Python 18 Day

Posted 2020-08-08

Django

基本操作

1. 创建一个 Django 项目: django-admin startproject sitename
2. 创建一个 app: python manage.py startapp web
3. 运行: python manage.py runserver 127.0.0.1:8000

Django 处理请求流程

1. 在 settings.py 中添加创建的 app
2. urls.py 映射 URLpattern: URLpattern --> app.func
3. views.py 中 使用 render() 渲染模板 (templates) 并返回结果
4. 配置静态文件
   1. 在 django 项目中创建 static 作为静态文件夹
   2. 在 settings.py 中添加静态文件目录路径

   3. STATIC_URL = ‘/static/‘
      STATICFILES_DIRS = (
          os.path.join(BASE_DIR, ‘static‘),
      )

   4. 在模板中引用

   5. <script src="/static/xxx.js"></script>

Views and URLconfs

To design URLs for an application, you create a Python module called a URLconf. Like a table of contents for your app, it contains a simple mapping between URL patterns and your views.

urls.py

from django.conf.urls import url
from cmdb import views

urlpatterns = [
    url(r‘^index/‘, views.index), # mapping URL patterns and views
]

views.py

a view is responsible for doing some arbitrary logic, and then returning a response.

from django.shortcuts import HttpResponse

def index(request):
    return HttpResponse(‘hello world‘)

Templates

With Django’s template system, we can separate the design of the page from the Python code itself. A Django template is a string of text that is intended to separate the presentation of a document from its data. Usually, templates are used for producing HTML, but Django templates are equally capable of generating any text-based format.

• Any text surrounded by a pair of braces (e.g., {{ person_name }}) is a variable.
• Any text that’s surrounded by curly braces and percent signs (e.g., {% if ordered_warranty %}) is a template tag.
  • for tag:

  • {% for item in item_list %}
        <li>{{ item }}</li>
    {% endfor %}

  • if tag:

  • {% if ordered_warranty %}
        <p>Your warranty information will be included in the packaging.</p>
    {% else %}
        <p>You didn‘t order a warranty, so you‘re on your own when
        the products inevitably stop working.</p>
    {% endif %}

  • filter

  • <p>Thanks for placing an order from {{ company }}. It‘s scheduled to
    ship on {{ ship_date|date:"F j, Y" }}.</p>

    In this example, {{ ship_date|date:"F j, Y" }}, we’re passing the ship_date variable to the date filter, giving the date filter the argument "F j, Y".

Here is the most basic way you can use Django’s template system in Python code:

1. Create a Template object by providing the raw template code as a string.
2. Call the render() method of the Template object with a given set of variables (the context). This returns a fully rendered template as a string, with all of the variables and template tags evaluated according to the context.

3. from django.shortcuts import render
   
   USER_INPUT = {}
   
   def index(request):
       """get submit"""
       if (request.method == ‘post‘):
           user = request.POST.get(‘user‘, None) # None is default value
           email = request.POST.get(‘email‘, None)
           temp = {‘user‘: user, ‘email‘: email}
           USER_INPUT.append(temp)
   
       """
       template loading: t = template.Template(‘My name is {{ name }}.‘)
       context creation: c = template.Context({‘name‘: ‘Adrian‘})
       template rendering: t.render(c)
       HttpResponse creation
       """
       return render(request, ‘index.html‘, {‘data‘: USER_INPUT})

render()

Django provides a shortcut that lets you

1. load a template 加载模板

2. render it and return an HttpResponse 渲染

all in one line of code.

Models

Django’s database layer.

models.py

from django.db import models

# Create your models here.

class UserInfo(models.Model):
    user = models.CharField(max_length=32)
    email = models.CharField(max_length=32)

create databases:

python manage.py makemigrations

python manage.py migrate

509 garyyang:mysite_django$ python3 manage.py makemigrations
Migrations for ‘cmdb‘:
  cmdb/migrations/0001_initial.py:
    - Create model UserInfo
511 garyyang:mysite_django$ python3 manage.py migrate
Operations to perform:
  Apply all migrations: admin, auth, cmdb, contenttypes, sessions
Running migrations:
  Rendering model states... DONE
  Applying contenttypes.0001_initial... OK
  Applying auth.0001_initial... OK
  Applying admin.0001_initial... OK
  Applying admin.0002_logentry_remove_auto_add... OK
  Applying contenttypes.0002_remove_content_type_name... OK
  Applying auth.0002_alter_permission_name_max_length... OK
  Applying auth.0003_alter_user_email_max_length... OK
  Applying auth.0004_alter_user_username_opts... OK
  Applying auth.0005_alter_user_last_login_null... OK
  Applying auth.0006_require_contenttypes_0002... OK
  Applying auth.0007_alter_validators_add_error_messages... OK
  Applying auth.0008_alter_user_username_max_length... OK
  Applying cmdb.0001_initial... OK
  Applying sessions.0001_initial... OK