$ django-admin startproject mysite
# 运行后，就会创建一个 mysite 文件夹，结构为：
​
########################
# mysite/
#     manage.py
#     mysite/
#         __init__.py
#         settings.py
#         urls.py
#         wsgi.py
########################

# start the Django development server,
python manage.py runserver

python manage.py runserver 0:8888

# polls/urls.py
from django.urls import path
from . import views
​
urlpatterns = [
    path('', views.index, name='index'),
]

# mysite/urls.py
from django.contrib import admin
from django.urls import include, path
​
urlpatterns = [
    path('polls/', include('polls.urls')),
    path('admin/', admin.site.urls),
]

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': "senti_weibo",
        'USER': 'root',         # 数据库用户名
        'PASSWORD': 'ws6226067',     # 密码
        'HOST': '47.92.253.60',    # 主机
        'PORT': '3306',         # 数据库默认使用的端口
    }
}

LANGUAGE_CODE = 'zh-hans'
​
TIME_ZONE = 'Asia/Shanghai'

INSTALLED_APPS = [
    'django.contrib.admin', # The admin site
    'django.contrib.auth', # An authentication system
    'django.contrib.contenttypes', # A framework for content types.
    'django.contrib.sessions', # A session framework.
    'django.contrib.messages', # A messaging framework.
    'django.contrib.staticfiles', # A framework for managing static files.
    'senti_weibo.apps.SentiWeiboConfig',
]

python manage.py migrate

from django.http import HttpResponse
from django.template import loader
​
from .models import Question
​
​
def index(request):
    latest_question_list = Question.objects.order_by('-pub_date')[:5]
    template = loader.get_template('polls/index.html')
    context = {
        'latest_question_list': latest_question_list,
    }
    return HttpResponse(template.render(context, request))

from django.shortcuts import render
​
from .models import Question
​
​
def index(request):
    latest_question_list = Question.objects.order_by('-pub_date')[:5]
    context = {'latest_question_list': latest_question_list}
    return render(request, 'polls/index.html', context)

from django.http import Http404
​
# 在找不到其所请求的内容的时候，返回 404 异常
raise Http404("Question does not exist")

from django.shortcuts import get_object_or_404, render
​
from .models import Question
# ...
def detail(request, question_id):
    question = get_object_or_404(Question, pk=question_id)
    return render(request, 'polls/detail.html', {'question': question})

# 导入 models 文件
from . import models
​
# 参考文档
# https://docs.djangoproject.com/en/2.1/ref/models/
# https://docs.djangoproject.com/en/2.1/topics/db/queries/
​
# 同步模型到数据库
python manage.py makemigrations # 针对 models 的更新生成 migrations
python manage.py migrate # 将 migrations 同步到数据库
​
# 插入数据
statistics = models.student(name="wansho", age=25, score=100)
statistics.save()
​
# 批量插入
sql1 = models.account(name="wansho", passwd="hehe") # new 一个插入对象
sql2 = models.account(name="love", passwd="123")
bulk_list = [sql1, sql2]
models.student.objects.bulk_create(bulk_list) # 返回 bulk_list
​
# 查找数据 
get：只返回一条元组，可直接编辑
filter：返回一个元组列表
# 官方文档：https://docs.djangoproject.com/en/2.1/topics/db/queries/
taskconf = models.taskconf.objects.filter(product_line = product_line, effective = True).exclude(source = "sample").exclude(idc__in = ["se-offline", "template", "ipad_page"]).exclude(module = "debug") # 返回一个集合
models.functions.objects.get(function = function, module = module) # 查找唯一数据
pd_olddata = pd.DataFrame(list(models.functions.objects.all().
       exclude(card_id = 0).values())) # 所有数据
# 注意，Django 接口返回的数据，要使用 .values() 遍历
>>> Blog.objects.filter(name__startswith='Beatles').values()
<QuerySet [{'id': 1, 'name': 'Beatles Blog', 'tagline': 'All the latest Beatles news.'}]>  # .values() 返回一个 list，其中元素是字典
​
* 改
    m = Model.objects.get(id=1)
    m.name = 'new_name'
    m.save()
    直接更新，filter 返回一个 list，get 只返回一条元组
    models.functions.objects.filter(module = module, 
                function = function).update(
                        pv = pv,
                        product_form = product_form,
                        cid = cid,
                        jiaotu_need = jiaotu_need,
                        jiaotu_coverage = jiaotu_coverage,
                        description = description)
​
* 删
    m = Model.objects.get(id=1)
    m.delete()
​
* Django 数据库初始化 Model 
null 是针对数据库而言，如果 null=True, 表示数据库的该字段可以为空，即在Null字段显示为YES。
blank 是针对表单的，如果 blank=True，表示你的表单填写该字段的时候可以不填，但是对数据库来说，没有任何影响
class deploydetail(models.Model): # deploydetail 为表名
    product_line = models.CharField(max_length=32, blank=True, null=False)
    statistics_time = models.DateTimeField()
​
* 获取所有数据，除去一些数据，并转成 pandas
pd.DataFrame(list(models.functions.objects.exclude(card_id = "0").values()))

#  This is the equivalent of SQL’s LIMIT and OFFSET clauses.
Entry.objects.all()[:5]

negative_sql = """
                select 
                    seged_weibo, label, id  
                from 
                    senti_weibo_train_data 
                where  
                    label = "__label__negative" and 
                    is_duplicated = "N" and 
                    length(seged_weibo) >= 15
                limit 5;
        """
negative_weibos = models.train_data.objects.raw(negative_sql)[: 3]
print(negative_weibos[0].label)

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

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

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

STATICFILES_DIRS = [
    os.path.join(BASE_DIR, "static"), # BASE_DIR 是与 manage.py 所在的文件夹
    '/var/www/static/',
]

{% load static %}
<link rel="stylesheet" href="{% static 'js/echarts.min.js' %}" >

# 1. 新建一个 project
django-admin.py startproject project-name
​
# 新建一个 app
python manage.py startapp bilibili_helper
​
# 2. 数据模型相关命令
python manage.py makemigrations app_name 
# 告诉 django, models 模型有所改动，对变动生成 migrations，本质上是将 models 转成 SQL
# 会在 app_name/migrations/ 下生成临时文件，例如 0001_initial.py，如果我们想要查看该命令到底把 models 转成了什么 SQL，可以使用 sqlmigrate 命令查看：
python manage.py sqlmigrate student 0001
​
python manage.py migrate
# 将 models.py 视图的变动同步到数据库，本质上是在 DBMS 上执行 SQL 
​
# 3. 调试运行单个 py 文件
python manage.py coverage # 在 Django 的根目录下
​
# 4. 设置端口号
python manage.py runserver 192.168.1.50:8080
​
# 5. 进入 django　的 shell 命令行
python manage.py shell 
​
# 创建管理员
python manage.py createsuperuser