Django快速开发投票系统

使用Django搭建简单的投票系统：这个是官网的教程：https://docs.djangoproject.com/en/2.0/intro/tutorial01/

在Run manage.py Task中新建app：startapp polls
为了管理方便，我们新建apps文件夹，并将polls文件夹拖到apps中
第1部分：构建模型
新建polls的model

from django.db import models

# Create your models here.
class Question(models.Model):
question_text =models.CharField(max_length=200,verbose_name=u"问题内容")
pub_date = models.DateTimeField(verbose_name=u"发表时间")

class Meta:
verbose_name = "问题"
verbose_name_plural = verbose_name
def __str__(self):
return self.question_text

class Choice(models.Model):
question = models.ForeignKey(Question,verbose_name=u"问题内容")
choice_text = models.CharField(max_length=200,verbose_name=u"选项内容")
votes = models.IntegerField(default=0,verbose_name=u"投票")

class Meta:
verbose_name = "选择"
verbose_name_plural = verbose_name
def __str__(self):
return self.choice_text

然后通过命令python manage.py makemigrations python manage.py migrate进行迁移
我们也可以通过python manage.py sqlmigrate查看迁移过程中执行的原始sql语句

BEGIN;
--
-- Create model Choice
--
CREATE TABLE `polls_choice` (`id` integer AUTO_INCREMENT NOT NULL PRIMARY KEY, `choice_text` varchar(200) NOT NULL, `votes` integer NOT NULL);
--
-- Create model Question
--
CREATE TABLE `polls_question` (`id` integer AUTO_INCREMENT NOT NULL PRIMARY KEY, `question_text` varchar(200) NOT NULL, `pub_date` datetime(6) NOT NULL);
--
-- Add field question to choice
--
ALTER TABLE `polls_choice` ADD COLUMN `question_id` integer NOT NULL;
ALTER TABLE `polls_choice` ALTER COLUMN `question_id` DROP DEFAULT;
CREATE INDEX `polls_choice_7aa0f6ee` ON `polls_choice` (`question_id`);
ALTER TABLE `polls_choice` ADD CONSTRAINT `polls_choice_question_id_c5b4b260_fk_polls_question_id` FOREIGN KEY (`question_id`) REFERENCES `polls_question` (`id`);
COMMIT;
Following files were affected

请注意几点：
1：表名是自动生成的，由app的名字（polls）和模型名字的小写字母组合而成 —— question和choice
2：主键（id）是自动添加的。（你也可以重写这个行为。)
3：按照惯例，Django会在外键的字段名后面添加 "_id"。（是的，你依然可以重写这个行为。）

第二部分：使用xadmin搭建后台系统
在polls中新建adminx.py文件

import xadmin
from xadmin import views
from xadmin.plugins.auth import UserAdmin

from .models import Question,Choice

class ChoiceInline(object):
model = Choice
extra = 0

class QuestionAdmin(object):
list_display = ['question_text', 'pub_date'] #自定义显示这两个字段
search_fields = ['question_text', 'pub_date'] #可以搜索的字段
list_filter = ['question_text', 'pub_date']
ordering = ['-pub_date',] ##按照倒序排列
inlines = [ChoiceInline]
xadmin.site.register(Question,QuestionAdmin) #向Xadmin注册Question

 图1：管理系统图

 图2:问题与选项图

在图1中，后台系统中显示了投票问题，包括问题内容和发表时间。右上角可以新增内容，上面还有搜索框和过滤器

在图2中，在每个问题中可以选择选项内容

第三部分：视图和模板

from django.shortcuts import render
from django.http import HttpResponse,Http404
from .models import Question,Choice
# Create your views here.

from django.shortcuts import get_object_or_404, render
from django.http import HttpResponseRedirect
from django.core.urlresolvers import reverse
from django.views import generic

from .models import Choice, Question


class IndexView(generic.ListView):
template_name = 'polls/index.html'
context_object_name = 'latest_question_list'

def get_queryset(self):
"""Return the last five published questions."""
return Question.objects.order_by('-pub_date')[:5] #按照时间从小到大排序，取前5个


class DetailView(generic.DetailView):
model = Question
template_name = 'polls/detail.html'


class ResultsView(generic.DetailView):
model = Question
template_name = 'polls/results.html'


def vote(request, question_id):
p = get_object_or_404(Question, pk=question_id)
try:
selected_choice = p.choice_set.get(pk=request.POST['choice'])
except (KeyError, Choice.DoesNotExist):
# Redisplay the question voting form.
return render(request, 'polls/detail.html', {
'question': p,
'error_message': "You didn't select a choice.",
})
else:
selected_choice.votes += 1
selected_choice.save()
# Always return an HttpResponseRedirect after successfully dealing
# with POST data. This prevents data from being posted twice if a
# user hits the Back button.
return HttpResponseRedirect(reverse('polls:results', args=(p.id,)))

urlpatterns = [
url(r'^$', views.IndexView.as_view(), name='index'),
url(r'^(?P<pk>[0-9]+)/$', views.DetailView.as_view(), name='detail'),
url(r'^(?P<pk>[0-9]+)/results/$', views.ResultsView.as_view(), name='results'),
url(r'^(?P<question_id>[0-9]+)/vote/$', views.vote, name='vote'),
]

第四部分：表单

1:index.html   ---> 显示全部问题

{% if latest_question_list %}
    <ul>
    {% for question in latest_question_list %}
        <li><a href="/polls/{{ question.id }}/">{{ question.question_text }}</a></li>
    {% endfor %}
    </ul>
{% else %}
    <p>No polls are available.</p>
{% endif %}

2:detail.html ---> 问题详情页

<h1>{{ question.question_text }}</h1> 

{% if error_message %}<p><strong>{{ error_message }}</strong></p>{% endif %}

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

3：results.html ---> 投票结果页

<h1>{{ question.question_text }}</h1>

<ul>
{% for choice in question.choice_set.all %}
    <li>{{ choice.choice_text }} -- {{ choice.votes }} vote{{ choice.votes|pluralize }}</li>
{% endfor %}
</ul>

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

第五部分：结果展示

最终工程截图：

结果展示：

                      图3：投票问题

                   图4：问题选项

                图5：投票结果