Python eTree Parser 没有附加元素

Question

看看我的日志，看看它是怎么说我从 Postgres 返回的行已经从字符串变成了元素(我打印了字符串，打印了元素，打印了 isElement bool 值!)当我尝试附加它时，错误是它不是一个元素。呼，呼。

import sys
from HTMLParser import HTMLParser
from xml.etree import cElementTree as etree
import xml.etree.ElementTree as ET
from xml.etree.ElementTree import Element, SubElement, tostring
import psycopg2
import psycopg2.extras

def main():
    # Connect to an existing database
    conn = psycopg2.connect(dbname="**", user="**", password="**", host="/tmp/", port="**")

    # Open a cursor to perform database operations
    cur = conn.cursor(cursor_factory = psycopg2.extras.RealDictCursor)

    cur.execute("SELECT * FROM landingpagedata;")
    rows = cur.fetchall()

    class LinksParser(HTMLParser):
      def __init__(self):
          HTMLParser.__init__(self)
          self.tb = etree.TreeBuilder()

      def handle_starttag(self, tag, attributes):
          self.tb.start(tag, dict(attributes))

      def handle_endtag(self, tag):
          self.tb.end(tag)

      def handle_data(self, data):
          self.tb.data(data)

      def close(self):
          HTMLParser.close(self)
          return self.tb.close()

    template = 'template.html'



    # parser.feed(open('landingIndex.html').read()) #for testing
    # root = parser.close()

    for row in rows:
        parser = LinksParser()

        parser.feed(open(template).read())
        root = parser.close()




        #title
        title = root.find(".//title")
        title.text = row['title']

        #headline
        h1_id_headline = root.find(".//h1")
        h1_id_headline.text = row['h1_id_headline']
        # print row['h1_id_headline']

        #intro
        p_class_intro = root.find(".//p[@class='intro']")
        p_class_intro.text = row['p_class_intro']
        # print row['p_class_intro']

问题就出在这里!

        #recommended
        p_class_recommendedbackground = root.find(".//div[@class='recommended_background_div']")
        print p_class_recommendedbackground
        p_class_recommendedbackground.clear()
        newElement = ET.fromstring(row['p_class_recommendedbackground'])
        print row['p_class_recommendedbackground']
        print ET.iselement(newElement)
        p_class_recommendedbackground.append(newElement)

        html = tostring(root)
        f = open(row['page_name'], 'w').close()
        f = open(row['page_name'], 'w')
        f.write(html)
        f.close()
        # f = ''
        # html = ''
        parser.reset()
        root = ''

    # Close communication with the database
    cur.close()
    conn.close()

if __name__ == "__main__":
  main()

我的日志是这样的:

{background: url(/images/courses/azRealEstate.png) center no-repeat;}
<Element 'div' at 0x10a999720>
<p class="recommended_background">Materials are are aimed to all aspiring real estate sales associates who wish to obtain the Arizona Real Estate Salesperson license, which is provided by the <a href="http://www.re.state.az.us/" style="text-decoration: underline;">Arizona Department of Real Estate</a>.</p>
True
Traceback (most recent call last):
  File "/Users/Morgan13/Programming/LandingPageBuilder/landingPages/landingBuilderTest.py", line 108, in <module> main()
  File "/Users/Morgan13/Programming/LandingPageBuilder/landingPages/landingBuilderTest.py", line 84, in main
    p_class_recommendedbackground.append(newElement)
TypeError: must be Element, not Element
[Finished in 0.1s with exit code 1]

Answer 1

我可以这样重现错误消息:

from xml.etree import cElementTree as etree
import xml.etree.ElementTree as ET

croot = etree.Element('root')
child = ET.Element('child')
croot.append(child)
# TypeError: must be Element, not Element

问题的根本原因是我们将 ElementTree 的 cElementTree 实现与 xml.etree.ElementTree 实现混合在一起 元素树。永远不要让两人相遇。

所以解决方法就是选择一个，比如 etree，然后替换所有出现的另一个(例如，用 etree 替换 ET) .