python - Scrapy: overwrite DEPTH_LIMIT variable based on value read from custom config -

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i using initspider , read custom json configuration within def __init__(self, *a, **kw): method.

the json config file contains directive can control crawling depth. can read configuration file , extract value. main problem how tell scrapy use value.

note: dont want use command line argument such -s depth_limit=3, want parse custom configuration.

depth_limit used in scrapy.spidermiddlewares.depth.depthmiddleware. might have had quick @ code, you'll see depth_limit value read when initializing middleware.

i think might solution you:

  1. in __init__ method of spider, set spider attribute max_depth custom value.
  2. override scrapy.spidermiddlewares.depth.depthmiddleware , have check max_depth attribute.
  3. disable default depthmiddleware , enable own 1 in settings.

see http://doc.scrapy.org/en/latest/topics/spider-middleware.html

a quick example of overridden middleware described in step #2:

class mydepthmiddleware(depthmiddleware):      def process_spider_output(self, response, result, spider):     if hasattr(spider, 'max_depth'):         self.maxdepth = getattr(spider, 'max_depth')     return super(mydepthmiddleware, self).process_spider_output(response, result, spider)

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