mirror of
https://github.com/jazzband/django-dbtemplates.git
synced 2026-03-16 22:20:28 +00:00
Refactored template loader to use new backend architecture, that populates the cache by using signals.
Adds a BaseCacheBackend class with a simple API (load, save, remove) to be subclassed and specified in the DBTEMPLATES_CACHE_BACKEND settings. Adds DjangoCacheBackend (uses Django's own caching mechanism) and FileSystemBackend (simple approach to filesystem saving). git-svn-id: https://django-dbtemplates.googlecode.com/svn/trunk@58 cfb8ba98-e953-0410-9cff-959ffddf5974 committer: leidel <leidel@cfb8ba98-e953-0410-9cff-959ffddf5974> --HG-- extra : convert_revision : fde60d8ab2e834d898d9f662cf013d5546370eeb
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leidel
parent
391b00c655
commit
41ff350628
3 changed files with 170 additions and 67 deletions
97
dbtemplates/cache.py
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97
dbtemplates/cache.py
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@ -0,0 +1,97 @@
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import os
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from django.conf import settings
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from django.core.cache import cache
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from django.contrib.sites.models import Site
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from django.template import TemplateDoesNotExist
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from django.core.exceptions import ImproperlyConfigured
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from django.utils.encoding import smart_unicode, force_unicode
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class BaseCacheBackend(object):
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"""
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Base class for custom cache backend of dbtemplates to be used while
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subclassing.
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Set DBTEMPLATES_CACHE_BACKEND setting to the Python path to that subclass.
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"""
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def __init__(self):
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self.site = Site.objects.get_current()
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def load(self, name):
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"""
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Loads a template from the cache with the given name.
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"""
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raise NotImplemented
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def save(self, name, content):
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"""
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Saves the given template content with the given name in the cache.
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"""
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raise NotImplemented
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def remove(self, name):
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"""
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Removes the template with the given name from the cache.
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"""
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raise NotImplemented
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class DjangoCacheBackend(BaseCacheBackend):
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"""
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A cache backend that uses Django's cache mechanism.
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"""
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def _cache_key(self, name):
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return 'dbtemplates::%s' % name
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def load(self, name):
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cache_key = self._cache_key(name)
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return cache.get(cache_key)
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def save(self, name, content):
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cache_key = self._cache_key(name)
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cache.set(cache_key, content)
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def remove(self, name):
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cache_key = self._cache_key(name)
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cache.delete(cache_key)
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class FileSystemBackend(BaseCacheBackend):
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"""
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A cache backend that uses simple files to hold the template cache.
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"""
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def __init__(self):
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try:
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self.cache_dir = getattr(settings, 'DBTEMPLATES_CACHE_DIR', None)
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self.cache_dir = os.path.normpath(self.cache_dir)
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if not os.path.isdir(self.cache_dir):
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raise Exception
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except:
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raise ImproperlyConfigured('You\'re using the dbtemplates\' file system cache backend without having set the DBTEMPLATES_CACHE_DIR setting to a valid value. Make sure the directory exists and is writeable for the user your Django instance is running with.')
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super(FileSystemBackend, self).__init__()
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def _filepath(self, name):
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return os.path.join(self.cache_dir, name)
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def load(self, name):
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try:
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filepath = self._filepath(name)
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return open(filepath).read().decode('utf-8')
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except:
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raise None
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def save(self, name, content, retry=False):
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try:
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filepath = self._filepath(name)
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dirname = os.path.dirname(filepath)
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if not os.path.exists(dirname):
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os.makedirs(dirname)
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cache_file = open(filepath, 'w')
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cache_file.write(force_unicode(content).encode('utf-8'))
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cache_file.close()
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except Exception:
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raise
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def remove(self, name):
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try:
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filepath = self._filepath(name)
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os.remove(filepath)
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except:
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pass
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@ -1,75 +1,32 @@
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import os
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from django.conf import settings
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from django.db.models import signals
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from django.template import TemplateDoesNotExist
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from django.contrib.sites.models import Site
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from django.core.exceptions import ImproperlyConfigured
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from dbtemplates.models import Template
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from dbtemplates.models import Template, backend
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try:
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site = Site.objects.get_current()
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except:
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site = None
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try:
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cache_dir = os.path.normpath(getattr(settings, 'DBTEMPLATES_CACHE_DIR', None))
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if not os.path.isdir(cache_dir):
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raise
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except:
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cache_dir = None
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def load_template_source(template_name, template_dirs=None):
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"""
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Tries to load the template from DBTEMPLATES_CACHE_DIR. If it does not exist
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loads templates from the database by querying the database field ``name``
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with a template path and ``sites`` with the current site,
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and tries to save the template as DBTEMPLATES_CACHE_DIR/``name`` for subsequent
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requests.
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If DBTEMPLATES_CACHE_DIR is not configured falls back to database-only operation.
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Tries to load the template from DBTEMPLATES_CACHE_DIR. If it does not
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exist loads templates from the database by querying the database field
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``name`` with a template path and ``sites`` with the current site,
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and tries to save the template as DBTEMPLATES_CACHE_DIR/``name`` for
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subsequent requests. If DBTEMPLATES_CACHE_DIR is not configured falls
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back to database-only operation.
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"""
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if site is not None:
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if cache_dir is not None:
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filepath = os.path.join(cache_dir, template_name)
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try:
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return (open(filepath).read(), filepath)
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except IOError:
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try:
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t = Template.objects.get(name__exact=template_name, sites__pk=site.id)
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try:
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f = open(filepath, 'w')
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f.write(t.content)
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f.close()
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except IOError:
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try:
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head, tail = os.path.split(filepath)
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if head and not os.path.isdir(head):
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os.makedirs(head)
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except Exception:
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pass
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return (t.content, 'db:%s:%s' % (settings.DATABASE_ENGINE, template_name))
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except:
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pass
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else:
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try:
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t = Template.objects.get(name__exact=template_name, sites__pk=site.id)
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return (t.content, 'db:%s:%s' % (settings.DATABASE_ENGINE, template_name))
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except:
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pass
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display_name = 'db:%s:%s' % (settings.DATABASE_ENGINE, template_name)
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if backend:
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try:
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backend_template = backend.load(template_name)
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if backend_template is not None:
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return backend_template, template_name
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except:
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pass
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try:
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template = Template.objects.get(name__exact=template_name,
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sites__pk=settings.SITE_ID)
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return (template.content, display_name)
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except:
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pass
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raise TemplateDoesNotExist, template_name
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load_template_source.is_usable = True
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def remove_cached_template(instance, **kwargs):
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"""
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Called via django's signals to remove cached templates, if the template in the
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database was changed or deleted.
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"""
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if cache_dir is not None:
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try:
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filepath = os.path.join(cache_dir, instance.name)
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os.remove(filepath)
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except OSError:
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pass
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signals.post_save.connect(remove_cached_template, sender=Template)
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signals.pre_delete.connect(remove_cached_template, sender=Template)
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@ -1,11 +1,13 @@
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# -*- coding: utf-8 -*-
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from datetime import datetime
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from django.db import models
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from django.conf import settings
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from django.db.models import signals
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from django.contrib.sites.models import Site
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from django.utils.translation import gettext_lazy as _
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from django.template import TemplateDoesNotExist
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from django.template.loader import find_template_source
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from django.core.exceptions import ImproperlyConfigured
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class Template(models.Model):
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"""
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@ -14,7 +16,7 @@ class Template(models.Model):
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"""
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name = models.CharField(_('name'), unique=True, max_length=100, help_text=_("Example: 'flatpages/default.html'"))
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content = models.TextField(_('content'), blank=True)
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sites = models.ManyToManyField(Site)
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sites = models.ManyToManyField(Site, default=[settings.SITE_ID])
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creation_date = models.DateTimeField(_('creation date'), default=datetime.now)
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last_changed = models.DateTimeField(_('last changed'), default=datetime.now)
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@ -29,6 +31,8 @@ class Template(models.Model):
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def save(self, *args, **kwargs):
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self.last_changed = datetime.now()
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# If content is empty look for a template with the given name and
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# populate the template instance with its content.
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if not self.content:
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try:
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source, origin = find_template_source(self.name)
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@ -38,6 +42,51 @@ class Template(models.Model):
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pass
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super(Template, self).save(*args, **kwargs)
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# Check if django-reversion is installed and register the model with it if yes
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try:
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models.get_app('reversion')
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except ImproperlyConfigured:
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pass
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else:
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import reversion
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reversion.register(Template)
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def get_cache_backend():
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path = getattr(settings, 'DBTEMPLATES_CACHE_BACKEND', False)
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if path:
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i = path.rfind('.')
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module, attr = path[:i], path[i+1:]
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try:
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mod = __import__(module, {}, {}, [attr])
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except ImportError, e:
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raise ImproperlyConfigured, 'Error importing dbtemplates cache backend %s: "%s"' % (module, e)
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try:
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cls = getattr(mod, attr)
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except AttributeError:
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raise ImproperlyConfigured, 'Module "%s" does not define a "%s" cache backend' % (module, attr)
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return cls()
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return False
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backend = get_cache_backend()
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def add_template_to_cache(instance, **kwargs):
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"""
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Called via Django's signals to cache the templates, if the template
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in the database was added or changed.
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"""
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backend.save(instance.name, instance.content)
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def remove_cached_template(instance, **kwargs):
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"""
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Called via Django's signals to remove cached templates, if the template
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in the database was changed or deleted.
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"""
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backend.remove(instance.name)
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if backend:
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signals.post_save.connect(remove_cached_template, sender=Template)
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signals.post_save.connect(add_template_to_cache, sender=Template)
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signals.pre_delete.connect(remove_cached_template, sender=Template)
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__test__ = {'API_TESTS':"""
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>>> from django.template import loader, Context
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