Python，将数据从列表传递到lxml中的xpath

Question

Having trouble passing data from a list into xpath, in lxml.

See these lines, below:

formatted_xpath = str(xpath_string[x])
current_data = xpath_html.xpath("string(formatted_xpath)")
# current_data = xpath_html.xpath("string(//*[@class='title-container clearfix']/h1)")

It works fine if I use this, with a hard coded xpath in def brandScrapePage:

current_data = xpath_html.xpath("string(//*[@class='title-container clearfix']/h1)")

But, it won't work if I use my formatted_xpath variable. Does not find anything. I know formatted_xpath is correct. Looks good when I print it. Not sure what the issue is.

CODE:

xpath_string = ["//*[@class='title-container clearfix']/h2"]


def pageSource(line):
    response = urllib2.urlopen(line)
    html = response.read()
    html = html.decode('utf-8', 'ignore').encode('utf-8')
    return html


def brandScrapePage(brand_html, x):
    xpath_html = etree.HTML(brand_html)
    formatted_xpath = str(xpath_string[x])
    current_data = xpath_html.xpath("string(formatted_xpath)")
    # current_data = xpath_html.xpath("string(//*[@class='title-container clearfix']/h1)")

def main():

    f = open(home_dir + url_file).readlines()
    for line in f:
        for x in xrange(0, len(field_names)):
            current_html = pageSource(line)
            brandScrapePage(current_html, x)


if __name__ == '__main__':
    main()

Answer 1

The problem is that you are basically having a formatted_xpath string but meant to create a placeholder and format the string with an actual value:

current_data = xpath_html.xpath("string(%s)" % formatted_xpath)

Or, with format() :

current_data = xpath_html.xpath("string({})".format(formatted_xpath))