Add django constance to thirdpart to void dependency

thirdpart/constance/backends/database/__init__.py

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+from django.core.exceptions import ImproperlyConfigured
+from django.db.models.signals import post_save
+from django.core.cache import get_cache
+
+try:
+    from django.core.cache.backends.locmem import LocMemCache
+except ImportError:
+    from django.core.cache.backends.locmem import CacheClass as LocMemCache
+
+from .. import Backend
+from ... import settings
+
+
+class DatabaseBackend(Backend):
+    def __init__(self):
+        from .models import Constance
+        self._model = Constance
+        self._prefix = settings.DATABASE_PREFIX
+        self._autofill_timeout = settings.DATABASE_CACHE_AUTOFILL_TIMEOUT
+        self._autofill_cachekey = 'autofilled'
+
+        if not self._model._meta.installed:
+            raise ImproperlyConfigured(
+                "The constance.backends.database app isn't installed "
+                "correctly. Make sure it's in your INSTALLED_APPS setting.")
+
+        if settings.DATABASE_CACHE_BACKEND:
+            self._cache = get_cache(settings.DATABASE_CACHE_BACKEND)
+            if isinstance(self._cache, LocMemCache):
+                raise ImproperlyConfigured(
+                    "The CONSTANCE_DATABASE_CACHE_BACKEND setting refers to a "
+                    "subclass of Django's local-memory backend (%r). Please set "
+                    "it to a backend that supports cross-process caching."
+                    % settings.DATABASE_CACHE_BACKEND)
+        else:
+            self._cache = None
+        self.autofill()
+        # Clear simple cache.
+        post_save.connect(self.clear, sender=self._model)
+
+    def add_prefix(self, key):
+        return "%s%s" % (self._prefix, key)
+
+    def autofill(self):
+        if not self._autofill_timeout or not self._cache:
+            return
+        full_cachekey = self.add_prefix(self._autofill_cachekey)
+        if self._cache.get(full_cachekey):
+            return
+        autofill_values = {}
+        autofill_values[full_cachekey] = 1
+        for key, value in self.mget(settings.CONFIG.keys()):
+            autofill_values[self.add_prefix(key)] = value
+        self._cache.set_many(autofill_values, timeout=self._autofill_timeout)
+
+    def mget(self, keys):
+        if not keys:
+            return
+        keys = dict((self.add_prefix(key), key) for key in keys)
+        stored = self._model._default_manager.filter(key__in=keys.keys())
+        for const in stored:
+            yield keys[const.key], const.value
+
+    def get(self, key):
+        key = self.add_prefix(key)
+        if self._cache:
+            value = self._cache.get(key)
+        else:
+            value = None
+        if value is None:
+            try:
+                value = self._model._default_manager.get(key=key).value
+            except self._model.DoesNotExist:
+                pass
+            else:
+                if self._cache:
+                    self._cache.add(key, value)
+        return value
+
+    def set(self, key, value):
+        constance, created = self._model._default_manager.get_or_create(
+            key=self.add_prefix(key), defaults={'value': value}
+        )
+        if not created:
+            constance.value = value
+            constance.save()
+
+    def clear(self, sender, instance, created, **kwargs):
+        if self._cache and not created:
+            keys = [self.add_prefix(k)
+                    for k in settings.CONFIG.keys()]
+            keys.append(self.add_prefix(self._autofill_cachekey))
+            self._cache.delete_many(keys)
+            self.autofill()

thirdpart/constance/backends/database/migrations/0001_initial.py

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+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import models, migrations
+import picklefield.fields
+
+
+class Migration(migrations.Migration):
+    dependencies = []
+
+    operations = [
+        migrations.CreateModel(
+            name='Constance',
+            fields=[
+                ('id', models.AutoField(verbose_name='ID', primary_key=True,
+                                        auto_created=True, serialize=False)),
+                ('key', models.CharField(unique=True, max_length=255)),
+                ('value', picklefield.fields.PickledObjectField(editable=False)),
+            ],
+            options={
+                'verbose_name': 'constance',
+                'verbose_name_plural': 'constances',
+                'db_table': 'constance_config',
+            },
+            bases=(models.Model,),
+        ),
+    ]

thirdpart/constance/backends/database/models.py

@@ -0,0 +1,24 @@
+from django.db import models
+from django.core.exceptions import ImproperlyConfigured
+
+from django.utils.translation import ugettext_lazy as _
+
+try:
+    from picklefield import PickledObjectField
+except ImportError:
+    raise ImproperlyConfigured("Couldn't find the the 3rd party app "
+                               "django-picklefield which is required for "
+                               "the constance database backend.")
+
+
+class Constance(models.Model):
+    key = models.CharField(max_length=255, unique=True)
+    value = PickledObjectField()
+
+    class Meta:
+        verbose_name = _('constance')
+        verbose_name_plural = _('constances')
+        db_table = 'constance_config'
+
+    def __unicode__(self):
+        return self.key

thirdpart/constance/backends/database/south_migrations/0001_initial.py

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+# -*- coding: utf-8 -*-
+from south.db import db
+from south.v2 import SchemaMigration
+
+
+class Migration(SchemaMigration):
+
+    def forwards(self, orm):
+        # Adding model 'Constance'
+        db.create_table('constance_config', (
+            ('id', self.gf('django.db.models.fields.AutoField')(
+                primary_key=True)),
+            ('key', self.gf('django.db.models.fields.TextField')()),
+            ('value', self.gf('picklefield.fields.PickledObjectField')()),
+        ))
+        db.send_create_signal('database', ['Constance'])
+
+    def backwards(self, orm):
+        # Deleting model 'Constance'
+        db.delete_table('constance_config')
+
+    models = {
+        'database.constance': {
+            'Meta': {'object_name': 'Constance',
+                     'db_table': "'constance_config'"},
+            'id': ('django.db.models.fields.AutoField', [],
+                   {'primary_key': 'True'}),
+            'key': ('django.db.models.fields.TextField', [], {}),
+            'value': ('picklefield.fields.PickledObjectField', [], {})
+        }
+    }
+
+    complete_apps = ['database']

thirdpart/constance/backends/database/south_migrations/0002_auto__chg_field_constance_key__add_unique_constance_key.py

@@ -0,0 +1,36 @@
+# -*- coding: utf-8 -*-
+from south.db import db
+from south.v2 import SchemaMigration
+
+
+class Migration(SchemaMigration):
+
+    def forwards(self, orm):
+        # Changing field 'Constance.key'
+        db.alter_column('constance_config', 'key',
+                        self.gf('django.db.models.fields.CharField')(
+                            max_length=255))
+        # Adding unique constraint on 'Constance', fields ['key']
+        db.create_unique('constance_config', ['key'])
+
+    def backwards(self, orm):
+        # Removing unique constraint on 'Constance', fields ['key']
+        db.delete_unique('constance_config', ['key'])
+
+        # Changing field 'Constance.key'
+        db.alter_column('constance_config', 'key',
+                        self.gf('django.db.models.fields.TextField')())
+
+    models = {
+        'database.constance': {
+            'Meta': {'object_name': 'Constance',
+                     'db_table': "'constance_config'"},
+            'id': ('django.db.models.fields.AutoField', [],
+                   {'primary_key': 'True'}),
+            'key': ('django.db.models.fields.CharField', [],
+                    {'unique': 'True', 'max_length': '255'}),
+            'value': ('picklefield.fields.PickledObjectField', [], {})
+        }
+    }
+
+    complete_apps = ['database']