91django_基本使用

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目錄

django. 1

django-admin startproject. 3

django-admin startapp. 5

model：... 7

view中使用model：... 10

template. 11

view中使用template：... 13

去掉url和static硬編碼：... 15

url反解析：... 15

url命名空間：... 15

form處理：... 16

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django

是py下一款著名的web框架；

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框架，是整個或部分系統的可重用設計，表現為一組抽象構件及構件實例間交互的方法；

是可被應用開發者定制的應用骨架；

其它web框架：flask、tornado；

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django優：

自帶輪子眾多，方便快速開發，如ORM、Auth、Cache、Template、From核心組件；

天生的MVC設計模式；

實用且強大的管理后臺；

簡潔的url設計；

周邊插件豐富；

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django缺：

重；

同步阻塞；

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django設計哲學：

大而全；

快速開發；

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django歷史：

最初開發者，Adrian和Simon；

開發背景，World Online維護幾個新聞站點，要求快速發布新聞，快速建立其它新聞站點（快速開發、數據驅動）；

World Online于05年夏天開源；

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https://www.djangoproject.com/

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(django) C:\django>pip install django==1.11

(django) C:\django>ipython

In [1]: import django

In [2]: django.get_version()

Out[2]: '1.11'

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響應流程：

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django-admin startproject

pycharm，New Project-->webproject，C:\webproject

(webproject) C:\webproject>django-admin startproject mysite?? #或用python manage.py startproject mysite；此命令腳本在虛擬環境的C:\Users\Administrator\py_env\webproject\Scriptsdjango-admin.exe

mysite/mysite/sessings.py?? #項目配置

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mysite/mysite/urls.py?? #入口url

def url(regex, view, kwargs=None, name=None):?? #view是function object，不是函數調用；view函數的第一參數永遠是request，不探討CBV，view函數的返回值永遠是HttpResponse對象，顯式或隱式；

url(r'^hello/$', hello),?? #django默認會給url后加/，此處定義，hello前不帶/，hello后一定要有/，這樣即使用戶訪問http://127.0.0.1:8000/hello也會自動跳到http://127.0.0.1:8000/hello/上；若此處配置為r'^hello$'，用戶訪問http://127.0.0.1:8000/hello/，訪問的地址無論是否帶/都會報404；所以記住，此處定義的url，hello前沒有/，hello后要有/；

url(r'^$', views.index, name='index')?? #app中的urls.py，可通過name反解出url；

url(r'^polls/', include('polls.urls')),?? #項目中的urls.py，include里是str，在用到時才動態導入；

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mysite/mysite/wsgi.py?? #生產部署時調用

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注：

include源碼，from django.conf.urls import url, include：

def include(arg, namespace=None, app_name=None):

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例：

urls.py

from django.conf.urls import url

from django.contrib import admin

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from django.http import HttpResponse

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def index(request):

??? return HttpResponse('this is index')

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def hello(request):?? #view函數的第一個參數永遠是request，不探討CBV

??? return HttpResponse('Hello world')

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urlpatterns = [?? #urlpatterns約定俗成的名字

??? url(r'^$', index),

??? url(r'^hello/$', hello),?? #django默認會給url后加/，此處定義，hello前不帶/，hello后一定要有/，這樣即使用戶訪問http://127.0.0.1:8000/hello也會自動跳到http://127.0.0.1:8000/hello/上；若此處配置為r'^hello$'，用戶訪問http://127.0.0.1:8000/hello/，訪問的地址無論是否帶/都會報404；所以記住，此處定義的url，hello前沒有/，hello后要有/

??? url(r'^admin/', admin.site.urls),

]

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(webproject) C:\webproject\mysite>python manage.py runserver?? #可自定義ip:port，python manage.py runserver 0.0.0.0:8080，啟動的是django內置webserver，用于測試

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django-admin startapp

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django app與django project區別：

app中才能用model；

app設計是可插拔的，app不一定在project中；

settings.py中有內置的app，可根據項目情況禁用；

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(webproject) C:\webproject\mysite>django-admin startapp polls?? #或用python manage.py startapp polls，新建投票app，在項目根下操作

admin.py?? #后臺管理

apps.py?? #1.8ver后加的，app的獨立配置

tests.py?? #測試用例

views.py?? #業務邏輯

migrations/?? #與model的版本控制有關

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例：

mysite/mysite/settings.py?? #在項目settings.py中導入app

INSTALLED_APPS = [

??? 'polls.apps.PollsConfig',

??? 'django.contrib.admin',

??? 'django.contrib.auth',

??? 'django.contrib.contenttypes',

??? 'django.contrib.sessions',

??? 'django.contrib.messages',

??? 'django.contrib.staticfiles',

]

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mysite/polls/views.py

from django.shortcuts import render

from django.http import HttpResponse

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def index(request):

??? return HttpResponse('this is index at polls')

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mysite/polls/urls.py?? #app中的urls.py默認不存在，新建

urlpatterns = [

??? url(r'^$', views.index, name='index')

]

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mysite/mysite/urls.py

urlpatterns = [

??? url(r'^polls/', include('polls.urls')),?? #include中是str，在用到時才動態導入

??? url(r'^admin/', admin.site.urls),

]

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model：

支持sqlite、mysql、postgresql、oracle；

py3.5以上版本，不支持MySQLdb驅動；

可用pymysql，py寫的；

可用mysqlclient，c寫的，速度快，fork的MySQLdb，官方推薦；

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ORM，用py的方法、數據結構，來訪問db，可兼容不同的DB；

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一個class代表一張表，多對多會產生額外一張關系表；

默認pk為id，也可自定義pk；

表名默認為$APP_NAME$CLASS_NAME.lower()，表名小寫（跨平臺支持），可重寫；

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models migrations：

定義好models.py需應用到db，django為了能跟蹤表結構的變化，增加了migration版本控制功能，如果沒有該功能，需手動編寫表結構變化的語句，重新導入數據；

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models CRUD：

增：

q = Question(**kwargs)?? #方式1

q.save()

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q = Question.objects.create(**kwargs)?? #方式2

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刪：

q = Question.objects.get(id=1)

q.delete()

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Question.objects.filter(id=1).delete()

Question.objects.all().delete()

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改：

q = Question.objects.get(id=1)

q.question_text = 'some text'

q.save()

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Question.objects.filter(id=1).update(question_text='why ?')

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查：

Question.objects.all()

Question.objects.filter(question_text="what's up?")?? #objects，model默認的manager管理器

Question.objects.get(id=1)

latest_question_list = Question.objects.order_by('-pub_date')[:3]?? #默認升序，加上-倒序

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注：

>>> from django.utils import timezone

>>> import datetime

>>> timezone.now()?? #比datetime.datetime.now()多了時區，在頁面展示時，django內部會轉為適合用戶所在的時區

datetime.datetime(2019, 1, 2, 7, 2, 18, 244920, tzinfo=<UTC>)

>>> datetime.datetime.now()

datetime.datetime(2019, 1, 2, 15, 2, 32, 837755)

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models中方法：

def __str__(self):

???????? return self.question_text

def was_published_recently(self):

???????? return self.pub_date >= timezone.now() - datetime.timedelta(days=1)

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mysite/mysite/settings.py

DATABASES = {

??? 'default': {

??????? 'ENGINE': 'django.db.backends.sqlite3',

??????? 'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),

??? }

}

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mysite/polls/models.py

from django.db import models

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class Question(models.Model):?? #一個class代表一張表，多對多會產生額外一張關系表；默認pk為id，也可自定義pk；表名默認為$APP_NAME$CLASS_NAME.lower()，可重寫

??? question_text = models.CharField(max_length=200)

??? pub_date = models.DateTimeField('date published')

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class Choice(models.Model):

??? question = models.ForeignKey(Question, on_delete=models.CASCADE)

??? choice_text = models.CharField(max_length=200)

??? votes = models.IntegerField(default=0)

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(webproject) C:\webproject\mysite>python manage.py makemigrations?? #生成遷移記錄

(webproject) C:\webproject\mysite>python manage.py migrate?? #應用到db

(webproject) C:\webproject\mysite>sqlite3 db.sqlite3

sqlite> .tables

auth_group????????????????? django_admin_log

auth_group_permissions????? django_content_type

auth_permission??? ?????????django_migrations

auth_user?????????????????? django_session

auth_user_groups??????????? polls_choice

auth_user_user_permissions? polls_question

sqlite> .quit

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(webproject) C:\webproject\mysite>dir polls\migrations\

?驅動器 C 中的卷是 OS

?卷的序列號是 000B-5D26

C:\webproject\mysite\polls\migrations 的目錄

2019/01/02? 14:24??? <DIR>????????? .

2019/01/02? 14:24??? <DIR>????????? ..

2019/01/02? 14:24???????????? 1,266 0001_initial.py

2019/01/02? 11:29???????????????? 0 __init__.py

2019/01/02? 14:25??? <DIR>????????? __pycache__

?????????????? 2 個文件????????? 1,266 字節

?????????????? 3 個目錄 77,168,365,568 可用字節

(webproject) C:\webproject\mysite>python manage.py sqlmigrate polls 0001_initial?? #查看sql語句是否是指定要求的

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(webproject) C:\webproject\mysite>python manage.py shell? ?#進入交互式命令行

>>> from django.utils import timezone

>>> from polls.models import Question,Choice

>>> q = Question(question_text="what's new", pub_date=timezone.now())

>>> q.save()

>>> q.id

1

>>> q.pk

1

>>> q.question_text

"what's new"

>>> q.pub_date

datetime.datetime(2019, 1, 2, 6, 49, 16, 612213, tzinfo=<UTC>)

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>>> from polls.models import Question,Choice

>>> from django.utils import timezone

>>> q = Question.objects.create(question_text="how are you?", pub_date=timezone.now())

>>> q = Question.objects.create(question_text="what's the weather?", pub_date=timezone.now())

>>> q = Question.objects.create(question_text="fuck you!", pub_date=timezone.now())

>>> q

<Question: fuck you!>

>>> q.was_published_recently()

True

>>> d = timezone.now() - timezone.timedelta(days=2)

>>> q.pub_date = d

>>> q.save()

>>> q.was_published_recently()

False

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view中使用model：

from django.http import HttpResponse

from .models import Question

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def index(request):

??? latest_question_list = Question.objects.order_by('-pub_date')[:3]?? #默認升序，加上-倒序

??? output = ', '.join([q.question_text for q in latest_question_list])

??? return HttpResponse(output)

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def detail(request, question_id):

??? return HttpResponse('Your are looking at question {}'.format(question_id))

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def results(request, question_id):

??? response = 'Your are looking at results of question {}'.format(question_id)

??? return HttpResponse(response)

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def vote(request, question_id):

??? return HttpResponse('Your are voting on question {}'.format(question_id))

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template

django內置了自己的模板引擎，和jinja很像，使用簡單；

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django默認會在app_name/templates/下尋找模板，在app_name/templates/下再建立app_name，這樣app_name/templates/app_name/下存放與該app相關的模板，因為默認django會去所有的app下找模板，可能會優先找到其它app下的模板；

默認會到app_name/static/下尋找靜態文件；

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設置公用templates和公用static：

mysite/mysite/settings.py

TEMPLATES = [

??? {

??????? 'BACKEND': 'django.template.backends.django.DjangoTemplates',

??????? 'DIRS': [os.path.join(BASE_DIR, 'templates')],

??????? 'APP_DIRS': True,

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STATIC_URL = '/static/'

STATICFILES_DIRS = [

??? os.path.join(BASE_DIR, 'static'),

]

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>>> from django.template import Template,Context

>>> t = Template('My name is {{ name }}')

>>> c = Context({'name':'jowin'})?? #context可以是 dict、屬性、方法、tuple|list

>>> t.render(c)

'My name is jowin'

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>>> t = Template('my name is {{ name }}')

>>> d = {'name':'jowin'}

>>> c = Context(d)

>>> t.render(c)

'my name is jowin'

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>>> t = Template('my name is {{ user.name }}')?? #變量查找，dict、attr、method、list、tuple

>>> class Person:

...???? def __init__(self,name):

...???????????? self.name = name

...

>>> user = Person('jowin')

>>> user.name

'jowin'

>>> c = Context({'user':user})

>>> t.render(c)

'my name is jowin'

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>>> t = Template('my name is {{ user.name }}')

>>> class Person:

...???? def name(self):

...???????????? return 'jowin'

...

>>> user = Person()

>>> user.name()

'jowin'

>>> c = Context({'user':user})

>>> t.render(c)

'my name is jowin'

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模板引擎支持循環、判斷、過濾器：

for：

{% for person in person_list %}

<li> {{ person.name }} </li>

{% endfor %}

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if：

{% if max > 10 %}

<li>max value is {{ max }} </li>

{% else %}

<li>max value is 10 </li>

{% endif %}

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過濾器：

{{ now | date:"F j,Y" }}

{{ name | length }}

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view中使用template：

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render源碼，from django.shortcuts import render：

def render(request, template_name, context=None, content_type=None, status=None, using=None):

??? """

??? Returns a HttpResponse whose content is filled with the result of calling

??? django.template.loader.render_to_string() with the passed arguments.

??? """

??? content = loader.render_to_string(template_name, context, request, using=using)

??? return HttpResponse(content, content_type, status)

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另，render_to_response()，老版本1.6用；

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mysite/polls/views.py

from django.http import HttpResponse

from .models import Question

from django.template import loader

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# def index(request):

#???? latest_question_list = Question.objects.order_by('-pub_date')[:4]

#???? template = loader.get_template('polls/index.html')

#???? context = {'latest_question_list': latest_question_list}

#???? # output = ', '.join([q.question_text for q in latest_question_list])

#???? return HttpResponse(template.render(context))?? #方1

def index(request):

??? latest_question_list = Question.objects.order_by('-pub_date')[:4]

??? context = {'latest_question_list': latest_question_list}

??? return render(request, 'polls/index.html', context)?? #方2

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mysite/polls/templates/polls/index.html

<img src="/static/django.png">?? #mysite/polls/static/django.png

{% if latest_question_list %}

??? <ul>

??????? {% for question in latest_question_list %}

??????? <li><a href="/polls/{{ question.id }}/">{{ question.question_text }}</a></li>

??????? {% endfor %}

??? </ul>

{% endif %}

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(webproject) C:\webproject\mysite>python manage.py runserver

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去掉url和static硬編碼：

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mysite/polls/templates/polls/index.html

{% load static %}

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<img src="{% static 'django.png' %}">

{% if latest_question_list %}

??? <ul>

??????? {% for question in latest_question_list %}

??????? <!--<li><a href="/polls/{{ question.id }}/">{{ question.question_text }}</a></li>-->

??????? <li><a href="{% url 'detail' question.id %}">{{ question.question_text }}</a></li>

??????? {% endfor %}

??? </ul>

{% endif %}

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注：

{% url 'detail' question.id %}?? #app的urls.py中定義的name有關；app namespace改后，'detail'改為'polls:detail'；

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url反解析：

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正解析，url-->view；

反解析，view-->url；

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>>> from django.shortcuts import reverse

>>> reverse('detail',kwargs={'question_id':1})

'/polls/1/'

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另，reverse_lazy()，為解決循環依賴；

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url命名空間：

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app namespace和instance namespace：

通常使用app namespace；

若app有多個include，使用instance namespace；

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app namespace：

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mysite/polls/urls.py?? #方1，建議使用，在app_name/urls.py中定義

app_name = 'polls'

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mysite/mysite/urls.py

url(r'^polls/', include('polls.urls', app_name='polls')),?? #方2，在項目下定義mysite/mysite/urls.py

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instance namespace：

instance級別，名稱不可以重復；

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mysite/mysite/urls.py

url(r'^polls/', include('polls.urls', namespace='polls')),

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form處理：

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mysite/polls/templates/polls/detail.html

<h2>{{ question.question_text }}</h2>

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{% if error_message %}

??? <P><strong>{{ error_message }}</strong></P>

{% endif %}

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<form action="{% url 'polls:vote' question.id %}">

{% csrf_token %}

??? {% for choice in question.choice_set.all %}

??????? <input type="radio" name="choice" id="choice{{ forloop.counter }}" value="{{ choice.id }}" />

??????? <label for="choice{{ forloop.counter }}">{{ choice.choice_text }}</label><br />

??? {% endfor %}

? ??<input type="submit" value="Vote" />

</form>

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mysite/polls/views.py

from django.shortcuts import render, get_object_or_404, reverse

from django.http import HttpResponse, HttpResponseRedirect

from .models import Question, Choice

from django.template import loader

# from django.core.urlresolvers import reverse

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# def index(request):

#???? latest_question_list = Question.objects.order_by('-pub_date')[:4]

#???? template = loader.get_template('polls/index.html')

#???? context = {'latest_question_list': latest_question_list}

#???? # output = ', '.join([q.question_text for q in latest_question_list])

#???? return HttpResponse(template.render(context))

def index(request):

??? latest_question_list = Question.objects.order_by('-pub_date')[:4]

??? context = {'latest_question_list': latest_question_list}

??? return render(request, 'polls/index.html', context)

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def detail(request, question_id):

??? # try:

??? #???? question = Question.objects.get(id=question_id)

??? # except Question.DoesNotExist:

??? #???? return HttpResponse('Not Found', status=404)

??? question = get_object_or_404(Question, pk=question_id)

??? return render(request, 'polls/detail.html', {'question': question})

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def results(request, question_id):

??? question = get_object_or_404(Question, pk=question_id)

??? return render(request, 'polls/results.html', {'question': question})

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def vote(request, question_id):

??? question = get_object_or_404(Question, pk=question_id)

??? print(request)

??? if request.method == 'POST':

??????? choice_id = request.POST.get('choice', 0)

??????? try:

??????????? selected_choice = question.choice_set.get(pk=choice_id)

??????? except Choice.DoesNotExist:

??????????? return render(request, 'polls/detail.html', {

?????????? ?????'question': question, 'error_message': 'You did not select a choice',

??????????? })

??????? else:

??????????? selected_choice.votes += 1

??????????? selected_choice.save()

??????????? return HttpResponseRedirect(reverse('polls:results', args=(question.id,)))

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mysite/polls/templates/polls/results.html

<h2>{{ question.question_text }}</h2>

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<ul>

??? {% for choice in question.choice_set.all %}

??? <li>{{ choice.choice_text }} -- {{ choice.votes }} vote{{ choice.votes|pluralize }}</li>

??? {% endfor %}

</ul>

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<a href="{% url 'polls:detail' question.id %}">Vote again?</a>

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項目中使用：

pip install pymysql

pip install pillow?? #ImageField依賴

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1、? 數據庫使用mysql：

項目目錄的__init__.py中

import pymysql

pymysql.install_as_MySQLdb()

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DATABASES = {

? 'default': {

????? 'ENGINE': 'django.db.backends.mysql',

????? 'NAME': 'mxonline',

????? 'USER': 'mxonline',

????? 'PASSWORD': '123456',

????? 'HOST': '192.168.88.222',

????? 'PORT': 3306

? }

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2、apps目錄下統一放app：

右鍵apps-->Mark directory as-->Source Root?? #解決編輯器查找，import時可在apps中找

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import sys

sys.path.insert(0, os.path.join(BASE_DIR, 'apps'))?? #解決命令行環境查找

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