The irregular events are referred to as exceptions. In Scrapy, exceptions are raised due to reasons such as missing configuration, dropping item from the item pipeline, etc. Following is the list of exceptions mentioned in Scrapy and their application.
Item Pipeline utilizes this exception to stop processing of the item at any stage. It can be written as −
exception (scrapy.exceptions.DropItem)
This exception is used to stop the spider using the callback request. It can be written as −
exception (scrapy.exceptions.CloseSpider)(reason = 'cancelled')
It contains parameter called reason (str) which specifies the reason for closing.
For instance, the following code shows this exception usage −
def parse_page(self, response): if 'Bandwidth exceeded' in response.body: raise CloseSpider('bandwidth_exceeded')
This exception is used by scheduler or downloader middleware to ignore a request. It can be written as −
exception (scrapy.exceptions.IgnoreRequest)
It indicates a missing configuration situation and should be raised in a component constructor.
exception (scrapy.exceptions.NotConfigured)
This exception can be raised, if any of the following components are disabled.
This exception is raised when any feature or method is not supported. It can be written as −
exception (scrapy.exceptions.NotSupported)