[#145] Throw + catch a custom exception if there are no jobs to run

If there are no harvesting jobs to run, there was always an ugly
exception message when using the paster command. This replaces the ugly
output with a proper message and uses a custom exception to allow others
to deal with this error differently.

ckanext/harvest/commands/harvester.py

@@ -3,6 +3,7 @@ from pprint import pprint
 
 from ckan import model
 from ckan.logic import get_action, ValidationError
+from ckanext.harvest.logic import NoNewHarvestJobError
 
 from ckan.lib.cli import CkanCommand
 
@@ -301,9 +302,10 @@ class Harvester(CkanCommand):
 
     def run_harvester(self):
         context = {'model': model, 'user': self.admin_user['name'], 'session':model.Session}
-        jobs = get_action('harvest_jobs_run')(context,{})
-
-        #print 'Sent %s jobs to the gather queue' % len(jobs)
+        try:
+            jobs = get_action('harvest_jobs_run')(context,{})
+        except NoNewHarvestJobError:
+            print 'There are no new harvest jobs to run.'
 
     def import_stage(self):
 

ckanext/harvest/logic/__init__.py

@@ -7,3 +7,7 @@ except ImportError:
 
 class HarvestJobExists(Exception):
     pass
+
+
+class NoNewHarvestJobError(Exception):
+    pass

ckanext/harvest/logic/action/update.py

@@ -26,7 +26,7 @@ from ckanext.harvest.plugin import DATASET_TYPE_NAME
 from ckanext.harvest.queue import get_gather_publisher, resubmit_jobs
 
 from ckanext.harvest.model import HarvestSource, HarvestJob, HarvestObject
-from ckanext.harvest.logic import HarvestJobExists
+from ckanext.harvest.logic import HarvestJobExists, NoNewHarvestJobError
 from ckanext.harvest.logic.schema import harvest_source_show_package_schema
 
 from ckanext.harvest.logic.action.get import harvest_source_show, harvest_job_list, _get_sources_for_user
@@ -365,7 +365,7 @@ def harvest_jobs_run(context,data_dict):
     jobs = harvest_job_list(context,{'source_id':source_id,'status':u'New'})
     if len(jobs) == 0:
         log.info('No new harvest jobs.')
-        raise Exception('There are no new harvesting jobs')
+        raise NoNewHarvestJobError('There are no new harvesting jobs')
 
     # Send each job to the gather queue
     publisher = get_gather_publisher()