根據來自 scrapy 的信號更新主線程內的 PyQt5 Gui

Question

我有一個非常基本的蜘蛛，它看起來像來自 scrapy 測試蜘蛛的跟隨蜘蛛。

import re

import scrapy.signals
from scrapy.http import Request, HtmlResponse
from scrapy.linkextractors import LinkExtractor
from six.moves.urllib.parse import urlparse

from page import Page


class ZenSpider( scrapy.Spider ) :
    def __init__(self) :
        super().__init__()

    name = 'followall'
    custom_settings = {
        'CLOSESPIDER_PAGECOUNT' : 2,
        "FEEDS" : {
            "items.csv" : {"format" : "csv"},
        },
    }

    def __init__(self, **kw) :
        super( ZenSpider, self ).__init__( **kw )
        url = kw.get( 'url' ) or kw.get( 'domain' ) or 'http://scrapinghub.com/'
        if not url.startswith( 'http://' ) and not url.startswith( 'https://' ) :
            url = 'http://%s/' % url
        self.url = url
        self.allowed_domains = [re.sub(r'^www\.', '', urlparse(url).hostname)]
        self.link_extractor = LinkExtractor()

    def start_requests(self):
        return [Request(self.url, callback=self.parse, dont_filter=True)]

    def parse(self, response):
        """Parse a PageItem and all requests to follow

        @url http://www.scrapinghub.com/
        @returns items 1 1
        @returns requests 1
        @scrapes url title foo
        """
        page = self._get_item(response)
        r = [page]
        r.extend(self._extract_requests(response))
        return r

    def _get_item(self, response):
        items = []
        item = Page(
            url=response.url,
            size=str( len( response.body ) ),
            status=response.status,
            # content_type=response.request.headers.get('Content-Type'),
            # encoding=response.request.headers.get('encoding'),
            # referer=response.request.headers.get('Referer'),
        )
        self._set_title( item, response )
        self._set_description( item, response )
        return item

    def _extract_requests(self, response):
        r = []
        if isinstance(response, HtmlResponse):
            links = self.link_extractor.extract_links( response )
            r.extend( Request( x.url, callback=self.parse ) for x in links )
        return r

    def _set_title(self, page, response) :
        if isinstance( response, HtmlResponse ) :
            title = response.xpath( "//title/text()" ).extract()
            if title :
                page['title'] = title[0]

    def _set_description(self, page, response) :
        if isinstance( response, HtmlResponse ) :
            description = response.xpath( "//meta[@name='description']/@content" ).extract()
            if description :
                page['description'] = description[0]

我從下面的腳本中調用這個蜘蛛。 蜘蛛使用 CrawlRunner class 運行，當它獲取一個項目時會發出一個信號作為 p.signals.connect ，然后調用方法 crawler_results 並打印抓取的項目。

據我了解，我無法將爬行移動到它自己的 class 中，因為這樣信號就無法與 PyQt5 一起使用

import scrapy
from PyQt5 import QtWidgets, QtCore, QtGui
from PyQt5.QtCore import QRunnable, pyqtSlot, QThread, pyqtSignal, QTimer
from PyQt5.QtWidgets import QTableWidgetItem, QLabel
from scrapy import signals
from scrapy.crawler import CrawlerProcess, CrawlerRunner
from twisted.internet import reactor
from scrapy.utils.log import configure_logging

from Layout import Ui_MainWindow
from ZenSpider import ZenSpider


class MainWindow( QtWidgets.QMainWindow, Ui_MainWindow ) :

    def __init__(self, parent=None) :
        super(MainWindow, self).__init__()

        self.setupUi( self )
        self.pushButton.pressed.connect( self.on_url_entered )

    def crawler_results(self, item) :
        print( "SCRAPED AN ITEM" )
        ##Do Something here ##

    def on_url_entered(self) :
        # global userInput
        # userInput = self.urlbar.text()
        configure_logging()
        runner = CrawlerRunner()
        runner.crawl(ZenSpider, domain="google.com.au")
        for p in runner.crawlers :
            p.signals.connect(self.crawler_results, signal=signals.item_scraped)
        reactor.run()

if __name__ == "__main__" :
    app = QtWidgets.QApplication( [] )
    main_window = MainWindow()
    main_window.show()
    app.exec_()

我有一個簡單的 QTableWidget 和一個按鈕的布局

# -*- coding: utf-8 -*-

# Form implementation generated from reading ui file 'basic.ui'
#
# Created by: PyQt5 UI code generator 5.14.2
#
# WARNING! All changes made in this file will be lost!


from PyQt5 import QtCore, QtGui, QtWidgets


class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(1034, 803)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.tableWidget = QtWidgets.QTableWidget(self.centralwidget)
        self.tableWidget.setGeometry(QtCore.QRect(140, 200, 831, 401))
        self.tableWidget.setObjectName("tableWidget")
        self.tableWidget.setColumnCount(1)
        self.tableWidget.setRowCount(0)
        item = QtWidgets.QTableWidgetItem()
        self.tableWidget.setHorizontalHeaderItem(0, item)
        self.pushButton = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton.setGeometry(QtCore.QRect(880, 610, 89, 25))
        self.pushButton.setObjectName("pushButton")
        MainWindow.setCentralWidget(self.centralwidget)
        self.statusbar = QtWidgets.QStatusBar(MainWindow)
        self.statusbar.setObjectName("statusbar")
        MainWindow.setStatusBar(self.statusbar)

        self.retranslateUi(MainWindow)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        item = self.tableWidget.horizontalHeaderItem(0)
        item.setText(_translate("MainWindow", "URL"))
        self.pushButton.setText(_translate("MainWindow", "Start"))


if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    MainWindow = QtWidgets.QMainWindow()
    ui = Ui_MainWindow()
    ui.setupUi(MainWindow)
    MainWindow.show()
    sys.exit(app.exec_())

當我按下按鈕時，我可以看到爬蟲正在運行並進入 crawler_results 方法，因為它打印了抓取的項目。 蜘蛛將每個項目返回為以下值

{'size': '164125',
 'status': 200,
 'title': 'Google Advanced Search',
 'url': 'https://www.google.com.au/advanced_search?hl=en-AU&authuser=0'}

頁面只是我的 scrapy 項目

import scrapy

class Page(scrapy.Item):
    url = scrapy.Field()
    size = scrapy.Field()
    status = scrapy.Field()
    title = scrapy.Field()

我的問題是如何將這些數據轉換為 GUI 並讓它在蜘蛛運行時自動刷新。 這意味着每次抓取一個項目時，GUI 都會更新，然后蜘蛛會繼續。

到目前為止我已經探索過

1. 使用 scrapy 延遲沒有太多運氣
2. 插槽/信號，但無法更新 GUI。
3. 一個 Qtimer function 每秒更新一次 GUI，但這又不會產生任何結果。

任何幫助深表感謝

Answer 1

您必須安裝與 Qt 事件循環兼容的反應器，例如使用：

• qt5reactor ( python -m pip install qt5reactor ),
• qt-reactor ( python -m pip install qt-reactor )

import sys

from PyQt5 import QtWidgets, QtCore, QtGui

import qt5reactor
# import qreactor

from scrapy import signals
from scrapy.crawler import CrawlerRunner
from scrapy.utils.log import configure_logging

import twisted

from Layout import Ui_MainWindow
from ZenSpider import ZenSpider


class MainWindow(QtWidgets.QMainWindow, Ui_MainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__()

        self.setupUi(self)
        self.pushButton.pressed.connect(self.on_url_entered)
        self.tableWidget.horizontalHeader().setSectionResizeMode(
            QtWidgets.QHeaderView.ResizeToContents
        )

    def crawler_results(self, item):
        row = self.tableWidget.rowCount()

        url = item["url"]

        it = QtWidgets.QTableWidgetItem(url)
        self.tableWidget.insertRow(row)
        self.tableWidget.setItem(row, 0, it)

    def on_url_entered(self):
        configure_logging()
        runner = CrawlerRunner()
        runner.crawl(ZenSpider, domain="google.com.au")
        for p in runner.crawlers:
            p.signals.connect(self.crawler_results, signal=signals.item_scraped)

    def closeEvent(self, event):
        super(MainWindow, self).closeEvent(event)
        twisted.internet.reactor.stop()


if __name__ == "__main__":
    app = QtWidgets.QApplication([])

    qt5reactor.install()
    # qreactor.install()

    main_window = MainWindow()
    main_window.show()
    twisted.internet.reactor.run()