Question

我正在编写一个简单的python web爬虫。我尝试使用Xpath过滤页面。这是目标页面的一部分。

<p class="mt12">21 
  <span class="line">|</span>low 18
  <span class="line">|</span>north
  <span class="line">|</span>2016
</p>

 <p class="mt12">22
  <span class="line">|</span>low 19
  <span class="line">|</span>2018
</p>

有些项目有三个描述，有些有四个。如何使用Xpath检查元素是否存在？我想提取所有描述，如：

# if element four exists get span four
good['year'] = goods.xpath("p[@class='mt12']/text()[4]")
# else get span three
good['year'] = goods.xpath("p[@class='mt12']/text()[3]")

Answer 1

尝试使用以下代码：

good['year'] = goods.xpath("p[@class='mt12']/text()[4]") or goods.xpath("p[@class='mt12']/text()[3]")

它应该返回text()[4]如果它存在（非空字符串）或text()[3]否则

更新

如果"p[@class='mt12']/text()[4]"表达式返回异常，您可以应用try / except阻止，如下所示：

try:
    good['year'] = goods.xpath("p[@class='mt12']/text()[4]")
except IndexError:
    good['year'] = goods.xpath("p[@class='mt12']/text()[3]")

Python Xpath如何检查元素是否存在？

1 个答案: