Redirect back with errors and input in custom request class : Laravel 5

I had some original code that shows like below with form validation and saving process in MySQL Database.

Original Code

public function store(Request $request)
{
    $v = \Validator::make($request->all(), [
        'Category' => 'required|unique:tblcategory|max:25|min:5'
    ]);

    if ($v->fails()) {
        return \Redirect::back()
                    ->withErrors($v)
                    ->withInput();
    }
    ...
    //code to save the record in database is here....
    ...
}

Then I followed this article and modified the above function and now it looks like below.

public function store(CategoryRequest $request)
{

    ...
    //code to save the record in database is here....
    ...
}

and below is the Request class

class CategoryRequest extends Request
{
    protected $redirect = \Redirect::back()->withErrors($v)->withInput();
    public function authorize()
    {
        return false;
    }
    public function rules()
    {
        return [
            'Category' => 'required|unique:tblcategory|max:25|min:5'
        ];
    }
}

Error Details

syntax error, unexpected '(', expecting ',' or ';'

This error is coming at below line.

protected $redirect = \Redirect::back()->withErrors($v)->withInput();

Am I missing something ?

via Chebli Mohamed