Fix issue #15

Added exception catching in float(job_execution.finished) to prevent float(None)
Added tests for such situation
Now next_run_time allowed to be blank and null. Added migration for it

django_apscheduler/migrations/0002_auto_20180412_0758.py

@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.12 on 2018-04-12 07:58
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('django_apscheduler', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='djangojob',
+            name='next_run_time',
+            field=models.DateTimeField(blank=True, db_index=True, null=True),
+        ),
+    ]

django_apscheduler/models.py

@@ -37,7 +37,7 @@ def __reconnect(self):
 
 class DjangoJob(models.Model):
     name = models.CharField(max_length=255, unique=True)  # id of job
-    next_run_time = models.DateTimeField(db_index=True)
+    next_run_time = models.DateTimeField(db_index=True, blank=True, null=True)
     # Perhaps consider using PickleField down the track.
     job_state = models.BinaryField()
 

django_apscheduler/result_storage.py

@@ -16,6 +16,7 @@ def get_or_create_job_execution(self, job, event):
         """
         Create and return new job execution item.
         :param job: DjangoJob instance
+        :type job: django_apscheduler.models.DjangoJob
         :param event: JobSubmissionEvent instance
         :return: JobExecution id
         """
@@ -29,7 +30,11 @@ def get_or_create_job_execution(self, job, event):
 
         if job_execution and job_execution.started is None:
             job_execution.started = time.time()
-            job_execution.duration = float(job_execution.finished) - float(job_execution.started)
+            try:
+                job_execution.duration = float(job_execution.finished) - float(job_execution.started)
+            except:
+                job_execution.duration = None
+
             job_execution.save()
             return job_execution.id
 

tests/test_jobstore.py

@@ -15,6 +15,8 @@
 
 from django_apscheduler.jobstores import DjangoJobStore, register_events, register_job
 from django_apscheduler.models import DjangoJob, DjangoJobExecution, DjangoJobManager
+from django_apscheduler.result_storage import DjangoResultStorage
+from django_apscheduler.util import serialize_dt
 from tests.compat import mock_compat
 
 logging.basicConfig()
@@ -106,7 +108,28 @@ def test_job_events(db, scheduler):
 
     assert DjangoJobExecution.objects.count() == 1
 
-@pytest.mark.test_reconnect_on_db_error
+
+def test_issue_15(db):
+    """
+    This test covers bug from https://github.com/jarekwg/django-apscheduler/issues/15
+    """
+
+    storage = DjangoResultStorage()
+
+    srt = datetime.datetime.now()
+
+    job = DjangoJob.objects.create(name="test", next_run_time=datetime.datetime.now())
+    DjangoJobExecution.objects.create(
+        job=job,
+        run_time=serialize_dt(srt)
+    )
+
+    storage.get_or_create_job_execution(
+        job,
+        mock_compat.Mock(scheduled_run_times=[srt])
+    )
+
+
 def test_reconnect_on_db_error(transactional_db):
 
     counter = [0]

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = {py36}-{dj1,dj2},{py27-dj1}
+envlist = {py36}-{dj1,dj2},{py27-dj1},{py35}-{dj1,dj2}
 skipsdist = true
 
 [pytest]