Fix info sharing between req and download mw with Request.meta

The canonical way to share info between `Request` and download middleware is
`Request.meta`. Custom attributes `Request.custom_attr` should be avoided,
cause they may be dropped after possible serialization and de-serialization
in `Scheduler`.

E.g. `scrapy-redis` converts `Request` into dict with
`scrapy.utils.reqpar.request_to_dict()`.
Custom attribute on `Request` will be lost.

Author: laggardkernel

scrapy_selenium/http.py

@@ -24,9 +24,12 @@ def __init__(self, wait_time=None, wait_until=None, screenshot=False, script=Non
 
         """
 
-        self.wait_time = wait_time
-        self.wait_until = wait_until
-        self.screenshot = screenshot
-        self.script = script
-
+        meta = {
+            "wait_time": wait_time,
+            "wait_until": wait_until,
+            "screenshot": screenshot,
+            "script": script,
+        }
+        meta.update(kwargs.pop("meta", {}))
+        kwargs["meta"] = meta
         super().__init__(*args, **kwargs)

scrapy_selenium/middlewares.py

@@ -110,16 +110,16 @@ def process_request(self, request, spider):
                 }
             )
 
-        if request.wait_until:
-            WebDriverWait(self.driver, request.wait_time).until(
-                request.wait_until
+        if request.meta.get('wait_until'):
+            WebDriverWait(self.driver, request.meta.get('wait_time')).until(
+                request.meta.get('wait_until')
             )
 
-        if request.screenshot:
+        if request.meta.get('screenshot'):
             request.meta['screenshot'] = self.driver.get_screenshot_as_png()
 
-        if request.script:
-            self.driver.execute_script(request.script)
+        if request.meta.get('script'):
+            self.driver.execute_script(request.meta.get('script'))
 
         body = str.encode(self.driver.page_source)