Laravel query groubBy condition - laravel

Question

I have a dB query where I would like to groupBy() only when conditions are met without using union because of pagination.
Unfortunately groupBy() seems to only work when called on the entire query outside of the loop.
This was made for dynamic filtering from $filterArr. Depending on the array I need to select from different columns of the table.
When the $key=='pattern' I would need the distinct results from its column.
the query looks something like this
select `col_1`, `col_2`, `col_3`
from `mytable`
where (`color` LIKE ? or `pattern` LIKE ? or `style` LIKE ?)
group by `col_2` //<< i need this only for 'pattern' above and not the entire query
Heres the model:
// $filterArr example
// Array ( [color] => grey [pattern] => stripe )
$query = DB::table('mytable');
$query = $query->select(array('col_1', 'col_2', 'col_3'), DB::raw('count(*) as total'));
$query = $query->where(function($query) use ($filterArr){
$ii = 0;
foreach ($filterArr as $key => $value) {
if ($key=='color'){
$column = 'color';
}else if ($key=='style'){
$column = 'style';
}else if ($key=='pattern'){
$column = 'pattern';
$query = $query->groupBy('col_2'); // << !! does not work
}
if($ii==0){
$query = $query->where($column, 'LIKE', '%'.$value.'%');
}
else{
$query = $query->orWhere($column, 'LIKE', '%'.$value.'%');
}
$ii++;
}
});
$query = $query->orderBy('col_2', 'asc')->simplePaginate(30);

Answer 1

I think you can simplify your code a bit:
$query = DB::table('mytable');
$query = $query->select(array('col_1', 'col_2', 'col_3'), DB::raw('count(*) as total'));
$query = $query->where(
collect($filterArr)
->only(['color','style','pattern'])
->map(function ($value, $key) {
return [ $key, 'like', '%'.$value.'%', 'OR' ];
})->all()
)->when(array_key_exists('pattern', $filterArr), function ($query) {
return $query->groupBy('col_2');
});
$query = $query->orderBy('col_2', 'asc')->simplePaginate(30);