def test_transform(self):
with register_lookup(IntegerField, Chr):
authors = Author.objects.annotate(name_code_point=Ord('name'))
self.assertCountEqual(
authors.filter(name_code_point__chr=Chr(ord('J'))),
[self.john])
self.assertCountEqual(
authors.exclude(name_code_point__chr=Chr(ord('J'))),
[self.elena, self.rhonda])
def test_chr(self):
Author.objects.create(name='John Smith', alias='smithj')
Author.objects.create(name='Élena Jordan', alias='elena')
Author.objects.create(name='Rhonda')
authors = Author.objects.annotate(first_initial=Left('name', 1))
self.assertQuerysetEqual(authors.filter(first_initial=Chr(ord('J'))),
['John Smith'], lambda x: x.name)
self.assertQuerysetEqual(
authors.exclude(first_initial=Chr(ord('J'))),
['Élena Jordan', 'Rhonda'],
lambda x: x.name,
ordered=False,
)
def test_chr_transform(self):
try:
IntegerField.register_lookup(Chr, 'chr')
Author.objects.create(name='John Smith', alias='smithj')
Author.objects.create(name='Élena Jordan', alias='elena')
Author.objects.create(name='Rhonda')
authors = Author.objects.annotate(name_code_point=Ord('name'))
self.assertQuerysetEqual(
authors.filter(name_code_point__chr=Chr(ord('J'))),
['John Smith'], lambda x: x.name)
self.assertQuerysetEqual(
authors.exclude(name_code_point__chr=Chr(ord('J'))),
['Élena Jordan', 'Rhonda'],
lambda x: x.name,
ordered=False,
)
finally:
IntegerField._unregister_lookup(Chr, 'chr')
def test_non_ascii(self):
authors = Author.objects.annotate(first_initial=Left("name", 1))
self.assertCountEqual(authors.filter(first_initial=Chr(ord("É"))),
[self.elena])
self.assertCountEqual(authors.exclude(first_initial=Chr(ord("É"))),
[self.john, self.rhonda])
def test_basic(self):
authors = Author.objects.annotate(first_initial=Left('name', 1))
self.assertCountEqual(authors.filter(first_initial=Chr(ord('J'))),
[self.john])
self.assertCountEqual(authors.exclude(first_initial=Chr(ord('J'))),
[self.elena, self.rhonda])
#!/usr/bin/env python
from django.db.models.functions import Chr
from .models import MyModel
"""
https://docs.djangoproject.com/en/dev/ref/models/database-functions/#chr
class Chr(expression, **extra)
"""
qs = MyModel.objects.filter(name__startswith=Chr(ord('M')))
for r in qs.all():
print(r.name)