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bfb746f983
* Removed all hardcoded logic for _{fieldname}_cache.
* Added an internal API for interacting with the field values cache.
Thanks carljm and MarkusH for support.
110 lines
3.3 KiB
Python
110 lines
3.3 KiB
Python
from django.db import models
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from django.db.models.fields.related import ForwardManyToOneDescriptor
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from django.utils.translation import get_language
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class ArticleTranslationDescriptor(ForwardManyToOneDescriptor):
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"""
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The set of articletranslation should not set any local fields.
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"""
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def __set__(self, instance, value):
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if instance is None:
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raise AttributeError("%s must be accessed via instance" % self.field.name)
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self.field.set_cached_value(instance, value)
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if value is not None and not self.field.remote_field.multiple:
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self.field.remote_field.set_cached_value(value, instance)
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class ColConstraint:
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# Anything with as_sql() method works in get_extra_restriction().
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def __init__(self, alias, col, value):
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self.alias, self.col, self.value = alias, col, value
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def as_sql(self, compiler, connection):
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qn = compiler.quote_name_unless_alias
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return '%s.%s = %%s' % (qn(self.alias), qn(self.col)), [self.value]
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class ActiveTranslationField(models.ForeignObject):
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"""
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This field will allow querying and fetching the currently active translation
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for Article from ArticleTranslation.
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"""
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requires_unique_target = False
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def get_extra_restriction(self, where_class, alias, related_alias):
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return ColConstraint(alias, 'lang', get_language())
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def get_extra_descriptor_filter(self, instance):
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return {'lang': get_language()}
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def contribute_to_class(self, cls, name):
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super().contribute_to_class(cls, name)
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setattr(cls, self.name, ArticleTranslationDescriptor(self))
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class ActiveTranslationFieldWithQ(ActiveTranslationField):
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def get_extra_descriptor_filter(self, instance):
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return models.Q(lang=get_language())
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class Article(models.Model):
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active_translation = ActiveTranslationField(
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'ArticleTranslation',
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from_fields=['id'],
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to_fields=['article'],
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related_name='+',
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on_delete=models.CASCADE,
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null=True,
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)
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active_translation_q = ActiveTranslationFieldWithQ(
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'ArticleTranslation',
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from_fields=['id'],
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to_fields=['article'],
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related_name='+',
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on_delete=models.CASCADE,
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null=True,
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)
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pub_date = models.DateField()
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def __str__(self):
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try:
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return self.active_translation.title
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except ArticleTranslation.DoesNotExist:
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return '[No translation found]'
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class NewsArticle(Article):
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pass
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class ArticleTranslation(models.Model):
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article = models.ForeignKey(Article, models.CASCADE)
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lang = models.CharField(max_length=2)
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title = models.CharField(max_length=100)
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body = models.TextField()
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abstract = models.TextField(null=True)
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class Meta:
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unique_together = ('article', 'lang')
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ordering = ('active_translation__title',)
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class ArticleTag(models.Model):
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article = models.ForeignKey(
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Article,
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models.CASCADE,
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related_name='tags',
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related_query_name='tag',
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)
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name = models.CharField(max_length=255)
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class ArticleIdea(models.Model):
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articles = models.ManyToManyField(
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Article,
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related_name='ideas',
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related_query_name='idea_things',
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)
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name = models.CharField(max_length=255)
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