如何使用所需名称在laravel中上传文件

Question

我在上传文件时遇到错误，它说未定义变量：filenametostore。

这是我的控制器：

if(!$validator->fails()){
    $cate = Product::where('name','=',$request->product_name)->first();
    if($cate){
        $arr = array('status'=>'false-1','message'=>'Product name already exist');
    }else{
        $cat = new Product();
        $cat->name = $request->product_name;
        $cat->category_id = $request->product_category;
        $cat->brand_id = $request->product_brand;
        $cat->quantity = $request->product_quantity;
        $cat->buy_per_piece = $request->product_buying_per_piece;
        $cat->sell_per_piece = $request->product_selling_per_piece;
        if($request->hasFile('thumbnail')){
            $filenameExt = $request->file('thumbnail')->getClientOriginalName();
            $filename = pathinfo($filenameExt,PATHINFO_FILENAME);
            $extension = $request->file('thumbnail')->getClientOriginalExtension();
            $filenametostore = $filename.'_'.time().'.'.$extension;
            $request->file('thumbnail')->move(public_path('images'), $filenametostore);
        }
        $cat->image = $filenametostore;
        $cat->save();

        $arr = array('status'=>'true','message'=>'Successfully Inserted');
    }
}else{
    $arr = array('status'=>'false','message'=>$validator->errors()->all());
}

请帮助我纠正错误