Python CGI Script(使用 XML 和 mindom)无法提取空数据

Question

这部分代码解析XML，以便输出到网页上的屏幕。

for counter in range(100):
    try:
        for item in BlekkoSearchResultsXML.getElementsByTagName('item'):
            Blekko_PageTitle = item.getElementsByTagName('title')[counter].firstChild.toxml(encoding="utf-8")
            Blekko_PageDesc = item.getElementsByTagName('description')[counter].firstChild.toxml(encoding="utf-8")
            Blekko_DisplayURL = item.getElementsByTagName('guid')[counter].firstChild.toxml(encoding="utf-8")
            Blekko_URL = item.getElementsByTagName('link')[counter].firstChild.toxml(encoding="utf-8")
            print "<h2>" + Blekko_PageTitle + "</h2>"
            print Blekko_PageDesc + "<br />"
            print Blekko_DisplayURL + "<br />"
            print Blekko_URL + "<br />"
    except IndexError:
        break

但是，如果脚本遇到一组空XML标记，即如果页面没有页面标题或描述，则脚本失败，并显示错误消息:

AttributeError: 'NoneType' object has no attribute 'toxml' 
      args = ("'NoneType' object has no attribute 'toxml'",)

正在解析的XML代码片段:

<item>
        <title>SUSHI FANLISTING</title>
        <link>http://sushi.perfectdrug.net/</link>
        <guid>http://sushi.perfectdrug.net/</guid>
        <description>This is the official...</description>
        </item>

我尝试使用try/except语句，但没有成功:

try:
    Blekko_PageTitle = item.getElementsByTagName('title')[counter].firstChild.toxml(encoding="utf-8")
except Blekko_PageTitle = None:
    Blekko_PageTitle = "No page title provided..."

Answer 1

你做的except是错误的:它捕获被引发的Exception对象。你想要

except AttributeError:

或者，使用条件语句:

if Blekko_PageTitle = None:
    ...
else:
    ...