Laravel - strtolower() expects parameter 1 to be string, object given

Question

i am trying to group tags by first character

return $tags->select('id', 'title')
    ->orderBy('title','asc')
    ->groupBy(function($item, $key) { 
        return substr($item['title'], 1, 1); 
    })
    ->get();

but it returns this error

strtolower() expects parameter 1 to be string, object given

Answer 1

您不能使用闭包对查询进行分组，只能使用结果集合：

...->orderBy(...)->get()->groupBy(...);