Fix max_length issue for mysql

README.rst

@@ -269,6 +269,17 @@ pip command::
 
     $ pip install https://github.com/celery/django-celery-beat/zipball/master#egg=django-celery-beat
 
+Issues with mysql
+-----------------
+ If you want to run ``django-celery-beat`` with MySQL, you might run into some issues.
+
+ One such issue is when you try to run ``python manage.py migrate django_celery_beat``, you might get the following error::
+     django.db.utils.OperationalError: (1071, 'Specified key was too long; max key length is 767 bytes')
+ To get around this issue, you can set::
+     DJANGO_CELERY_BEAT_NAME_MAX_LENGTH=191
+ (or any other value if any other db other than MySQL is causing similar issues.)
+ max_length of **191** seems to work for MySQL.
+
 
 TZ Awareness:
 -------------

django_celery_beat/migrations/0001_initial.py

@@ -4,6 +4,7 @@
 
 from django.db import migrations, models
 import django.db.models.deletion
+from django.conf import settings
 
 
 class Migration(migrations.Migration):
@@ -71,8 +72,15 @@ class Migration(migrations.Migration):
                     auto_created=True, primary_key=True,
                     serialize=False, verbose_name='ID')),
                 ('name', models.CharField(
-                    help_text='Useful description', max_length=200,
-                    unique=True, verbose_name='name')),
+                    help_text='Useful description',
+                    max_length=getattr(
+                        settings,
+                        'DJANGO_CELERY_BEAT_NAME_MAX_LENGTH',
+                        200
+                    ),
+                    unique=True,
+                    verbose_name='name'
+                )),
                 ('task', models.CharField(
                     max_length=200, verbose_name='task name')),
                 ('args', models.TextField(

django_celery_beat/models.py

@@ -317,7 +317,12 @@ class PeriodicTask(models.Model):
     """Model representing a periodic task."""
 
     name = models.CharField(
-        max_length=200, unique=True,
+        max_length=getattr(
+            settings,
+            'DJANGO_CELERY_BEAT_NAME_MAX_LENGTH',
+            200
+        ),
+        unique=True,
         verbose_name=_('Name'),
         help_text=_('Short Description For This Task'),
     )

t/unit/test_models.py

@@ -1,14 +1,52 @@
 from __future__ import absolute_import, unicode_literals
+import importlib
 import os
 
-from django.test import TestCase
 from django.apps import apps
-from django.db.migrations.state import ProjectState
 from django.db.migrations.autodetector import MigrationAutodetector
 from django.db.migrations.loader import MigrationLoader
 from django.db.migrations.questioner import NonInteractiveMigrationQuestioner
+from django.db.migrations.state import ProjectState
+from django.test import TestCase, override_settings
+from django.utils import six
+
+from django_celery_beat import migrations as beat_migrations, models
+
+
+class ModelMigrationTests(TestCase):
+    def test_periodic_task_name_max_length_defaults_to_200_in_model(self):
+        six.moves.reload_module(models)
+        self.assertEqual(
+            200, models.PeriodicTask._meta.get_field('name').max_length)
+
+    @override_settings(DJANGO_CELERY_BEAT_NAME_MAX_LENGTH=191)
+    def test_periodic_task_name_max_length_changed_to_191_in_model(self):
+        six.moves.reload_module(models)
+        self.assertEqual(
+            191, models.PeriodicTask._meta.get_field('name').max_length)
+
+    def test_periodic_task_name_max_length_defaults_to_200_in_migration(self):
+        initial_migration_module = importlib.import_module(
+            'django_celery_beat.migrations.0001_initial')
+        six.moves.reload_module(initial_migration_module)
+        initial_migration = initial_migration_module.Migration
+        periodic_task_creation = initial_migration.operations[2]
+        fields = dict(periodic_task_creation.fields)
+
+        self.assertEqual('PeriodicTask', periodic_task_creation.name)
+        self.assertEqual(200, fields['name'].max_length)
+
+    @override_settings(DJANGO_CELERY_BEAT_NAME_MAX_LENGTH=191)
+    def test_periodic_task_name_max_length_changed_to_191_in_migration(self):
+        initial_migration_module = importlib.import_module(
+            'django_celery_beat.migrations.0001_initial')
+        six.moves.reload_module(initial_migration_module)
+        initial_migration = initial_migration_module.Migration
+        periodic_task_creation = initial_migration.operations[2]
+        fields = dict(periodic_task_creation.fields)
 
-from django_celery_beat import migrations as beat_migrations
+        self.assertEqual('PeriodicTask', periodic_task_creation.name)
+        self.assertEqual(191, fields['name'].max_length)
 
 
 class MigrationTests(TestCase):

tox.ini

@@ -41,7 +41,8 @@ sitepackages = False
 recreate = False
 commands =
     pip list
-    py.test -xv
+    py.test -xv --ignore=t/unit/test_models.py
+    py.test -xv -k 'ModelMigrationTests'
 
 [testenv:upgradebeat111]
 basepython = python2.7
@@ -170,4 +171,4 @@ commands =
     pip install -U https://github.com/celery/celery/zipball/master#egg=celery
     pip install -U https://github.com/celery/kombu/zipball/master#egg=kombu
     pip install Django==2.0
-    py.test -x --cov=django_celery_beat --cov-report=xml --no-cov-on-fail
+    py.test -x --cov=django_celery_beat --cov-report=xml --no-cov-on-fail --ignore=t/unit/test_models.py