
{
public function students(){
return $this->belongsToMany('Students','s_t','s_id','t_id');
}
}
students.php:
namespace app\admin\model;

use think\Model;

class Students extends Model
{
public function teachers(){
return $this->belongsToMany('Teachers','s_t','t_id','s_id');
}
}

teachers表：id,name,gender; students表：id,name,gender,hobby; 中间表：id,s_id,t_id;

index.php:
$s = Students::get(1);
$s->teachers()->save(['id'=>14,'name'=>'god','gender'=>0]);

运行结果，teachers表有添加1条记录，但中间表没有，而且提示：缺少关联表数据， 求大神帮帮我！！