[MRG+1] Implement FormRequest.from_response CSS support

docs/topics/request-response.rst

@@ -282,7 +282,7 @@ fields with form data from :class:`Response` objects.
     The :class:`FormRequest` objects support the following class method in
     addition to the standard :class:`Request` methods:
 
-    .. classmethod:: FormRequest.from_response(response, [formname=None, formnumber=0, formdata=None, formxpath=None, clickdata=None, dont_click=False, ...])
+    .. classmethod:: FormRequest.from_response(response, [formname=None, formnumber=0, formdata=None, formxpath=None, formcss=None, clickdata=None, dont_click=False, ...])
 
        Returns a new :class:`FormRequest` object with its form field values
        pre-populated with those found in the HTML ``<form>`` element contained
@@ -310,6 +310,9 @@ fields with form data from :class:`Response` objects.
        :param formxpath: if given, the first form that matches the xpath will be used.
        :type formxpath: string
 
+       :param formcss: if given, the first form that matches the css selector will be used.
+       :type formcss: string
+
        :param formnumber: the number of form to use, when the response contains
           multiple forms. The first one (and also the default) is ``0``.
        :type formnumber: integer
@@ -339,6 +342,9 @@ fields with form data from :class:`Response` objects.
        .. versionadded:: 0.17
           The ``formxpath`` parameter.
 
+       .. versionadded:: 1.1.5
+          The ``formcss`` parameter.
+
 Request usage examples
 ----------------------
 

scrapy/http/request/form.py

@@ -34,8 +34,14 @@ def __init__(self, *args, **kwargs):
 
     @classmethod
     def from_response(cls, response, formname=None, formid=None, formnumber=0, formdata=None,
-                      clickdata=None, dont_click=False, formxpath=None, **kwargs):
+                      clickdata=None, dont_click=False, formxpath=None, formcss=None, **kwargs):
+
         kwargs.setdefault('encoding', response.encoding)
+
+        if formcss is not None:
+            from parsel.csstranslator import HTMLTranslator
+            formxpath = HTMLTranslator().css_to_xpath(formcss)
+
         form = _get_form(response, formname, formid, formnumber, formxpath)
         formdata = _get_inputs(form, formdata, dont_click, clickdata, response)
         url = _get_form_url(form, kwargs.pop('url', None))
@@ -73,7 +79,7 @@ def _get_form(response, formname, formid, formnumber, formxpath):
         f = root.xpath('//form[@id="%s"]' % formid)
         if f:
             return f[0]
-            
+
     # Get form element from xpath, if not found, go up
     if formxpath is not None:
         nodes = root.xpath(formxpath)

tests/test_http_request.py

@@ -846,6 +846,26 @@ def test_html_base_form_action(self):
         req = self.request_class.from_response(response)
         self.assertEqual(req.url, 'http://b.com/test_form')
 
+    def test_from_response_css(self):
+        response = _buildresponse(
+            """<form action="post.php" method="POST">
+            <input type="hidden" name="one" value="1">
+            <input type="hidden" name="two" value="2">
+            </form>
+            <form action="post2.php" method="POST">
+            <input type="hidden" name="three" value="3">
+            <input type="hidden" name="four" value="4">
+            </form>""")
+        r1 = self.request_class.from_response(response, formcss="form[action='post.php']")
+        fs = _qs(r1)
+        self.assertEqual(fs[b'one'], [b'1'])
+
+        r1 = self.request_class.from_response(response, formcss="input[name='four']")
+        fs = _qs(r1)
+        self.assertEqual(fs[b'three'], [b'3'])
+
+        self.assertRaises(ValueError, self.request_class.from_response,
+                          response, formcss="input[name='abc']")
 
 def _buildresponse(body, **kwargs):
     kwargs.setdefault('body', body)