高级搜索与多对多的关系在laravel

我想为我的网站创建一个高级搜索。

我有一个与书籍有多对多关系的类别(我的主要模型)

我如何搜索通过类别与选择表单

我的代码在控制器

 public function advancedSearch(Request $request){
        $book = Book::query();
        if($request->get('name')){
            $name = $request->get('name');
            $book->where('name', 'like', '%'.$name.'%');
        }
        if($request->get('author')){
            $author = $request->get('author');
            $book->where('author', 'like', '%'.$author.'%');
        }
        if($request->get('category')){
            // MY QUESTION
        }
        $books = $book->get();
        $category = Category::lists('name','id');
        return view('search')->with('book',$books)->with('title','Search')->with('category',$category);
    }

和我的形式是

{!! Form::open(['method' => 'get' , 'url' => '/search/advanced']) !!}
          <div class="form-group  col-md-3">
              {!! Form::text('name',Input::old('name'),['class' => 'form-control input-sm col-md-3','placeholder'=>'Name']) !!}
          </div>
          <div class="form-group  col-md-3">
              {!! Form::text('author',Input::old('author'),['class' => 'form-control input-sm col-md-3','placeholder'=>'Author']) !!}
          </div>
          <div class="form-group  col-md-3">
              {!! Form::select('category[]',$category,'Select Category',['class' => 'form-control selectpicker input-sm col-md-3','placeholder'=>'Author','multiple']) !!}
          </div>
          <input class="btn btn-default" type="submit" name="btn" value="search">
{!! Form::close() !!}