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"""
Preference models, queryset and managers that handle the logic for persisting preferences.
"""
from django.db import models
from django.db.models.query import QuerySet
from django.conf import settings
from django.utils.functional import cached_property
from django.utils.translation import gettext_lazy as _
from dynamic_preferences.registries import (
preference_models,
global_preferences_registry,
)
from .utils import update
class BasePreferenceModel(models.Model):
"""
A base model with common logic for all preferences models.
"""
#: The section under which the preference is declared
section = models.CharField(
max_length=150,
db_index=True,
blank=True,
null=True,
default=None,
verbose_name=_("Section Name"),
)
#: a name for the preference
name = models.CharField(_("Name"), max_length=150, db_index=True)
#: a value, serialized to a string. This field should not be accessed directly, use :py:attr:`BasePreferenceModel.value` instead
raw_value = models.TextField(_("Raw Value"), null=True, blank=True)
class Meta:
abstract = True
app_label = "dynamic_preferences"
@cached_property
def preference(self):
return self.registry.get(section=self.section, name=self.name, fallback=True)
@property
def verbose_name(self):
return self.preference.get("verbose_name", self.preference.identifier)
verbose_name.fget.short_description = _("Verbose Name")
@property
def help_text(self):
return self.preference.get("help_text", "")
help_text.fget.short_description = _("Help Text")
def set_value(self, value):
"""
Save serialized self.value to self.raw_value
"""
self.raw_value = self.preference.serializer.serialize(value)
def get_value(self):
"""
Return deserialized self.raw_value
"""
return self.preference.serializer.deserialize(self.raw_value)
value = property(get_value, set_value)
def save(self, **kwargs):
if self.pk is None and not self.raw_value:
self.value = self.preference.get("default")
super(BasePreferenceModel, self).save(**kwargs)
def __str__(self):
return self.__repr__()
def __repr__(self):
return "{0} - {1}/{2}".format(self.__class__.__name__, self.section, self.name)
class GlobalPreferenceModel(BasePreferenceModel):
registry = global_preferences_registry
class Meta:
unique_together = ("section", "name")
app_label = "dynamic_preferences"
verbose_name = _("Global preference")
verbose_name_plural = _("Global preferences")
class PerInstancePreferenceModel(BasePreferenceModel):
"""For preferences that are tied to a specific model instance"""
#: the instance which is concerned by the preference
#: use a ForeignKey pointing to the model of your choice
instance = None
class Meta(BasePreferenceModel.Meta):
unique_together = ("instance", "section", "name")
abstract = True
@classmethod
def get_instance_model(cls):
return cls._meta.get_field("instance").remote_field.model
global_preferences_registry.preference_model = GlobalPreferenceModel
# Create default preferences for new instances
from django.db.models.signals import post_save
def invalidate_cache(sender, created, instance, **kwargs):
if not isinstance(instance, BasePreferenceModel):
return
registry = preference_models.get_by_preference(instance)
linked_instance = getattr(instance, "instance", None)
kwargs = {}
if linked_instance:
kwargs["instance"] = linked_instance
manager = registry.manager(**kwargs)
manager.to_cache(instance)
post_save.connect(invalidate_cache)
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