NameError：name＆＃39; QWebPage＆＃39;没有定义

Question

我是Python新手，我想了解为什么会出现以下错误：

Traceback (most recent call last):
File "WebScraper.py", line 10, in <module>
    class Render(QWebPage):  
NameError: name 'QWebPage' is not defined

以下是代码：

import sys  
from PyQt5.QtGui import *  
from PyQt5.QtCore import *  
from PyQt5.QtWebEngineWidgets import *  
from lxml import html 

#Take this class for granted.Just use result of rendering.
class Render(QWebPage):  
  def __init__(self, url):  
    self.app = QApplication(sys.argv)  
    QWebPage.__init__(self)  
    self.loadFinished.connect(self._loadFinished)  
    self.mainFrame().load(QUrl(url))  
    self.app.exec_()  

  def _loadFinished(self, result):  
    self.frame = self.mainFrame()  
    self.app.quit()  

url = 'http://pycoders.com/archive/'  
r = Render(url)  
result = r.frame.toHtml()
#This step is important.Converting QString to Ascii for lxml to process
archive_links = html.fromstring(str(result.toAscii()))
print(archive_links)

我理解__init__充当构造函数，但为什么不将它设置为self？所以我需要将其更改为QWebPage.x = self？

Answer 1

您未导入QWebPage

尝试将此导入添加到脚本顶部：

from PyQt5.QtWebKitWidgets import QWebPage

Answer 2

您使用的是什么版本的PyQt5？请注意，启动PyQt5.9，QtWebKitWidgets（以及QtWebKit）不再可用（不建议使用），导致您收到错误。

让我并置两个渲染函数，一个使用旧的（PyQt4），另一个使用最新的PyQt5：

使用PyQt4，请注意 QWebPage 的使用情况，当然还有导入

from PyQt4.QtCore import *
from PyQt4.QtGui import *
from PyQt4.QtWebKit import *

class Render(QWebPage):
    """Render HTML with PyQt4 WebEngine."""  
    def __init__(self, url):  
        self.app = QApplication(sys.argv)  
        QWebPage.__init__(self)  
        self.loadFinished.connect(self._loadFinished)  
        self.mainFrame().load(QUrl(url))  
        self.app.exec_()  

    def _loadFinished(self, result):  
        self.frame = self.mainFrame()  
        self.app.quit()

使用PyQt5，请注意使用 QWebEngineView 而不是 QWebPage ，当然还有导入

 from PyQt5.QtCore import QEventLoop
 from PyQt5.QtWebEngineWidgets import QWebEngineView
 from PyQt5.QtWidgets import QApplication

    class Render(QWebEngineView):
        """Render HTML with PyQt5 WebEngine."""

        def __init__(self, html):
            self.html = None
            self.app = QApplication(sys.argv)
            QWebEngineView.__init__(self)
            self.loadFinished.connect(self._loadFinished)
            self.setHtml(html)
            while self.html is None:
                self.app.processEvents(
                    QEventLoop.ExcludeUserInputEvents |
                    QEventLoop.ExcludeSocketNotifiers |
                    QEventLoop.WaitForMoreEvents)
            self.app.quit()