如何在Scrapy中使用file Pipeline获取下载后的文件路径？

ITEM_PIPELINES = {
    'scrapy.pipelines.files.FilesPipeline': 1,
}

import scrapy

class MyItem(scrapy.Item):
    file_urls = scrapy.Field()
    file_paths = scrapy.Field()

from scrapy import Spider
from myproject.items import MyItem

class MySpider(Spider):
    name = 'myspider'
    start_urls = ['http://example.com']

    def parse(self, response):
        item = MyItem()
        item['file_urls'] = [response.urljoin('path/to/file')]
        yield item

from scrapy.pipelines.files import FilesPipeline
from urllib.parse import urlparse

class MyFilesPipeline(FilesPipeline):
    def file_path(self, request, response=None, info=None):
        path = urlparse(request.url).path
        return path

    def item_completed(self, results, item, info):
        if 'file_urls' in item:
            file_paths = [x['path'] for ok, x in results if ok]
            if file_paths:
                item['file_paths'] = file_paths
        return item

ITEM_PIPELINES = {
    'myproject.pipelines.MyFilesPipeline': 2,
}