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

henrique@bastos.net @henriquebastos http://henriquebastos.net 2

3

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        Welcome  to  the  Django  |  Aprendendo  Python  e  Django  na  prática!        

Welcome  to  the  Django

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  '  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/') (, ('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('\r\n{1}', 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) ...   >>>  type(Subscription(...)) ...  >>  type(Subscription.objects) ...   >>>  type(Subscription.objects.all()) ...   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="henrique@bastos.net", ...          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'henrique@bastos.net' 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

Myproject

Parabéns  {{  subscription.name  }}!

Sua  inscrição  foi  realizada  em   {{  subscription.created_at|date:"d/m/Y"  }}.

Em  breve,  alguém  entrará  em  contato  pelo {%  if  subscription.phone  %} telefone  {{  subscription.phone  }}. {%  else  %} e-­‐mail  {{  subscription.email  }}. {%  endif  %}

                  Template Variables 60

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

Myproject

Parabéns  {{  subscription.name  }}!

Sua  inscrição  foi  realizada  em   {{  subscription.created_at|date:"d/m/Y"  }}.

Em  breve,  alguém  entrará  em  contato  pelo {%  if  subscription.phone  %} telefone  {{  subscription.phone  }}. {%  else  %} e-­‐mail  {{  subscription.email  }}. {%  endif  %}

                  Template Filters 62

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

Myproject

Parabéns  {{  subscription.name  }}!

Sua  inscrição  foi  realizada  em   {{  subscription.created_at|date:"d/m/Y"  }}.

Em  breve,  alguém  entrará  em  contato  pelo {%  if  subscription.phone  %} telefone  {{  subscription.phone  }}. {%  else  %} e-­‐mail  {{  subscription.email  }}. {%  endif  %}

                  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

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