Django Notes-Database operations (many-to-many relationships)

1. Project structure

2. Key code:

data6.settings.py

Installed_apps = (    'Django.contrib.admin',    'Django.contrib.auth',    'Django.contrib.contenttypes',    'django.contrib.sessions',    'django.contrib.messages',    'Django.contrib.staticfiles',    'Blog',) DATABASES= {    'default': {        'ENGINE':'Django.db.backends.mysql',        'NAME':'data6',        'USER':'Root',        'PASSWORD':'passwd',        'PORT':'3306',        'HOST':'localhost',    }}

View Code

blog.models.py

 fromDjango.dbImportModelsclassAuthor (models. Model): Name= Models. Charfield (max_length=30)        def __unicode__(self):returnSelf.nameclassBook (models. Model): Name= Models. Charfield (max_length=30) Authors=models. Manytomanyfield (Author)def __unicode__(self):returnSelf.name

View Code

3. Automatically generated data sheet

4. What Django does with the shell:

First, import the objects created in the models :

>>> from blog.models import Author,book

Add author:

>>> Author.objects.create (name= ' Tom01 ')

<Author:Tom01>

>>> Author.objects.create (name= ' Tom02 ')

<Author:Tom02>

>>> Author.objects.create (name= ' Tom03 ')

<Author:Tom03>

>>> Author.objects.create (name= ' Tom04 ')

<Author:Tom04>

To view the generated author:

>>> authors = Author.objects.all ()

>>> Authors

[<author:tom01>, <author:tom02>, <author:tom03>, <author:tom04>]

Add a book Python Book1

>>> B1 = Book ()

>>> b1.name = ' Pyhon Book1 '

>>> B1.save ()

Get an author

>>> tom2 = Author.objects.get (name__exact= ' Tom02 ')

>>> Tom2

<Author:Tom02>

Add author for Python Book1

>>> B1.authors.add (TOM2)

>>> B1.authors.add (authors[3])

the author of B1

>>> B1.authors.all ()

[<author:tom02>, <author:tom04>]

>>> B1.authors.add (authors[2])

Remove an author

>>> B1.authors.remove (authors[3])

>>> B1.authors.all ()

[<author:tom02>]

>>> B1.authors.add (Authors[0])

>>> B1.authors.all ()

[<author:tom01>, <author:tom02>]

>>> b1.authors.filter (name__exact= ' Carl ')

[]

See tom2 have those books

>>> Tom2.book_set.all ()

[<book:pyhon Book1>]

Add a book to tom2

>>> tom2.book_set.create (name= "Java")

<Book:java>

>>> Tom2.book_set.all ()

[<book:pyhon Book1>, <book:java>]

Look at all those books.

>>> books = Book.objects.all ()

>>> Books

[<book:pyhon Book1>, <book:java>]

Get rid of a book

>>> Tom2.book_set.remove (Books[0])

>>> Tom2.book_set.all ()

[<book:java>]

Django Notes-Database operations (many-to-many relationships)