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73 lines
2.1 KiB
Python
73 lines
2.1 KiB
Python
'''
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******
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fields
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******
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Contains two custom fields:
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* :class:`EavSlugField`
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* :class:`EavDatatypeField`
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Classes
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-------
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'''
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import re
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from django.core.exceptions import ValidationError
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from django.db import models
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from django.utils.translation import ugettext_lazy as _
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class EavSlugField(models.SlugField):
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'''
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The slug field used by :class:`~eav.models.Attribute`
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'''
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def validate(self, value, instance):
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'''
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Slugs are used to convert the Python attribute name to a database
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lookup and vice versa. We need it to be a valid Python identifier.
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We don't want it to start with a '_', underscore will be used
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var variables we don't want to be saved in db.
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'''
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super(EavSlugField, self).validate(value, instance)
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slug_regex = r'[a-z][a-z0-9_]*'
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if not re.match(slug_regex, value):
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raise ValidationError(_(u"Must be all lower case, " \
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u"start with a letter, and contain " \
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u"only letters, numbers, or underscores."))
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@staticmethod
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def create_slug_from_name(name):
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'''
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Creates a slug based on the name
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'''
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name = name.strip().lower()
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# Change spaces to underscores
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name = '_'.join(name.split())
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# Remove non alphanumeric characters
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return re.sub('[^\w]', '', name)
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class EavDatatypeField(models.CharField):
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'''
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The datatype field used by :class:`~eav.models.Attribute`
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'''
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def validate(self, value, instance):
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'''
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Raise ``ValidationError`` if they try to change the datatype of an
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:class:`~eav.models.Attribute` that is already used by
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:class:`~eav.models.Value` objects.
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'''
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super(EavDatatypeField, self).validate(value, instance)
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if not instance.pk:
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return
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if type(instance).objects.get(pk=instance.pk).datatype == instance.datatype:
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return
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if instance.value_set.count():
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raise ValidationError(_(u"You cannot change the datatype of an "
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u"attribute that is already in use."))
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