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e542e81b39
The old names were downright confusing. Some seemed to mean the opposite
of what the class actually did.
The new names follow a consistent nomenclature:
(Forward|Reverse)(ManyToOne|OneToOne|ManyToMany)Descriptor.
I mentioned combinations that do not exist in the docstring in order to
help people who would search for them in the code base.
99 lines
3.0 KiB
Python
99 lines
3.0 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.encoding import python_2_unicode_compatible
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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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setattr(instance, self.cache_name, value)
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if value is not None and not self.field.remote_field.multiple:
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setattr(value, self.field.related.get_cache_name(), instance)
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class ColConstraint(object):
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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(ActiveTranslationField, self).contribute_to_class(cls, name)
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setattr(cls, self.name, ArticleTranslationDescriptor(self))
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@python_2_unicode_compatible
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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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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.CharField(max_length=400, 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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