Html XPath 查询：从标签中获取属性 href
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XPath Query: get attribute href from a tag
提问by user3239713
I want to use XPath to get the hrefattribute from an a-tag, but it has two occurrences within the same file. How am I getting along?
I need to check IF there is an hrefattribute with value $street/object, I have got this code and it does not work:
我想使用 XPathhref从a-tag获取属性，但它在同一个文件中出现了两次。我相处得怎么样？我需要检查是否有href值为 $street/object的属性，我有这个代码但它不起作用：
$product_photo = $xpath->query("//a[contains(@href,'{$object_street}fotos/')][1]");
$product_360 = $xpath->query("//a[contains(@href,'{$object_street}360-fotos/')][1]");
$product_blueprint = $xpath->query("//a[contains(@href,'{$object_street}plattegrond/')][1]");
$product_video = $xpath->query("//a[contains(@href,'{$object_street}video/')][1]");
It does not return anything at all. Who can help me out?
它根本不返回任何东西。谁能帮帮我？
回答by mockinterface
For the following HTML document:
对于以下 HTML 文档：
<html>
<body>
<a href="http://www.example.com">Example</a>
<a href="http://www.stackoverflow.com">SO</a>
</body>
</html>
The xpath query /html/body//a/@href(or simply //a/@href) will return:
xpath 查询/html/body//a/@href（或简单地//a/@href）将返回：
http://www.example.com
http://www.stackoverflow.com
To select a specific instance use /html/body//a[N]/@href,
要选择特定的实例使用/html/body//a[N]/@href，
$ /html/body//a[2]/@href
http://www.stackoverflow.com
To test for strings contained in the attribute and return the attribute itself place the check on the tag not on the attribute:
要测试属性中包含的字符串并返回属性本身，请检查标签而不是属性：
$ /html/body//a[contains(@href,'example')]/@href
http://www.example.com
Mixing the two:
两者混合：
$ /html/body//a[contains(@href,'com')][2]/@href
http://www.stackoverflow.com
回答by Rahul Saxena
The answer shared by @mockinterface is correct. Although I would like to add my 2 cents to it.
@mockinterface 分享的答案是正确的。虽然我想加上我的 2 美分。
If someone is using frameworks like scrapythe you will have to use /html/body//a[contains(@href,'com')][2]/@hrefalong with get() like this:
如果有人使用像scrapy你这样的框架，你将不得不/html/body//a[contains(@href,'com')][2]/@href像这样使用 get() ：
response.xpath('//a[contains(@href,'com')][2]/@href').get()
