scrapy选择器主要用法
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# 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‘
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