109 lines
3.2 KiB
Python
109 lines
3.2 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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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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