XPath choose one if both exist - html

Question

I have something like
<li class="ProductPrice">
<span class="Regular Price">80.00</span>
<span class="Sale Price">50.00</span>
</li>
<li class="ProductPrice">
<span class="Regular Price">100.00</span>
</li>
where some items might not have the Sale Price span.
I would like to extract the current retail price, where I would select the Sale Price or if both Sale and Regular Price exist, choose Sale Price only.
I'm new to XPath, so I'm not sure how this if-else could be translated.

Answer 1

I would like to extract the current retail price, where I would select
the Sale Price or if both Sale and Regular Price exist, choose Sale
Price only.
If you know that the Sale price will always come after the Regular price, use the XPath expression
span[#class = 'Regular Price' or #class = 'Sale Price'][last()]
In XPath 2.0 you can use this approach even if you don't know the order:
(span[#class = 'Sale Price'], span[#class = 'Regular Price'])[1]

Answer 2

An XSLT-1.0 solution is a bit more complicated:
<xsl:template match="li">
<xsl:choose>
<xsl:when test="span/#class='Sale Price'">
<xsl:value-of select="span[#class='Sale Price']" />
</xsl:when>
<xsl:otherwise>
<xsl:value-of select="span[#class='Regular Price']" />
</xsl:otherwise>
</xsl:choose>
</xsl:template>
So if you have XPath-2.0 or above available you could use the following:
<xsl:template match="li">
<xsl:value-of select="if (span/#class='Sale Price') then (span[#class='Sale Price']) else (span[#class='Regular Price'])" />
</xsl:template>
The output of both solutions is the same:
<?xml version="1.0" encoding="UTF-8"?>
50.00
100.00
The logic is not exactly what you desired, but it is close to.

Answer 3

You can use lxml module in python. It is by far the easiest module which I have used.
from lxml import html
data = '''<li class="ProductPrice">
<span class="Regular Price">80.00</span>
<span class="Sale Price">50.00</span>
</li>
<li class="ProductPrice">
<span class="Regular Price">100.00</span>
</li>
'''
#make the html object
tree = html.fromstring(data)
li = tree.xpath('//li') #get all the li tags
for i in li:
sp = i.xpath('.//span[contains(#class,"Sale Price")]/text()')
rp = i.xpath('.//span[contains(#class,"Regular Price")]/text()')
if sp:
print('Price is :',sp[0])
else:
print('Price is :',rp[0])
What I did was, to extract sale price and check if it is there. If it is present then program will print that else program will print regular price.
Note
Remember to put (.) in the xpath when playing with seperate elements.
The result of the xpath always comes as list.
For any query do put up a comment.