Django Drops

1.Django Intro

2.Django Install

(1) PIP安裝

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

(2) 源碼安裝

/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) 創建項目

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項目是Python包，這個文件是用來告訴Python這個文件夾當做一個包。在Python術語中，包是一組模塊的集合，主要用來把相似的文件分組，防止出現命名衝突。

manage.py：
這個腳本用來管理你的項目，你可以把它看做是你項目的的django-admin.py版本，其實，manage.py和django-admin.py是共用相同的後臺代碼。

settings.py：
這是Django項目的主要配置文件，在這個文件裏面，你可以具體說明很多選項，包括數據庫設置、網頁語言、需要turn
on的Django功能。

urls.py：
這是另外一個配置文件。你可以把它看做是介於URLS和用來處理它們的Python方法之間的匹配;

(2) 創建應用

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) 創建實體類

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) 查看數據庫模式

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;

【常見錯誤】

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

【解決辦法】　刪除jobs下的migrations就可以了；

(5) 檢查數據庫模式

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) 啓動測試服務器

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) 後臺管理

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

訪問url: http://127.0.0.1:8000/admin

(8) 註冊模型

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)條件查詢

條件選取querySet的時候， filter表示 =，exclude表示 !=
querySet.distinct()

 __exact 精確等於 like 'aaa'
__iexact 精確等於 忽略大小寫 ilike 'aaa'
__contains 包含 like '%aaa%'
__icontains 包含 忽略大小寫 ilike '%aaa%'，但是對於sqlite來說，contains的作用效果等同於icontains。 
__gt 大於 
__gte 大於等於 
__lt 小於 
__lte 小於等於 
__in 存在於一個list範圍內 
__startswith 以...開頭 
__istartswith 以...開頭 忽略大小寫 
__endswith 以...結尾 
__iendswith 以...結尾，忽略大小寫 
__range 在...範圍內 
__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頁面中，django會自動輸出form表單，而無需自己定義，詳情請參考 The Forms API.

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

(1) 在 `<p>` 中顯示錶單

{{ form.as_p }}

實際輸出的HTML如下：

<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>` 中顯示錶單

{{ form.as_ul }}

實際輸出的HTML如下：

<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>` 中顯示錶單

{{ form.as_table }}

實際輸出的HTML如下：

<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) 以循環形式顯示錶單

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

爲了自定義輸出表單的樣式，可以在Form對象中給組件添加 atts 屬性：

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

註冊按鈕及Button：

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

6.Django Request

request.META

一個Python字典，包含了所有本次HTTP請求的Header信息，比如用戶IP地址和用戶Agent（通常是瀏覽器的名稱和版本號）。

注意，Header信息的完整列表取決於用戶所發送的Header信息和服務器端設置的Header信息。這個字典中幾個常見的鍵值有：

HTTP_REFERRER 進站前鏈接網頁，如果有
HTTP_USER_AGENT 覽器的user-agent字符串，如果有的話。
例如：

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

客戶端IP，如：”12.345.67.89” 。

(如果申請是經過代理服務器的話，那麼它可能是以逗號分割的多個IP地址，如：”12.345.67.89,23.456.78.90”)

[注意]

因爲 request.META 是一個普通的Python字典，因此當你試圖訪問一個不存在的鍵時，會觸發一個 KeyError異常;

（HTTP header信息是由用戶的瀏覽器所提交的、不應該給予信任的”額外”數據，因此你總是應該好好設計你的應用以便當一個特定的Header數據不存在時，給出一個優雅的迴應）

你應該用 try/except 語句，或者用Python字典的 get() 方法來處理這些“可能不存在的鍵”：

# 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只支持添加新的model到數據庫, 而無法編輯或修改已經存在的model.
Django 1.7 爲我們帶來了三個新命令:

migrate: 用於執行遷移動作
makemigrations: 基於當前的model創建新的遷移策略文件
sqlmigrate: 顯示遷移的SQL語句

值得注意的是,migration是基於App的, 因此, 我們可以針對某些app不啓用migration功能.
migrations的使用非常簡單: 修改model, 比如增加field, 然後運行

    python manager.py makemigrations

你的mmodel會被掃描, 然後與之前的版本作比較, 在app的migrations目錄下生成本次遷移文件.
我們建議查看一下該遷移文件, 確保沒有問題. 然後運行:

    python manager.py migrate

migrate命令會進行比較, 並應用該遷移.

9.Django FAQ

(1) 導入MySQL錯誤

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

【解決辦法】安裝mysql-python模塊

安裝步驟：

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

測試下：在python交互式窗口，import MySQLdb 試試，不報錯的話，就證明安裝好了。

(2) 導入model對象出錯

>>> 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.

【解決辦法】

>>>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.

【解決辦法】

第一種：在表單里加上{% csrf_token %}就行了；

第二種：在Settings裏的MIDDLEWARE_CLASSES增加配置：

'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

在測試環境下只需要將這兩行註釋即可；

(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.

【解決辦法】推薦使用 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.

這個異常是在windows上使django-xadmin時產生的，一直沒解決，望各位知道的Pythoner回覆。

【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

1.Django Intro

2.Django Install

(1) PIP安裝

(2) 源碼安裝

3.Django Project

(1) 創建項目

(2) 創建應用

(3) 創建實體類

(4) 查看數據庫模式

(5) 檢查數據庫模式

(6) 啓動測試服務器

(7) 後臺管理

(8) 註冊模型

4.Django QuerySet

(1)條件查詢

5.Django Form

(1) 在 <p> 中顯示錶單

(2) 在 <ul> 中顯示錶單

(3) 在 <table> 中顯示錶單

(4) 以循環形式顯示錶單

6.Django Request

request.META

7.Static & Media

8.Migrations

9.Django FAQ

(1) 導入MySQL錯誤

(2) 導入model對象出錯

(3) CSRF Verification Failed

(4) Exception

(5) IPAddressField

(6) Forbidden

(7) AppRegistryNotReady

(1) 在 `<p>` 中顯示錶單

(2) 在 `<ul>` 中顯示錶單

(3) 在 `<table>` 中顯示錶單