标签：selector 用法 name tle 正则表达式 找不到 -o href doc
# 命令行输入:scrapy shell +链接,会自动请求url,得到的相应默认为response,开启命令行交互模式
scrapy shell http://doc.scrapy.org/en/latest/_static/selectors-sample1.html
In [1]: response#response为默认相应
Out[1]: <200 https://doc.scrapy.org/en/latest/_static/selectors-sample1.html>
In [2]: response.text#response.text相应的源代码
# 标准结构图如下:
response.text = ‘‘‘
<html>
<head>
<base href=‘http://example.com/‘ />
<title>Example website</title>
</head>
<body>
<div id=‘images‘>
<a href=‘image1.html‘>Name: My image 1 <br /><img src=‘image1_thumb.jpg‘ /></a>
<a href=‘image2.html‘>Name: My image 2 <br /><img src=‘image2_thumb.jpg‘ /></a>
<a href=‘image3.html‘>Name: My image 3 <br /><img src=‘image3_thumb.jpg‘ /></a>
<a href=‘image4.html‘>Name: My image 4 <br /><img src=‘image4_thumb.jpg‘ /></a>
<a href=‘image5.html‘>Name: My image 5 <br /><img src=‘image5_thumb.jpg‘ /></a>
</div>
</body>
</html>
‘‘‘
# 1:使用选择器response.selector.xpath()/response.selector.css()
In [5]: response.selector.xpath(‘//title/text()‘).extract_first()
Out[5]: ‘Example website‘
In [6]: response.selector.css(‘title::text‘).extract_first()
Out[6]: ‘Example website‘
# 2:使用选择器也可以简写为:response.xpath() / response.css()
In [9]: response.css(‘title::text‘)
Out[9]: [<Selector xpath=‘descendant-or-self::title/text()‘ data=‘Example website‘>]
In [10]: response.xpath(‘//title/text()‘)
Out[10]: [<Selector xpath=‘//title/text()‘ data=‘Example website‘>]
# 3:以上可知使用.xpath() .css()返回仍然是一个选择器,若要提取里面的数据,可以用extract()提取全部,extract_first提取首个
In [7]: response.xpath(‘//title/text()‘).extract_first()
Out[7]: ‘Example website‘
In [8]: response.css(‘title::text‘).extract_first()
Out[8]: ‘Example website‘
# 4:可以循环进行选择
# 获取div标签里面,id = ‘images‘的元素, 然后继续查找img标签属性为src的内容,最终提取出来
# 就是说,包含关系用中括号[],从属关系用斜杠 /
In [14]: response.xpath("//div[@id=‘images‘]").css(‘img::attr(src)‘).extract()
Out[14]:
[‘image1_thumb.jpg‘,
‘image2_thumb.jpg‘,
‘image3_thumb.jpg‘,
‘image4_thumb.jpg‘,
‘image5_thumb.jpg‘]
# extract_first还有default属性,如果查找不到对应的元素即返回default指定的值
In [16]: response.xpath("//div[@id=‘images‘]").css(‘img::attr(src)‘).extract_first(default=‘‘)
Out[16]: ‘image1_thumb.jpg‘
# 查找a标签下,属性为href的元素,提取出来
In [18]: response.xpath(‘//a/@href‘).extract()
Out[18]: [‘image1.html‘, ‘image2.html‘, ‘image3.html‘, ‘image4.html‘, ‘image5.html‘]
In [19]: response.css(‘a::attr(href)‘).extract()
Out[19]: [‘image1.html‘, ‘image2.html‘, ‘image3.html‘, ‘image4.html‘, ‘image5.html‘]
# 5:查找标签的文本
In [20]: response.xpath(‘//a/text()‘).extract()
Out[20]:
[‘Name: My image 1 ‘,
‘Name: My image 2 ‘,
‘Name: My image 3 ‘,
‘Name: My image 4 ‘,
‘Name: My image 5 ‘]
In [21]: response.css(‘a::text‘).extract()
Out[21]:
[‘Name: My image 1 ‘,
‘Name: My image 2 ‘,
‘Name: My image 3 ‘,
‘Name: My image 4 ‘,
‘Name: My image 5 ‘]
# 6:选取标签的属性
In [34]: response.css(‘a::attr(href)‘).extract()
Out[34]: [‘image1.html‘, ‘image2.html‘, ‘image3.html‘, ‘image4.html‘, ‘image5.html‘]
In [39]: response.xpath(‘//a/@href‘).extract()
Out[39]: [‘image1.html‘, ‘image2.html‘, ‘image3.html‘, ‘image4.html‘, ‘image5.html‘]
# 查找属性名称为href 包含image的标签的属性
In [24]: response.xpath(‘//a[contains(@href,"image")]/@href‘).extract()
Out[24]: [‘image1.html‘, ‘image2.html‘, ‘image3.html‘, ‘image4.html‘, ‘image5.html‘]
In [25]: response.css(‘a[href*=image]::attr(href)‘).extract()
Out[25]: [‘image1.html‘, ‘image2.html‘, ‘image3.html‘, ‘image4.html‘, ‘image5.html‘]
# 查找a标签里面属性名为href,包含image,包含img,属性为src的属性
In [27]: response.xpath(‘//a[contains(@href,"image")]/img/@src‘).extract()
Out[27]:
[‘image1_thumb.jpg‘,
‘image2_thumb.jpg‘,
‘image3_thumb.jpg‘,
‘image4_thumb.jpg‘,
‘image5_thumb.jpg‘]
In [28]: response.css(‘a[href*=image] img::attr(src)‘).extract()
Out[28]:
[‘image1_thumb.jpg‘,
‘image2_thumb.jpg‘,
‘image3_thumb.jpg‘,
‘image4_thumb.jpg‘,
‘image5_thumb.jpg‘]
# 7:可配合正则表达式,re_first表示取第一个满足正则表达式的
In [30]: response.css(‘a::text‘).re(‘Name\:(.*)‘)
Out[30]:
[‘ My image 1 ‘,
‘ My image 2 ‘,
‘ My image 3 ‘,
‘ My image 4 ‘,
‘ My image 5 ‘]
In [31]: response.css(‘a::text‘).re_first(‘Name\:(.*)‘)
Out[31]: ‘ My image 1 ‘
In [32]: response.css(‘a::text‘).re_first(‘Name\:(.*)‘).strip()#去除空格
Out[32]: ‘My image 1‘标签：selector 用法 name tle 正则表达式 找不到 -o href doc
原文地址：https://www.cnblogs.com/myiuni/p/10745441.html
