问题
I'm trying to extract (what appears to be) JSON data from within an HTML script. The HTML script looks like this on the site:
<script>
$(document).ready(function(){
var terms = new Verba.Compare.Collections.Terms([{"id":"6436","name":"SUMMER 16","inquiry":true,"ordering":true},{"id":"6517","name":"FALL 16","inquiry":true,"ordering":true}]);
var view = new Verba.Compare.Views.CourseSelector({el: "body", terms: terms});
});
</script>
I'd like to pull out the following:
[{"id":"6436","name":"SUMMER 16","inquiry":true,"ordering":true},{"id":"6517","name":"FALL 16","inquiry":true,"ordering":true}]
Using the following code, I'm able to get the full script.
def parse(self, response):
print response.xpath('/html/body/script[2]').extract()
Is there a simple way to then extract the values for "id", "name", etc. from that script. Or, is there a more direct way by modifying the xpath? I can't seem to go any deeper on the xpath using firebug.
回答1:
You can use js2xml for this.
To illustrate, first, let's create a Scrapy selector with your sample HTML, and grab the JavaScript statements:
>>> import scrapy
>>> sample = '''<script>
... $(document).ready(function(){
... var terms = new Verba.Compare.Collections.Terms([{"id":"6436","name":"SUMMER 16","inquiry":true,"ordering":true},{"id":"6517","name":"FALL 16","inquiry":true,"ordering":true}]);
... var view = new Verba.Compare.Views.CourseSelector({el: "body", terms: terms});
... });
... </script>'''
>>> selector = scrapy.Selector(text=sample, type='html')
>>> selector.xpath('//script//text()').extract_first()
u'\n $(document).ready(function(){\n var terms = new Verba.Compare.Collections.Terms([{"id":"6436","name":"SUMMER 16","inquiry":true,"ordering":true},{"id":"6517","name":"FALL 16","inquiry":true,"ordering":true}]);\n var view = new Verba.Compare.Views.CourseSelector({el: "body", terms: terms});\n });\n'
Then we can parse the JavaScript code with js2xml. You get an lxml tree back:
>>> import js2xml
>>> jssnippet = selector.xpath('//script//text()').extract_first()
>>> jstree = js2xml.parse(jssnippet)
>>> jstree
<Element program at 0x7fc7c6bae1b8>
What does the tree look like? It's pretty verbose:
>>> print(js2xml.pretty_print(jstree))
<program>
<functioncall>
<function>
<dotaccessor>
<object>
<functioncall>
<function>
<identifier name="$"/>
</function>
<arguments>
<identifier name="document"/>
</arguments>
</functioncall>
</object>
<property>
<identifier name="ready"/>
</property>
</dotaccessor>
</function>
<arguments>
<funcexpr>
<identifier/>
<parameters/>
<body>
<var name="terms">
<new>
<dotaccessor>
<object>
<dotaccessor>
<object>
<dotaccessor>
<object>
<identifier name="Verba"/>
</object>
<property>
<identifier name="Compare"/>
</property>
</dotaccessor>
</object>
<property>
<identifier name="Collections"/>
</property>
</dotaccessor>
</object>
<property>
<identifier name="Terms"/>
</property>
</dotaccessor>
<arguments>
<array>
<object>
<property name="id">
<string>6436</string>
</property>
<property name="name">
<string>SUMMER 16</string>
</property>
<property name="inquiry">
<boolean>true</boolean>
</property>
<property name="ordering">
<boolean>true</boolean>
</property>
</object>
<object>
<property name="id">
<string>6517</string>
</property>
<property name="name">
<string>FALL 16</string>
</property>
<property name="inquiry">
<boolean>true</boolean>
</property>
<property name="ordering">
<boolean>true</boolean>
</property>
</object>
</array>
</arguments>
</new>
</var>
<var name="view">
<new>
<dotaccessor>
<object>
<dotaccessor>
<object>
<dotaccessor>
<object>
<identifier name="Verba"/>
</object>
<property>
<identifier name="Compare"/>
</property>
</dotaccessor>
</object>
<property>
<identifier name="Views"/>
</property>
</dotaccessor>
</object>
<property>
<identifier name="CourseSelector"/>
</property>
</dotaccessor>
<arguments>
<object>
<property name="el">
<string>body</string>
</property>
<property name="terms">
<identifier name="terms"/>
</property>
</object>
</arguments>
</new>
</var>
</body>
</funcexpr>
</arguments>
</functioncall>
</program>
You can use your XPath skills to point to the JavaScript array (you want the 1st argument of the "dot" accessor for the new contruct assigned to var terms):
>>> jstree.xpath('//var[@name="terms"]')
[<Element var at 0x7fc7c565e638>]
>>> jstree.xpath('//var[@name="terms"]/new/arguments/*')
[<Element array at 0x7fc7c565e5a8>]
>>> jstree.xpath('//var[@name="terms"]/new/arguments/*')[0]
<Element array at 0x7fc7c565e5a8>
Finally, now that you have the <array> element, you can pass it to js2xml.jsonlike.make_dict() to get a nice Python object to work with (make_dict is kinda misnamed):
>>> js2xml.jsonlike.make_dict(jstree.xpath('//var[@name="terms"]/new/arguments/*')[0])
[{'ordering': True, 'inquiry': True, 'id': '6436', 'name': 'SUMMER 16'}, {'ordering': True, 'inquiry': True, 'id': '6517', 'name': 'FALL 16'}]
>>>
Note: you can also use the shortcut js2xml.jsonlike.getall() to fetch everything that looks like a Python dict or list (you get 2 lists, you're interested in the 1st one):
>>> js2xml.jsonlike.getall(jstree)
[[{'ordering': True, 'inquiry': True, 'id': '6436', 'name': 'SUMMER 16'}, {'ordering': True, 'inquiry': True, 'id': '6517', 'name': 'FALL 16'}], {'el': 'body', 'terms': 'terms'}]
回答2:
I would extract it using a regex, something like:
response.xpath('/html/body/script[2]').re_first('\((\[.*\])\)')
回答3:
chompjs provides an API to parse JavaScript objects into a dict.
For example, if the JavaScript code contains var data = {field: "value", secondField: "second value"}; you can extract that data as follows:
import chompjs
javascript = response.css('script::text').get()
data = chompjs.parse_js_object(javascript)
The final result is
{'field': 'value', 'secondField': 'second value'}
a
回答4:
You can't go "deeper" because that element's contents are just text. It's not too hard to read out the JSON from the JavaScript:
line = javascript.strip().splitlines()[1]
the_json = line.split('(', 1)[1].split(')', 1)[0]
来源：https://stackoverflow.com/questions/38470261/scrapy-extract-json-from-within-html-script