107 lines
3.0 KiB
Python
107 lines
3.0 KiB
Python
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"""
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Tests for field subclassing.
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"""
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from django.db import models
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from django.utils.encoding import force_unicode
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from django.core import serializers
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class Small(object):
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"""
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A simple class to show that non-trivial Python objects can be used as
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attributes.
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"""
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def __init__(self, first, second):
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self.first, self.second = first, second
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def __unicode__(self):
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return u'%s%s' % (force_unicode(self.first), force_unicode(self.second))
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def __str__(self):
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return unicode(self).encode('utf-8')
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class SmallField(models.Field):
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"""
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Turns the "Small" class into a Django field. Because of the similarities
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with normal character fields and the fact that Small.__unicode__ does
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something sensible, we don't need to implement a lot here.
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"""
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__metaclass__ = models.SubfieldBase
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def __init__(self, *args, **kwargs):
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kwargs['max_length'] = 2
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super(SmallField, self).__init__(*args, **kwargs)
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def get_internal_type(self):
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return 'CharField'
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def to_python(self, value):
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if isinstance(value, Small):
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return value
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return Small(value[0], value[1])
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def get_db_prep_save(self, value):
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return unicode(value)
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def get_db_prep_lookup(self, lookup_type, value):
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if lookup_type == 'exact':
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return force_unicode(value)
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if lookup_type == 'in':
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return [force_unicode(v) for v in value]
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if lookup_type == 'isnull':
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return []
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raise TypeError('Invalid lookup type: %r' % lookup_type)
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def flatten_data(self, follow, obj=None):
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return {self.attname: force_unicode(self._get_val_from_obj(obj))}
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class MyModel(models.Model):
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name = models.CharField(max_length=10)
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data = SmallField('small field')
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def __unicode__(self):
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return force_unicode(self.name)
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__test__ = {'API_TESTS': ur"""
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# Creating a model with custom fields is done as per normal.
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>>> s = Small(1, 2)
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>>> print s
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12
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>>> m = MyModel(name='m', data=s)
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>>> m.save()
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# Custom fields still have normal field's attributes.
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>>> m._meta.get_field('data').verbose_name
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'small field'
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# The m.data attribute has been initialised correctly. It's a Small object.
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>>> m.data.first, m.data.second
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(1, 2)
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# The data loads back from the database correctly and 'data' has the right type.
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>>> m1 = MyModel.objects.get(pk=m.pk)
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>>> isinstance(m1.data, Small)
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True
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>>> print m1.data
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12
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# We can do normal filtering on the custom field (and will get an error when we
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# use a lookup type that does not make sense).
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>>> s1 = Small(1, 3)
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>>> s2 = Small('a', 'b')
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>>> MyModel.objects.filter(data__in=[s, s1, s2])
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[<MyModel: m>]
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>>> MyModel.objects.filter(data__lt=s)
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Traceback (most recent call last):
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...
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TypeError: Invalid lookup type: 'lt'
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# Serialization works, too.
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>>> stream = serializers.serialize("json", MyModel.objects.all())
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>>> stream
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'[{"pk": 1, "model": "field_subclassing.mymodel", "fields": {"data": "12", "name": "m"}}]'
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>>> obj = list(serializers.deserialize("json", stream))[0]
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>>> obj.object == m
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True
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"""}
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