做getallAttributes（）的正确方法是什么

Question

我正在尝试读取给定元素的属性（attributes）。 我想提取一个包含所有属性名值对的字典。你知道吗

我目前正在做的是使用regex并列出所有属性值。但这里的问题是，它只显示属性的值，而不显示名称：

attributes = node.xpath("@*")
print attributes
print len(attributes)
for att in attributes:
    print att

示例输出类似于：

<Selector xpath='@*' data=u'1'>
<Selector xpath='@*' data=u'2761554'>
<Selector xpath='@*' data=u'1431756540503'>

有人能推荐一种列出元素所有属性的方法吗？
我正在使用python/scrapy。你知道吗

Answer 1

对于XPath，您可以使用name()和属性作为参数。你知道吗

1. 计数元素的属性count(@*)
2. 对于每个属性位置，使用@*[position]提取名称和值

meta元素的scrapy shell会话示例：

$ scrapy shell "https://stackoverflow.com/questions/30295249/what-would-be-the-right-way-of-doing-getallattributes"
2015-05-18 10:47:28+0200 [default] DEBUG: Crawled (200) <GET https://stackoverflow.com/questions/30295249/what-would-be-the-right-way-of-doing-getallattributes> (referer: None)
[s] Available Scrapy objects:
[s]   crawler    <scrapy.crawler.Crawler object at 0x7f732bf4b190>
[s]   item       {}
[s]   request    <GET https://stackoverflow.com/questions/30295249/what-would-be-the-right-way-of-doing-getallattributes>
[s]   response   <200 https://stackoverflow.com/questions/30295249/what-would-be-the-right-way-of-doing-getallattributes>
[s]   settings   <scrapy.settings.Settings object at 0x7f732bf3ffd0>
[s]   spider     <DefaultSpider 'default' at 0x7f73268eead0>
[s] Useful shortcuts:
[s]   shelp()           Shell help (print this help)
[s]   fetch(req_or_url) Fetch request (or URL) and update local objects
[s]   view(response)    View response in a browser

In [1]: import pprint
In [2]: for meta  in response.xpath('//meta[@*]'):
   ...:     nbattr = int(float(meta.xpath('count(@*)').extract()[0]))
   ...:     pprint.pprint(dict((meta.xpath('name(@*[%d])' % i).extract()[0], meta.xpath('@*[%d]' % i).extract()[0]) for i in range(1, nbattr+1)))
   ...:     print
   ...:     
{u'content': u'summary', u'name': u'twitter:card'}

{u'content': u'stackoverflow.com', u'name': u'twitter:domain'}

{u'content': u'website', u'property': u'og:type'}

{u'content': u'https://cdn.sstatic.net/stackoverflow/img/apple-touch-icon@2.png?v=ea71a5211a91&a',
 u'itemprop': u'image primaryImageOfPage',
 u'property': u'og:image'}

{u'content': u'what would be the right way of doing getallAttributes()',
 u'itemprop': u'title name',
 u'name': u'twitter:title',
 u'property': u'og:title'}

{u'content': u'I am trying to read the property(attributes) of given element .\n\nI want to extract the Dictionary of all the attributes name-value pair..\n\nwhat i am currently doing is i am using regex and listting...',
 u'itemprop': u'description',
 u'name': u'twitter:description',
 u'property': u'og:description'}

{u'content': u'http://stackoverflow.com/questions/30295249/what-would-be-the-right-way-of-doing-getallattributes',
 u'property': u'og:url'}

{u'content': u'US', u'name': u'twitter:app:country'}

{u'content': u'Stack Exchange iOS', u'name': u'twitter:app:name:iphone'}

{u'content': u'871299723', u'name': u'twitter:app:id:iphone'}

{u'content': u'se-zaphod://stackoverflow.com/questions/30295249/what-would-be-the-right-way-of-doing-getallattributes',
 u'name': u'twitter:app:url:iphone'}

{u'content': u'Stack Exchange iOS', u'name': u'twitter:app:name:ipad'}

{u'content': u'871299723', u'name': u'twitter:app:id:ipad'}

{u'content': u'se-zaphod://stackoverflow.com/questions/30295249/what-would-be-the-right-way-of-doing-getallattributes',
 u'name': u'twitter:app:url:ipad'}

{u'content': u'Stack Exchange Android',
 u'name': u'twitter:app:name:googleplay'}

{u'content': u'http://stackoverflow.com/questions/30295249/what-would-be-the-right-way-of-doing-getallattributes',
 u'name': u'twitter:app:url:googleplay'}

{u'content': u'com.stackexchange.marvin',
 u'name': u'twitter:app:id:googleplay'}

我使用了类似的技术in this blogpost来提取微观数据：

>>> for item in selector.xpath('.//*[@itemscope]'):
...     print "Item:", item.xpath('@itemtype').extract()
...     for property in item.xpath('.//*[@itemprop]'):
...         print "Property:",
...         print property.xpath('@itemprop').extract(),
...         print property.xpath('string(.)').extract()
...         for position, attribute in enumerate(property.xpath('@*'), start=1):
...             print "attribute: name=%s; value=%s" % (
...                 property.xpath('name(@*[%d])' % position).extract(),
...                 attribute.extract())
...         print
...     print
... 
Item: [u'http://schema.org/Movie']
Property: [u'name'] [u'Avatar']
attribute: name=[u'itemprop']; value=name

Property: [u'director'] [u'n  Director: James Cameron n(born August 16, 1954)n  ']
attribute: name=[u'itemprop']; value=director
attribute: name=[u'itemscope']; value=
attribute: name=[u'itemtype']; value=http://schema.org/Person

Property: [u'name'] [u'James Cameron']
attribute: name=[u'itemprop']; value=name

Property: [u'birthDate'] [u'August 16, 1954']
attribute: name=[u'itemprop']; value=birthDate
attribute: name=[u'datetime']; value=1954-08-16

Property: [u'genre'] [u'Science fiction']
attribute: name=[u'itemprop']; value=genre

Property: [u'trailer'] [u'Trailer']
attribute: name=[u'href']; value=../movies/avatar-theatrical-trailer.html
attribute: name=[u'itemprop']; value=trailer


Item: [u'http://schema.org/Person']
Property: [u'name'] [u'James Cameron']
attribute: name=[u'itemprop']; value=name

Property: [u'birthDate'] [u'August 16, 1954']
attribute: name=[u'itemprop']; value=birthDate
attribute: name=[u'datetime']; value=1954-08-16

>>>