CODEWITHSUNDEEP
ruby-on-railsdelayed-job
danneu
danneu

Reputation: 9444

How do you delete a delayed_job within the job's class?

(Using collectiveidea's delayed_job)

I have a job that scrapes for a keyword, but I want the job to destroy itself if the keyword has since been deleted since it was enqueued (i.e. a user deletes one of his keywords).

class ScrapingJob < Struct.new(:keyword_id)
  def perform
      keyword = Keyword.find(keyword_id)
      data = keyword.scrape
      keyword.details.create!(:text => data[:text])
  end
end

I was trying to put it in DJ's before hook by moving the keyword lookup into something like:

def before(job)
    # If keyword doesn't exist, destroy job
    begin
        @keyword = Keyword.find(keyword_id)
    rescue 'RecordNotFound'
        self.destroy
    end
end

The job fails, so DJ keeps re-attempting this job until it hits whatever retry cap I have specified.

Here's the failure:

Keyword Load (0.4ms)  SELECT "keywords".* FROM "keywords" 
    WHERE ("keywords"."id" = 292929) LIMIT 1
AREL (1.1ms)  UPDATE "delayed_jobs" 
    SET "last_error" = '{Couldn''t find Keyword with ID=292929
    ...
    ...

I want DJ to just destroy the job as soon as it sees that the keyword doesn't exist, bypassing the whole retry system.

Upvotes: 1

Views: 1554

Answers (2)

Daniel Morrison
Daniel Morrison

Reputation: 46

Just have it silently fail without an exception and the job will be gone.

  def perform
    if keyword = Keyword.find_by_id(keyword_id)
      data = keyword.scrape
      keyword.details.create!(:text => data[:text])
    end
  end

I changed find() to find_by_id() so it won't raise an exception but alternatively you could rescue.

This way, the job just doesn't do anything if the keyword is gone. A job that doesn't raise an exception just goes away.

We use this pattern quite a bit at Collective Idea.

Upvotes: 3

Denis Hennessy
Denis Hennessy

Reputation: 7473

Here's an easy solution by avoiding the exception:

class ScrapingJob < Struct.new(:keyword_id)
  def perform
      keyword = Keyword.find_by_id(keyword_id)
      unless keyword.nil?
          data = keyword.scrape
          keyword.details.create!(:text => data[:text])
      end
   end
end

Upvotes: 1

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