創(chuàng)建模型

下面是創(chuàng)建一個 Dreamreal 模型實例 ?

from django.db import models

class Dreamreal(models.Model):

   website = models.CharField(max_length = 50)
   mail = models.CharField(max_length = 50)
   name = models.CharField(max_length = 50)
   phonenumber = models.IntegerField()

   class Meta:
      db_table = "dreamreal"

Meta類與db_table屬性可以讓我們定義的實際表或集合名稱。Django會自動命名表或集合：myapp_modelName. 這個類將強制表的名稱。

在 django.db.models 更多的字段的類型，你可以了解更多關(guān)于他們的URL：

https://docs.djangoproject.com/en/1.5/ref/models/fields/

在創(chuàng)建模型后需要 Django 產(chǎn)生實際的數(shù)據(jù)庫 ?

$python manage.py syncdb 

操作數(shù)據(jù)(CRUD)

讓我們創(chuàng)建一個“crudops”的視圖，看看如何能夠在模型上做的CRUD操作。 現(xiàn)在 myapp/views.py 然后將看起來像 ?

myapp/views.py

from myapp.models import Dreamreal
from django.http import HttpResponse

def crudops(request):
   #Creating an entry
   
   dreamreal = Dreamreal(
      website = "www.polo.com", mail = "sorex@polo.com", 
      name = "sorex", phonenumber = "002376970"
   )
   
   dreamreal.save()
   
   #Read ALL entries
   objects = Dreamreal.objects.all()
   res ='Printing all Dreamreal entries in the DB : <br>'
   
   for elt in objects:
      res += elt.name+"<br>"
   
   #Read a specific entry:
   sorex = Dreamreal.objects.get(name = "sorex")
   res += 'Printing One entry <br>'
   res += sorex.name
   
   #Delete an entry
   res += '<br> Deleting an entry <br>'
   sorex.delete()
   
   #Update
   dreamreal = Dreamreal(
      website = "www.polo.com", mail = "sorex@polo.com", 
      name = "sorex", phonenumber = "002376970"
   )
   
   dreamreal.save()
   res += 'Updating entry<br>'
   
   dreamreal = Dreamreal.objects.get(name = 'sorex')
   dreamreal.name = 'thierry'
   dreamreal.save()
   
   return HttpResponse(res)

其他數(shù)據(jù)操作

讓我們來探討可以對模型做的其他操作。 需要注意的是 CRUD 操作都做對模型的實例，現(xiàn)在我們將直接表示模型類的工作。

from myapp.models import Dreamreal
from django.http import HttpResponse

def datamanipulation(request):
   res = ''
   
   #Filtering data:
   qs = Dreamreal.objects.filter(name = "paul")
   res += "Found : %s results<br>"%len(qs)
   
   #Ordering results
   qs = Dreamreal.objects.order_by("name")
   
   for elt in qs:
      res += elt.name + '<br>'
   
   return HttpResponse(res)

鏈接模型

Django ORM提供3種方式來鏈接模型 ?

我們將在這里看到的第一示例是一個一對多的關(guān)系。正如在上面的例子中看到的，一個公司可以有多個在線網(wǎng)站。定義這種關(guān)系是通過使用 django.db.models.ForeignKey 完成 -

myapp/models.py

from django.db import models

class Dreamreal(models.Model):
   website = models.CharField(max_length = 50)
   mail = models.CharField(max_length = 50)
   name = models.CharField(max_length = 50)
   phonenumber = models.IntegerField()
   online = models.ForeignKey('Online', default = 1)
   
   class Meta:
      db_table = "dreamreal"

class Online(models.Model):
      domain = models.CharField(max_length = 30)
   
   class Meta:
      db_table = "online"

讓我們來看看如何通過 manage.py shell 執(zhí)行所有工作 ?

首先讓我們來測試 Django shell創(chuàng)建一些公司(Dreamreal項)?

$python manage.py shell

>>> from myapp.models import Dreamreal, Online
>>> dr1 = Dreamreal()
>>> dr1.website = 'company1.com'
>>> dr1.name = 'company1'
>>> dr1.mail = 'contact@company1'
>>> dr1.phonenumber = '12345'
>>> dr1.save()
>>> dr2 = Dreamreal()
>>> dr1.website = 'company2.com'
>>> dr2.website = 'company2.com'
>>> dr2.name = 'company2'
>>> dr2.mail = 'contact@company2'
>>> dr2.phonenumber = '56789'
>>> dr2.save() 

>>> on1 = Online()
>>> on1.company = dr1
>>> on1.domain = "site1.com"
>>> on2 = Online()
>>> on2.company = dr1
>>> on2.domain = "site2.com"
>>> on3 = Online()
>>> on3.domain = "site3.com"
>>> dr2 = Dreamreal.objects.all()[2]
>>> on3.company = dr2
>>> on1.save()
>>> on2.save()
>>> on3.save() 

>>> on1.company.name 

>>> dr1.online_set.all() 

為了得到一個QuerySet，請注意，所有的操作方法，我們以前見過(filter, all, exclude, order_by....)

也可以訪問進(jìn)行過濾操作鏈接模型屬性，比方說，想獲得的所有在線域所在Dreamreal名稱包含“company”-

>>> Online.objects.filter(company__name__contains = 'company' 

注 - 那種查詢只支持SQL數(shù)據(jù)庫。 它不會對非關(guān)系數(shù)據(jù)庫工作，其中連接不存在，并有兩個“_”。

但是，這不是鏈接模型的唯一方法，也有OneToOneField，這保證了兩個對象之間的關(guān)系是唯一的鏈接關(guān)系。如果使用了OneToOneField在上面的例子中，這將意味著只有一個在線條目對應(yīng)于每個Dreamreal條目。