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import re
import datetime
import decimal
import json
from twisted.internet import defer
from scrapy.spider import Spider
from scrapy.http import Request, Response
from scrapy.item import BaseItem
class SpiderReferencer(object):
"""Class to serialize (and deserialize) objects (typically dicts)
containing references to running spiders (ie. Spider objects). This is
required because json library fails to serialize dicts containing
non-primitive types as keys, even when you override
ScrapyJSONEncoder.default() with a custom encoding mechanism.
"""
spider_ref_re = re.compile('^spider:([0-9a-f]+)?:?(.+)?$')
def __init__(self, crawler):
self.crawler = crawler
def get_reference_from_spider(self, spider):
return 'spider:%x:%s' % (id(spider), spider.name)
def get_spider_from_reference(self, ref):
"""Returns the Spider referenced by text, if text is a spider
reference. Otherwise it returns the text itself. If the text references
a non-running spider it raises a RuntimeError.
"""
m = self.spider_ref_re.search(ref)
if m:
spid, spname = m.groups()
for spider in self.crawler.engine.open_spiders:
if "%x" % id(spider) == spid or spider.name == spname:
return spider
raise RuntimeError("Spider not running: %s" % ref)
return ref
def encode_references(self, obj):
"""Look for Spider objects and replace them with spider references"""
if isinstance(obj, Spider):
return self.get_reference_from_spider(obj)
elif isinstance(obj, dict):
d = {}
for k, v in obj.items():
k = self.encode_references(k)
v = self.encode_references(v)
d[k] = v
return d
elif isinstance(obj, (list, tuple)):
return [self.encode_references(x) for x in obj]
else:
return obj
def decode_references(self, obj):
"""Look for spider references and replace them with Spider objects"""
if isinstance(obj, basestring):
return self.get_spider_from_reference(obj)
elif isinstance(obj, dict):
d = {}
for k, v in obj.items():
k = self.decode_references(k)
v = self.decode_references(v)
d[k] = v
return d
elif isinstance(obj, (list, tuple)):
return [self.decode_references(x) for x in obj]
else:
return obj
class ScrapyJSONEncoder(json.JSONEncoder):
DATE_FORMAT = "%Y-%m-%d"
TIME_FORMAT = "%H:%M:%S"
def __init__(self, *a, **kw):
crawler = kw.pop('crawler', None)
self.spref = kw.pop('spref', None) or SpiderReferencer(crawler)
super(ScrapyJSONEncoder, self).__init__(*a, **kw)
def encode(self, o):
if self.spref:
o = self.spref.encode_references(o)
return super(ScrapyJSONEncoder, self).encode(o)
def default(self, o):
if isinstance(o, datetime.datetime):
return o.strftime("%s %s" % (self.DATE_FORMAT, self.TIME_FORMAT))
elif isinstance(o, datetime.date):
return o.strftime(self.DATE_FORMAT)
elif isinstance(o, datetime.time):
return o.strftime(self.TIME_FORMAT)
elif isinstance(o, decimal.Decimal):
return str(o)
elif isinstance(o, defer.Deferred):
return str(o)
elif isinstance(o, BaseItem):
return dict(o)
elif isinstance(o, Request):
return "<%s %s %s>" % (type(o).__name__, o.method, o.url)
elif isinstance(o, Response):
return "<%s %s %s>" % (type(o).__name__, o.status, o.url)
else:
return super(ScrapyJSONEncoder, self).default(o)
class ScrapyJSONDecoder(json.JSONDecoder):
def __init__(self, *a, **kw):
crawler = kw.pop('crawler', None)
self.spref = kw.pop('spref', None) or SpiderReferencer(crawler)
super(ScrapyJSONDecoder, self).__init__(*a, **kw)
def decode(self, s):
o = super(ScrapyJSONDecoder, self).decode(s)
if self.spref:
o = self.spref.decode_references(o)
return o
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