Difference in FormRequest Post action in python 3 against python2

Posted almost 7 years ago by watch

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Un Answered

watch

Hi Team,

Below FormRequest post action is working fine in python 2 for scrapy:1.5 but now working in scrapy:1.5-py3. Having callback_method information in meta dict is causing failure. Please highlight or suggest work around.

yield FormRequest(url=login_url, callback=self.after_login, formdata=form_data
        ,meta={'followup_url':url,'callback_method':callback_method})

Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/scrapy/utils/defer.py", line 102, in iter_errback
    yield next(it)
GeneratorExit

Unhandled error in Deferred:

[twisted] Unhandled error in Deferred:

Traceback (most recent call last): Less

     File "/usr/local/lib/python3.6/site-packages/twisted/internet/base.py", line 1243, in run
       self.mainLoop()
     File "/usr/local/lib/python3.6/site-packages/twisted/internet/base.py", line 1252, in mainLoop
       self.runUntilCurrent()
     File "/usr/local/lib/python3.6/site-packages/twisted/internet/base.py", line 878, in runUntilCurrent
       call.func(*call.args, **call.kw)
     File "/usr/local/lib/python3.6/site-packages/twisted/internet/task.py", line 671, in _tick
       taskObj._oneWorkUnit()
   --- <exception caught here> ---
     File "/usr/local/lib/python3.6/site-packages/twisted/internet/task.py", line 517, in _oneWorkUnit
       result = next(self._iterator)
     File "/usr/local/lib/python3.6/site-packages/scrapy/utils/defer.py", line 63, in <genexpr>
       work = (callable(elem, *args, **named) for elem in iterable)
     File "/usr/local/lib/python3.6/site-packages/scrapy/core/scraper.py", line 183, in _process_spidermw_output
       self.crawler.engine.crawl(request=output, spider=spider)
     File "/usr/local/lib/python3.6/site-packages/scrapy/core/engine.py", line 210, in crawl
       self.schedule(request, spider)
     File "/usr/local/lib/python3.6/site-packages/scrapy/core/engine.py", line 216, in schedule
       if not self.slot.scheduler.enqueue_request(request):
     File "/usr/local/lib/python3.6/site-packages/scrapy/core/scheduler.py", line 57, in enqueue_request
       dqok = self._dqpush(request)
     File "/usr/local/lib/python3.6/site-packages/scrapy/core/scheduler.py", line 86, in _dqpush
       self.dqs.push(reqd, -request.priority)
     File "/usr/local/lib/python3.6/site-packages/queuelib/pqueue.py", line 35, in push
       q.push(obj) # this may fail (eg. serialization error)
     File "/usr/local/lib/python3.6/site-packages/scrapy/squeues.py", line 15, in push
       s = serialize(obj)
     File "/usr/local/lib/python3.6/site-packages/scrapy/squeues.py", line 27, in _pickle_serialize
       return pickle.dumps(obj, protocol=2)
   builtins.TypeError: can't pickle _thread.lock objects
   
   
[twisted] Less

Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/twisted/internet/task.py", line 517, in _oneWorkUnit
    result = next(self._iterator)
  File "/usr/local/lib/python3.6/site-packages/scrapy/utils/defer.py", line 63, in <genexpr>
    work = (callable(elem, *args, **named) for elem in iterable)
  File "/usr/local/lib/python3.6/site-packages/scrapy/core/scraper.py", line 183, in _process_spidermw_output
    self.crawler.engine.crawl(request=output, spider=spider)
  File "/usr/local/lib/python3.6/site-packages/scrapy/core/engine.py", line 210, in crawl
    self.schedule(request, spider)
  File "/usr/local/lib/python3.6/site-packages/scrapy/core/engine.py", line 216, in schedule
    if not self.slot.scheduler.enqueue_request(request):
  File "/usr/local/lib/python3.6/site-packages/scrapy/core/scheduler.py", line 57, in enqueue_request
    dqok = self._dqpush(request)
  File "/usr/local/lib/python3.6/site-packages/scrapy/core/scheduler.py", line 86, in _dqpush
    self.dqs.push(reqd, -request.priority)
  File "/usr/local/lib/python3.6/site-packages/queuelib/pqueue.py", line 35, in push
    q.push(obj) # this may fail (eg. serialization error)
  File "/usr/local/lib/python3.6/site-packages/scrapy/squeues.py", line 15, in push
    s = serialize(obj)
  File "/usr/local/lib/python3.6/site-packages/scrapy/squeues.py", line 27, in _pickle_serialize
    return pickle.dumps(obj, protocol=2)
TypeError: can't pickle _thread.lock objects

0 Votes

2 Comments

watch posted almost 7 years ago

Please note that above statement is working fine in local environment for python 3.6. Issue only when running via scrapinghub

0 Votes

watch posted almost 7 years ago

Hi Team,

Was able to make it work in scrapy:1.5-py3 using getattr()

response.meta['callback_url'] = response.url
response.meta['callback_method'] = callback_method.__name__
yield FormRequest(url=login_url, callback=self.after_login, formdata=form_data, meta=response.meta)

def after_login(self, response):
    yield response.follow(url=response.meta['callback_url'], callback=getattr(self,response.meta['callback_method']),
                      meta=response.meta)

Explanation on why earlier code failed when passing function via FormRequest meta under scrapy:1.5-py3 would be helpful

0 Votes