Django Drops

1.Django Intro

Django Archite

2.Django Install

(1) PIP安装

sudo apt-get isntall python-pip
sudo pip install Django

(2) 源代码安装

/usr/local/share/Django/Django-1.8.3.tar.gz
Django-1.8.3
├── AUTHORS
├── build
├── dist
├── django
├── Django.egg-info
├── docs
├── extras
├── INSTALL
├── LICENSE
├── MANIFEST.in
├── PKG-INFO
├── README.rst
├── scripts
├── setup.cfg
├── setup.py
└── tests

sudo python setup.py install

3.Django Project

(1) 创建项目

root@kallen:Django#django-admin startproject MyProj
root@kallen:Django# tree MyProj/
MyProj/
├── manage.py
└── MyProj
    ├── __init__.py
    ├── settings.py
    ├── urls.py
    └── wsgi.py

_init_.py：
Django项目是Python包。这个文件是用来告诉Python这个文件夹当做一个包。在Python术语中。包是一组模块的集合，主要用来把类似的文件分组，防止出现命名冲突。

manage.py：
这个脚本用来管理你的项目，你能够把它看做是你项目的的django-admin.py版本号，事实上，manage.py和django-admin.py是共用同样的后台代码。

settings.py：
这是Django项目的主要配置文件，在这个文件中面，你能够详细说明非常多选项，包括数据库设置、网页语言、须要turn
on的Django功能。

urls.py：
这是另外一个配置文件。你能够把它看做是介于URLS和用来处理它们的Python方法之间的匹配;

(2) 创建应用

root@kallen:Django#python manage.py startapp jobs
└── MyProj
    ├── jobs
    │   ├── admin.py
    │   ├── __init__.py
    │   ├── migrations
    │   │   └── __init__.py
    │   ├── models.py
    │   ├── tests.py
    │   └── views.py
    ├── manage.py
    └── MyProj

(3) 创建实体类

from django.db import models
class Job(models.Model):
    pub_date = models.DateField()
    job_title = models.CharField(max_length=50)
    job_description = models.TextField()
    location = models.ForeignKey(Location)
    def __str__(self):
        return "%s (%s)" % (self.job_title, self.location)

(4) 查看数据库模式

root@kallen:/home/kallen/Python/Django/MyProj# python manage.py sql jobs
BEGIN;
CREATE TABLE `jobs_location` (
    `id` integer AUTO_INCREMENT NOT NULL PRIMARY KEY,
    `city` varchar(50)NOT NULL,
    `state` varchar(50),
    `country` varchar(50)NOT NULL
);
CREATE TABLE `jobs_job` (
    `id` integer AUTO_INCREMENT NOT NULL PRIMARY KEY,
    `pub_date` date NOT NULL,
    `job_title` varchar(50)NOT NULL,
    `job_description` longtext NOT NULL,
    `location_id` integerNOT NULL
);
ALTER TABLE `jobs_job` ADD CONSTRAINT `location_id_refs_id_35f2feb6` 
FOREIGN KEY (`location_id`) REFERENCES `jobs_location` (`id`);
COMMIT;

【常见错误】

$ python manage.py sql jobs
CommandError: App 'jobs' has migrations. Only the sqlmigrate and sqlflush commands
can be used when an app has migrations.

【解决的方法】　删除jobs下的migrations就能够了。

(5) 检查数据库模式

root@kallen:/home/kallen/Python/Django/MyProj#python manage.py validate
/usr/local/lib/python2.7/dist-packages/Django-1.8.3-py2.7.egg/django/core/
management/commands/validate.py:15: RemovedInDjango19Warning:"validate" has 
been deprecated in favor of"check".RemovedInDjango19Warning)
System check identified no issues (0 silenced).
root@kallen:/home/kallen/Python/Django/MyProj#python manage.py makemigrations
Migrations for 'jobs':
0001_initial.py:
- Create model Job
- Create model Location
- Add field location to job
root@kallen:/home/kallen/Python/Django/MyProj#python manage.py migrate
Operations to perform:
  Synchronize unmigrated apps: staticfiles, messages
  Apply all migrations: admin, contenttypes, jobs, auth, sessions
Synchronizing apps without migrations:
  Creating tables...
    Running deferred SQL...
  Installing custom SQL...
Running migrations:
  Rendering model states... DONE
  Applying jobs.0001_initial... OK

(6) 启动測试服务器

root@kallen:/home/kallen/Python/Django/MyProj#python manage.py runserver
Performing system checks...
System check identified no issues (0 silenced).
You have unapplied migrations; your app may not work properly until they are applied.
Run 'python manage.py migrate' to apply them.
August 14,2015-05:55:23
Django version 1.8.3, using settings 'MyProj.settings'
Starting development server at http://127.0.0.1:8000/
Quit the server with CONTROL-C.

(7) 后台管理

root@kallen:/home/kallen/Python/Django/MyProj#python manage.py syncdb

訪问url: http://127.0.0.1:8000/admin

(8) 注冊模型

from django.contrib issmport admin
# Register your models here.

# Register my models of job for mapping 
# utility class Location & Job.
# Kallen Ding, Agu 17 2015

from .models import Location, Job 

admin.site.register(Location)
admin.site.register(Job)

4.Django QuerySet

(1)条件查询

条件选取querySet的时候， filter表示 =，exclude表示 !=
querySet.distinct()

 __exact 精确等于 like 'aaa'
__iexact 精确等于 忽略大写和小写 ilike 'aaa'
__contains 包括 like '%aaa%'
__icontains 包括 忽略大写和小写 ilike '%aaa%'，可是对于sqlite来说，contains的作用效果等同于icontains。 
__gt 大于 
__gte 大于等于 
__lt 小于 
__lte 小于等于 
__in 存在于一个list范围内 
__startswith 以...开头 
__istartswith 以...开头 忽略大写和小写 
__endswith 以...结尾 
__iendswith 以...结尾。忽略大写和小写 
__range 在...范围内 
__year 日期字段的年份 
__month 日期字段的月份 
__day 日期字段的日 
__isnull=True/False

5.Django Form

在html页面中，django会自己主动输出form表单。而无需自定义，详情请參考 The Forms API.

<form id="your-profile" action="/contact" method="post">
<table class="form-table">

(1) 在 `<p>` 中显示表单

{{ form.as_p }}

实际输出的HTML例如以下：

<p><label for="id_subject">Subject:</label> 
<input id="id_subject" type="text" name="subject" maxlength="100"/>
</p>
<p><label for="id_message">Message:</label> 
<input type="text" name="message" id="id_message"/>
</p>
<p><label for="id_sender">Sender:</label> 
<input type="email" name="sender" id="id_sender"/>
</p>
<p><label for="id_cc_myself">Cc myself:</label> 
<input type="checkbox" name="cc_myself" id="id_cc_myself"/>
</p>

(2) 在 `<ul>` 中显示表单

{{ form.as_ul }}

实际输出的HTML例如以下：

<li><label for="id_subject">Subject:</label> 
<input id="id_subject" type="text" name="subject" maxlength="100" />
</li>
<li><label for="id_message">Message:</label> 
<input type="text" name="message" id="id_message"/></li>
<li><label for="id_sender">Sender:</label> 
<input type="email" name="sender" id="id_sender"/>
</li>
<li><label for="id_cc_myself">Cc myself:</label> 
<input type="checkbox" name="cc_myself" id="id_cc_myself"/>
</li>

(3) 在 `<table>` 中显示表单

{{ form.as_table }}

实际输出的HTML例如以下：

<tr><th><label for="id_subject">Subject:</label></th><td><input id="id_subject" type="text" name="subject" maxlength="100" /></td></tr>
<tr><th><label for="id_message">Message:</label></th><td><input type="text" name="message" id="id_message" /></td></tr>
<tr><th><label for="id_sender">Sender:</label></th><td><input type="email" name="sender" id="id_sender" /></td></tr>
<tr><th><label for="id_cc_myself">Cc myself:</label></th><td><input type="checkbox" name="cc_myself" id="id_cc_myself" /></td></tr>

(4) 以循环形式显示表单

{% for field in form %}               
    {{ field.label_tag }}:{{ field }}
    {{ field.errors }}
{% endfor %}

为了自定义输出表单的样式，能够在Form对象中给组件加入 atts 属性：

attrs={
    'class': 'form-control',
    'placeholder': 'Username'
}

注冊按钮及Button：

</table>
<p class="submit">
<input type="submit" name="submit" id="submit"class="button-primary" value="注冊信息"/>
</p>
</form>

6.Django Request

request.META

一个Python字典。包括了全部本次HTTP请求的Header信息，比方用户IP地址和用户Agent（一般是浏览器的名称和版本号号）。

注意。Header信息的完整列表取决于用户所发送的Header信息和服务器端设置的Header信息。这个字典中几个常见的键值有：

HTTP_REFERRER 进站前链接网页，假设有
HTTP_USER_AGENT 览器的user-agent字符串。假设有的话。
比如：

 "Mozilla/5.0 (X11; U; Linux i686; fr-FR; rv:1.8.1.17) Gecko/20080829 Firefox/2.0.0.17".
REMOTE_ADDR

客户端IP。如：”12.345.67.89” 。

(假设申请是经过代理服务器的话，那么它可能是以逗号切割的多个IP地址。如：”12.345.67.89,23.456.78.90”)

[注意]

由于 request.META 是一个普通的Python字典，因此当你试图訪问一个不存在的键时，会触发一个 KeyError异常;

（HTTP header信息是由用户的浏览器所提交的、不应该给予信任的”额外”数据，因此你总是应该好好设计你的应用以便当一个特定的Header数据不存在时，给出一个优雅的回应）

你应该用 try/except 语句，或者用Python字典的 get() 方法来处理这些“可能不存在的键”：

# BAD!
def ua_display_bad(request):
    ua = request.META['HTTP_USER_AGENT']
    # Might raise KeyError!
    return HttpResponse("Your browser is%s" % ua)

# GOOD (VERSION 1)
def ua_display_good1(request):
    try:
        ua = request.META['HTTP_USER_AGENT']
    exceptKeyError:
        ua ='unknown'
    return HttpResponse("Your browser is%s" % ua)

# GOOD (VERSION 2)
def ua_display_good2(request):
    ua = request.META.get('HTTP_USER_AGENT','unknown')
    return HttpResponse("Your browser is%s" % ua)

7.Static & Media

from django.conf import settings
if settings.DEBUG:
    urlpatterns += patterns('',
        url(r'^upload/(?P<path>.*)$', 
        'django.views.static.serve',
        {'document_root':settings.MEDIA_ROOT}),
    )

8.Migrations

在1.6之前, Django仅仅支持加入新的model到数据库, 而无法编辑或改动已经存在的model.
Django 1.7 为我们带来了三个新命令:

migrate: 用于执行迁移动作
makemigrations: 基于当前的model创建新的迁移策略文件
sqlmigrate: 显示迁移的SQL语句

值得注意的是,migration是基于App的, 因此, 我们能够针对某些app不启用migration功能.
migrations的使用非常easy: 改动model, 比方添加field, 然后执行

    python manager.py makemigrations

你的mmodel会被扫描, 然后与之前的版本号作比較, 在app的migrations文件夹下生成本次迁移文件.
我们建议查看一下该迁移文件, 确保没有问题. 然后执行:

    python manager.py migrate

migrate命令会进行比較, 并应用该迁移.

9.Django FAQ

(1) 导入MySQL错误

django.core.exceptions.ImproperlyConfigured: Error loading MySQLdb module

【解决的方法】安装mysql-python模块

安装步骤：

sudo apt-get install python-setuptools
sudo apt-get install libmysqld-dev
sudo apt-get install libmysqlclient-dev 
sudo apt-get install python-dev
sudo easy_install mysql-python

測试下：在python交互式窗体，import MySQLdb 试试，不报错的话，就证明安装好了。

(2) 导入model对象出错

>>> from jobs.models import Job
django.core.exceptions.ImproperlyConfigured: Requested setting DEFAULT_INDEX_TABLESPACE, but settings are not configured. You must either define the environment variable DJANGO_SETTINGS_MODULE or call settings.configure() before accessing settings.

【解决的方法】

>>>from django.conf import settings  
>>> settings.configure()

(3) CSRF Verification Failed

Forbidden (403)
CSRF verification failed. Request aborted.
Help
Reason given for failure:
    CSRF token missing or incorrect.
In general, this can occur when there is a genuine Cross Site Request Forgery, or when Django's CSRF mechanism has not been used correctly. For POST forms, you need to ensure:
Your browser is accepting cookies.
The view function passes a request to the template's render method.
In the template, there is a {% csrf_token %} template tag inside each POST form that targets an internal URL.
If you are not using CsrfViewMiddleware, then you must use csrf_protect on any views that use the csrf_token template tag, as well as those that accept the POST data.
You're seeing the help section of this page because you have DEBUG =Truein your Django settings file. Change that to False, and only the initial error message will be displayed.
You can customize this page using the CSRF_FAILURE_VIEW setting.

【解决的方法】

第一种：在表单里加上{% csrf_token %}即可了；

另外一种：在Settings里的MIDDLEWARE_CLASSES添加配置：

'django.middleware.csrf.CsrfViewMiddleware',
'django.middleware.csrf.CsrfResponseMiddleware',

方法二不可行：

ImportError: Module "django.middleware.csrf" does not define a "CsrfResponseMiddleware" attribute/class

在測试环境下仅仅须要将这两行凝视即可；

(4) Exception

Exception happened during processing of request from ('127.0.0.1', 59311)
Traceback (most recent call last):
  File "/usr/lib/python2.7/SocketServer.py", line 593, in process_request_thread
Exception happened during processing of request from ('127.0.0.1', 59312)
Traceback (most recent call last):
  File "/usr/lib/python2.7/SocketServer.py", line 593, in process_request_thread

(5) IPAddressField

arigue.Server.ipaddr: (fields.W900) IPAddressField has been deprecated. Support forit(except in historical migrations) will be removed in Django 1.9.
    HINT: Use GenericIPAddressField instead.

【解决的方法】推荐使用 GenericIPAddressField()

(6) Forbidden

CSRF verification failed. Request aborted.

Help
Reason given for failure:
    CSRF token missing or incorrect.

In general, this can occur when there is a genuine Cross Site Request Forgery, or when Django's CSRF mechanism has not been used correctly. For POST forms, you need to ensure:
Your browser is accepting cookies.
The view function passes a request to the template's render method.
In the template, there is a {% csrf_token %} template tag inside each POST form that targets an internal URL.
If you are not using CsrfViewMiddleware, then you must use csrf_protect on any views that use the csrf_token template tag, as well as those that accept the POST data.
You're seeing the help section of this page because you have DEBUG = True in your Django settings file. Change that to False, and only the initial error message will be displayed.
You can customize this page using the CSRF_FAILURE_VIEW setting.

(7) AppRegistryNotReady

django.core.exceptions.AppRegistryNotReady: Models aren't loaded yet.

这个异常是在windows上使django-xadmin时产生的，一直没解决。望各位知道的Pythoner回复。

【參考文章】

http://queengina.com/2014/10/15/Django%E7%B3%BB%E5%88%97%EF%BC%88%E4%BA%8C%EF%BC%89/

http://stackoverflow.com/questions/6315960/djangos-querydict-bizarre-behavior-bunches-post-dictionary-into-a-single-key

posted @ 2018-04-06 17:43 llguanli 阅读(262) 评论(0) 编辑收藏举报

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Django Drops

1.Django Intro

2.Django Install

(1) PIP安装

(2) 源代码安装

3.Django Project

(1) 创建项目

(2) 创建应用

(3) 创建实体类

(4) 查看数据库模式

(5) 检查数据库模式

(6) 启动測试服务器

(7) 后台管理

(8) 注冊模型

4.Django QuerySet

(1)条件查询

5.Django Form

(1) 在 <p> 中显示表单

(2) 在 <ul> 中显示表单

(3) 在 <table> 中显示表单

(4) 以循环形式显示表单

6.Django Request

request.META

7.Static & Media

8.Migrations

9.Django FAQ

(1) 导入MySQL错误

(2) 导入model对象出错

(3) CSRF Verification Failed

(4) Exception

(5) IPAddressField

(6) Forbidden

(7) AppRegistryNotReady

(1) 在 `<p>` 中显示表单

(2) 在 `<ul>` 中显示表单

(3) 在 `<table>` 中显示表单