Um raio-x do Django

Um raio-x do Django Henrique Bastos PythonBrasil[9] 1

[email protected] @henriquebastos http://henriquebastos.net 2

Django 4

“ ” Django é o framework web para perfeccionistas com
prazos. #jabá 5

Models Django 6

“ ” Django é o seu banco de dados na
web. #sqn 7

Top Down vs Bottom Up 8

World Wide What? 9

HttpRequest HttpResponse 10

$ curl -‐iv http://welcometothedjango.com.br GET / HTTP/1.1 User-‐Agent: curl/7.19.7 (universal-‐apple-‐darwin10.0)
libcurl/7.19.7 Host: welcometothedjango.com.br Accept: */* HTTP Request 11

$ curl -‐i http://welcometothedjango.com.br/ HTTP/1.1 200 OK Server: nginx/0.7.65 Content-‐Type:
text/html; charset=utf-‐8 Cache-‐Control: max-‐age=600 <html> <head> <title>Welcome to the Django | Aprendendo Python e Django na prática!</title> <link rel="stylesheet" type="text/css" href="/static/css/screen.css" media="screen" /> </head> <body> <h1>Welcome to the Django</h1> </body> </html> HTTP Response 12

django-admin.py startproject myproject Projeto Django 13

repo/ manage.py myproject/ __init__.py settings.py
urls.py wsgi.py Estrutura do Projeto 14

$ python manage.py Usage: manage.py subcommand [options] [args] Options:
-‐v VERBOSITY, -‐-‐verbosity=VERBOSITY Verbosity level; 0=minimal output, 1=normal output, 2=verbose output, 3=very verbose output -‐-‐settings=SETTINGS The Python path to a settings module, e.g. "myproject.settings.main". If this isn't provided, the DJANGO_SETTINGS_MODULE environment variable will be used. -‐-‐pythonpath=PYTHONPATH A directory to add to the Python path, e.g. "/home/djangoprojects/myproject". -‐-‐traceback Print traceback on exception -‐-‐version show program's version number and exit -‐h, -‐-‐help show this help message and exit Type 'manage.py help <subcommand>' for help on a specific subcommand. Available subcommands: ... 15

Um pacote Python que contém um módulo models.py Django App
16

repo/ manage.py myproject/ __init__.py settings.py
urls.py wsgi.py myapp/ __init__.py models.py tests.py views.py Estrutura da App 17

INSTALLED_APPS = ( 'django.contrib.auth',
'django.contrib.contenttypes', 'django.contrib.sessions', 'django.contrib.sites', 'django.contrib.messages', 'django.contrib.staticfiles', # Uncomment the next line to enable the admin: # 'django.contrib.admin', # Uncomment the next line to enable admin documentation: # 'django.contrib.admindocs', 'myproject.myapp', ) myproject/settings.py 18

$ manage runserver Validating models... 0 errors found Django version
1.5.2, using settings 'myproject.settings' Development server is running at http://127.0.0.1:8000/ Quit the server with CONTROL-‐C. 19

1. Request Middleware 2. Url Resolve 3. View Middleware 4.
View 5. Template Response Middleware 6. Response Middleware Request Handler 20

Url Resolve 21

URLConf Um módulo que contém uma variável urlpatterns que referencia
uma sequência de rotas associadas à views. 22

urlpatterns = patterns('', url('^time/plus/1/$', one_hour_ahead),
url('^time/plus/2/$', two_hours_ahead), ... url('^time/plus/24/$', tons_hours_ahead), ) Exemplo 23

urlpatterns = patterns('', url('^time/plus/(\d{1,2})/$', time_ahead), ) Bem
melhor... 24

Expressões Regulares http://docs.python.org/library/re.html#re-syntax http://www.pythonregex.com/ 25

URL Resolvers $ manage shell >>> from django.core.urlresolvers import reverse,
resolve >>> resolve('/inscricao/1/') (<function myproject.myapp.views.myview>, ('1',), {}) >>> reverse('myapp:detail', args=[1]) '/inscricao/1/' 26

Views Um callable que recebe uma instância de HttpRequest e
retorna uma instância de HttpResponse. 27

# coding: utf-8 from django.http import HttpResponse def myview(request): return
HttpResponse('Opa!') A view mais simples do mundo. 28

Anti-patterns Views grandes; Conversões de dados na view; Pilhas de
decoradores; Uso de funções auxiliares que instanciam o HttpResponse; Contextos de templates gigantes; 29

Forms Muito além de formulários... 30

Arquitetura dos Forms Forms Responsável pelo pipeline de validação Fields
Valida dados da requisição e os converte para tipos Python Widgets Representa o valor do ﬁeld em html. 31

Form Fields BooleanField CharField ChoiceField TypedChoiceField DateField DateTimeField DecimalField EmailField
FileField FilePathField FloatField ImageField IntegerField IPAddressField MultipleChoiceField NullBooleanField RegexField SlugField TimeField URLField 32

Form Widgets Input TextInput PasswordInput HiddenInput MultipleHiddenInput FileInput ClearableFileInput Textarea
DateInput DateTimeInput TimeInput CheckboxInput Select NullBooleanSelect SelectMultiple RadioInput RadioFieldRenderer RadioSelect CheckboxSelectMultiple MultiWidget 33

Anatomia de um FormField 34

class IntegerField(Field): default_error_messages = { 'invalid': _(u'Enter a whole number.'),
'max_value': _(u'Ensure this value is less than or equal to %(limit_value)s.'), 'min_value': _(u'Ensure this value is greater than or equal to %(limit_value)s.'), } def __init__(self, max_value=None, min_value=None, *args, **kwargs): super(IntegerField, self).__init__(*args, **kwargs) if max_value is not None: self.validators.append(validators.MaxValueValidator(max_value)) if min_value is not None: self.validators.append(validators.MinValueValidator(min_value)) def to_python(self, value): """ Validates that int() can be called on the input. Returns the result of int(). Returns None for empty values. """ value = super(IntegerField, self).to_python(value) if value in validators.EMPTY_VALUES: return None if self.localize: value = formats.sanitize_separators(value) try: value = int(str(value)) except (ValueError, TypeError): raise ValidationError(self.error_messages['invalid']) return value 35

Anatomia de um Widget 36

class Textarea(Widget): def __init__(self, attrs=None): # The 'rows' and 'cols'
attrs are required for HTML correctness. default_attrs = {'cols': '40', 'rows': '10'} if attrs: default_attrs.update(attrs) super(Textarea, self).__init__(default_attrs) def render(self, name, value, attrs=None): if value is None: value = '' final_attrs = self.build_attrs(attrs, name=name) return format_html('<textarea{0}>\r\n{1}</textarea>', flatatt(final_attrs), force_text(value)) 37

Bounded SubscriptionForm(request.POST) ou seja, com dados vs Unbounded SubscriptionForm() ou
seja, sem dados 38

Dentro do form.is_valid() 1. Se Form for bounded... 2. Form
full_clean() 3. Para cada Field é executado: 3.1. clean() do Field 3.2. validators do Field 3.3. método clean_* se existir no Form 4. Form clean() 5. errors ou cleaned_data 39

Models 40

# coding: utf-8 from django.db import models class Subscription(models.Model): name
= models.CharField(max_length=100) cpf = models.CharField(max_length=11) email = models.EmailField() phone = models.CharField(max_length=20, blank=True) created_at = models.DateTimeField(auto_now_add=True) class Meta: ordering = ['created_at'] def __unicode__(self): return self.name Model 41

CREATE TABLE "myapp_subscription" ( "id" integer NOT
NULL PRIMARY KEY, "name" varchar(100) NOT NULL, "cpf" varchar(11) NOT NULL UNIQUE, "email" varchar(75) NOT NULL UNIQUE, "phone" varchar(20) NOT NULL, "created_at" datetime NOT NULL ); 42

Cada um no seu quadrado >>> type(Subscription) ... <class 'django.db.models.base.ModelBase'>
>>> type(Subscription(...)) ... <class 'myproject.myapp.models.Subscription' >>> type(Subscription.objects) ... <class 'django.db.models.manager.Manager'> >>> type(Subscription.objects.all()) ... <class 'django.db.models.query.QuerySet'> 43

Cada um no seu quadrado >>> Subscription ... Descreve a
estrutura de uma tabela >>> Subscription(...) ... Corresponde à uma linha da tabela >>> Subscription.objects ... Manipula todas as linhas da tabela >>> Subscription.objects.all() ... Acumula estados que serão usados pelo ORM para ... compilar uma query SQL 44

Model Fields Correlacionam atributos do modelo com colunas da tabela
45

Insert e Update 46

$ manage shell >>> from myproject.myapp.models import Subscription >>> s
= Subscription( ... name="Henrique Bastos", ... cpf="12345678901", ... email="[email protected]", ... phone="21-‐9618-‐6180") >>> s.save() 47

$ manage shell >>> s.id ... 1 >>> s.pk #
property que neste caso retorna s.id ... 1 >>> s.phone="234-‐5678" >>> s.save() # update, pois s já tem id 48

Seleção e Filtro 49

>>> # instancia um QuerySet >>> qs = Subscription.objects.all()
>>> # realiza a query no banco apenas quando necessário >>> print qs [Henrique Bastos] >>> qs[0].email # retorna o email do 1º elemento u'[email protected]' 50

Selecionando 1 único objeto >>> s = Subscription.objects.get(name__contains="Bas") >>> s.phone
u'21-‐9618-‐6180' 51

Filtros >>> qs = Subscription.objects.filter(name__startswith="H") >>> qs[0].phone u'21-‐9618-‐6180' 52

Encadeamento >>> qs = Subscription.objects.all() >>> qs = qs.filter(name__contains="Bas") >>>
qs = qs.order_by("name") Subscription.objects.filter(name__contains="Bas").order_by("name") 53

Field Lookup exact iexact contains icontains in gt gte lt
lte startswith istartswith endswith iendswith ... https://docs.djangoproject.com/en/1.5/topics/db/queries/#ﬁeld-lookups 54

Ordenação # Ascendente Subscription.objects.order_by("name") # Descendente Subscription.objects.order_by("-‐name") 55

Slicing limita a sua query Subscription.objects.all()[0] Subscription.objects.all()[0:2] Subscription.objects.all()[-‐1] # NOT
56

Subscription.objects.all().update(name="Outro Nome") Subscription.objects.all().delete() Update e Delete múltiplo 57

abstract app_label db_table db_tablespace ordering proxy unique_together verbose_name verbose_name_plural ...
Meta https://docs.djangoproject.com/en/1.5/ref/models/options/ 58

Templates 59

<!DOCTYPE HTML PUBLIC "-‐//W3C//DTD HTML 4.01//EN"> <html> <head><title>Myproject</title></head> <body> <img
src="{{ STATIC_URL }}img/logo.png" /> <h1>Parabéns {{ subscription.name }}!</h1> <p> Sua inscrição foi realizada em {{ subscription.created_at|date:"d/m/Y" }}. </p> <p> Em breve, alguém entrará em contato pelo {% if subscription.phone %} telefone {{ subscription.phone }}. {% else %} e-‐mail {{ subscription.email }}. {% endif %} </p> </body> </html> Template Variables 60

{{ subscription.name }} 1. subscription["name"] 2. subscription.name 3. subscription.name() O
ponto-chave 61

src="{{ STATIC_URL }}img/logo.png" /> <h1>Parabéns {{ subscription.name }}!</h1> <p> Sua inscrição foi realizada em {{ subscription.created_at|date:"d/m/Y" }}. </p> <p> Em breve, alguém entrará em contato pelo {% if subscription.phone %} telefone {{ subscription.phone }}. {% else %} e-‐mail {{ subscription.email }}. {% endif %} </p> </body> </html> Template Filters 62

{{ subscription.created_at|date:"d/m/Y" }} {{ text|escape|linebreaks }} {{ text|truncatewords:"30" }} 63

src="{{ STATIC_URL }}img/logo.png" /> <h1>Parabéns {{ subscription.name }}!</h1> <p> Sua inscrição foi realizada em {{ subscription.created_at|date:"d/m/Y" }}. </p> <p> Em breve, alguém entrará em contato pelo {% if subscription.phone %} telefone {{ subscription.phone }}. {% else %} e-‐mail {{ subscription.email }}. {% endif %} </p> </body> </html> Template Tags 64

# coding: utf-8 from django.http import HttpResponse from django.template import
loader, RequestContext def homepage(request): t = loader.get_template('index.html') c = RequestContext(request) content = t.render(c) return HttpResponse(content) Uso de Templates 65

Include vs Extends 66

https://docs.djangoproject.com/en/1.5/ref/templates/builtins/ 68

Um raio-x do Django

Um raio-x do Django

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