Presentación realizada para el evento DynLang Encuentro de Charlistas realizado en Santiago de Chile el 29 de marzo de 2015.

1. Lo nuevo de Django
Pedro Burón

4. Django Unchained
Pedro Burón

5. Agenda
• Django 1.7
– App loading framework
– Forms
– Querysets
– Schema Migrations

6. Agenda
• Django 1.8
– Postgres specifics
– Conditional expressions
– Template Engines

7. Agenda
• Django 1.7
– Schema Migrations
• Django 1.8
– Conditional expressions
– Template Engines

8. App Loading
Framework

9. AppConfig
from django.apps import AppConfig
class RockNRollConfig(AppConfig):
name = 'rock_n_roll'
verbose_name = "Rock ’n’ roll”
class GypsyJazzConfig(RockNRollConfig):
verbose_name = "Gypsy jazz“
INSTALLED_APPS = [
'anthology.apps.GypsyJazzConfig',
# ...
]

10. Forms

11. Forms add error
def clean(self):
cleaned_data = super(ContactForm, self).clean()
cc_myself = cleaned_data.get("cc_myself")
subject = cleaned_data.get("subject")
if cc_myself and subject and "help" not in subject:
msg = u"Must put 'help' in subject."
self.add_error('cc_myself', msg)
self.add_error('subject', msg)

12. Querysets

13. Queryset as managers
class MyQueryset(models.QuerySet):
def published(self):
return self.filter(published=True)
class MyModel(models.Model):
objects = MyQueryset.as_manager()
...

14. Schema Migrations

16. Thanks to:
Andrew Godwin

17. Migrations directory
$ ./manage.py startapp myapp
$ tree
.
|-- djangounchained
| |-- settings.py
| |-- urls.py
| `-- wsgi.py
|-- manage.py
`-- myapp
|-- admin.py
|-- migrations
|-- models.py
`-- views.py

18. Models
# models.py
class Entry(models.Model):
title = models.CharField(…)
content = models.TextField()
slug = models.SlugField(…)

19. Make migrations
$ ./manage.py makemigrations myapp

20. The Migration File
class Migration(migrations.Migration):
dependencies = []
operations = [
migrations.CreateModel(
name='Entry',
fields=[
('id', models.AutoField(verbose_name='ID', serialize=False,
auto_created=True, primary_key=True)),
('title', models.CharField(max_length=200)),
('content', models.TextField()),
('slug', models.SlugField(unique=True, max_length=200)),
],
options={
},
bases=(models.Model,),
),
]

21. Migrate
$ ./manage.py migrate myapp

22. The Operations
• CreateModel
• DeleteModel
• AddField
• AlterField
• AlterModelTable
• RunSQL
• RunPython

23. CreateModel
migrations.CreateModel(
name='Person',
fields=[
('id', models.AutoField(verbose_name='ID',
serialize=False, auto_created=True,
primary_key=True)),
('full_name’,models.CharField(max_length=100)),
],
options={},
bases=(models.Model,),
)

24. AddField
dependencies = [
('people', '0001_initial'),
]
operations = [
migrations.AddField(
model_name='person',
name='first_name',
field=models.CharField(default='',
max_length=50),
preserve_default=False,
),

25. RunPython
def split_names(apps, schema_editor):
Person = apps.get_model('people.Person')
for person in Person.objects.all():
full_name = person.full_name.split(' ')
person.first_name = full_name[0:-1]
person.last_name = last_name[-1]
person.save()
migrations.RunPython(
split_names,
merge_names
)

26. RemoveField
dependencies = [
('people', '0003_split_full_name'),
]
operations = [
migrations.RemoveField(
model_name='person',
name='full_name',
),
]

27. DJANGO 1.8
luego, muy luego...

28. Postgres Specific

29. ArrayField
class ChessBoard(models.Model):
board = ArrayField(
ArrayField(
models.CharField(max_length=10, blank=True),
size=8,
),
size=8,
)

30. HStoreField
class Dog(models.Model):
name = models.CharField(max_length=200)
data = HStoreField()
>>> Dog.objects.create(name='Rufus',
data={'breed': 'labrador'})
>>> Dog.objects.filter(
data__breed='labrador')

31. RangeField
class Event(models.Model):
name = models.CharField(max_length=200)
ages = IntegerRangeField()
>>> Event.objects.create(name='Soft play',
ages=(0, 10))
>>> Event.objects.create(name='Pub trip',
ages=(21, None))
>>> Event.objects.filter(
ages__contains=NumericRange(4, 5))
[<Event: Soft play>]

32. Unaccent!
User.objects.filter(
first_name__unaccent__startswith="Revolv")

33. Conditionals
Expressions

34. SQL Conditional Field
SELECT
”client"."name",
CASE
WHEN ”client"."account_type" = 'G’
THEN '5%'
WHEN ”client"."account_type" = 'P’
THEN '10%' ELSE '0%'
END AS "discount"
FROM
”client"

35. Case, When
>>> Client.objects.annotate(
... discount=Case(
... When(account_type=Client.GOLD,
... then=Value('5%')),
... When(account_type=Client.PLATINUM,
... then=Value('10%')),
... default=Value('0%'),
... output_field=CharField(),
... ),
... ).values_list('name', 'discount')

36. Conditional Update
for cl in Client.objects.all():
if cl.registered <= a_year_ago:
client.account_type = GOLD
elif cl.registerd <= a_month_ago:
client.account_type = PLATINUM
else:
client.account_type = REGULAR
client.save()

37. Conditional Update
Client.objects.update(
account_type=Case(
When(
registered_on__lte=a_year_ago,
then=Value(Client.PLATINUM)),
When(
registered_on__lte=a_month_ago,
then=Value(Client.GOLD)),
default=Value(Client.REGULAR)
),
)

38. Template Engines

39. TEMPLATES setting
TEMPLATES = [
{
'BACKEND':
'django.template.backends.django.DjangoTemplates',
#'django.template.backends.jinja2.Jinja2'
'DIRS': [],
'APP_DIRS': True,
'OPTIONS': {},
},
]

40. Multiple Template Engines
TEMPLATES = [
{
’NAME': 'django'
'BACKEND':
'django.template.backends.django.DjangoTemplates',
},
{
’NAME': ’jinja2'
'BACKEND':
'django.template.backends.jinja2.Jinja2',
},
]

41. My Custom Engine

42. MyEngine
class MyEngine(BaseEngine):
app_dirname = 'dummy'
def __init__(self, params):
...
def from_string(self, template_code):
...
def get_template(self, template_name):
...

43. Template Wrapper
class Template(object):
def __init__(self, template):
...
def render(self, context=None,
request=None):
...

45. Django Unchained
Pedro Burón
pedroburonv@gmail.com
http://github.com/pedroburon
GRACIAS!