Handling errbacks #158
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Handling errbacks #158
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The errback should never have been defaulted to the 'parse' method of the spider. By doing this it invalidates what the scrapy docs say. Also, there is no documentation on the scrapy site that says that exceptions get sent to the parse method. The reason this was found is because the error handling in the `process_spider_exception` middleware was never getting called as the scrapy docs said it should be. The workaround to get it to work the way it did before with the 'parse' method is add `&errback=parse` in the request.
This will allow the ability to change the non-standard behavior of sending exceptions to the `parse` method of the spider without introducing a breaking change to scrapyrt. It also introduces some documentation of the existing behavior.
Currently the application is not reporting to the user when the user provides an invalid errback or callback method. The scheduling of the request and validation of the spider callback and errback happens in a different thread than the one which is handling the api request. So, we need a different mechanism to communicate with the api request thread than simply raising the exception. We already do this for other errors and responses by adding properties to the CrawlManager object. So it seems best to also communicate this exception to the api request by using a user_error property on the CrawlManager. Then the exception can be raised in the context of the api request.
Co-authored-by: Adrián Chaves <adrian@chaves.io>
Co-authored-by: Adrián Chaves <adrian@chaves.io>
Gallaecio
approved these changes
Feb 14, 2024
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