How to Learn Python – Django- Getting Started (Design Model)

Model design

• Current project development is data-driven, and analyze the data needed to be stored in the project, then design the data table and structure, and then use the designed page to complete the CRUD of data
• Djangos built-in ORM framework does not require direct database programming. Instead, it defines model classes and uses model classes and objects to cruD data tables
• The steps for database development using Django are as follows:

1. Define model classes in models.py
2. The migration

3. Data CRUD through classes and objects

1. Define model classes

• The Model class is defined in the models.py file and inherits from the models.model class
• Note: Primary key columns do not need to be defined, they are added automatically in the build and grow automatically
• Book table structure design:
• Book table structure design:

1. The table name: BookInfo
2. Book name: btitle
3. Book release date: bpub_date

• Hero table structure design:

1. The table name: HeroInfo
2. Hero name: hname
3. Hero gender: Hgender
4. Hero profile: hcontent
5. Title: HBook

• The book-hero relationship is one-to-many
• By design, the model class is defined in models.py as follows:

Migration of 2.

• The default is sqlite3 database
• Directory structure before migration

• The migration is done in two steps

1. Generate migration files: Generate statements to create tables from model classes
2. Perform the migration: Create tables in the database based on the statements generated in the first step

• Generate the migration file command

python manage.py makemigrations
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• Run the following migration commands:

• Directory structure after migration:

3. Data operation

• Enter the shell of the project and perform simple API operations
• To exit the shell, press CTRL + D or enter quit ()

python manage.py shell
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• Start by introducing the classes in bookTest/Models

from booktest.models import BookInfo,HeroInfo
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• View all book information

BookInfo.objects.all()
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• The empty list is returned because there is no data currently available

• Creating a New book Object

b=BookInfo()
b.btitle="Legend of the Condor Heroes"
from datetime import date
b.bpub_date=date(1990.1.10)
b.save()
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• Query all books again

b=BookInfo.objects.get(pk=1)
b
b.id
b.btitle
b.bpub_date
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• Modifying book Information

B.b pub_date = date (2017,1,1) b.s ave () b.b pub_dateCopy the code

• Deleting book Information

b.bpub_date=date(2017.1.1)
b.save()
b.bpub_date
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Object associated operations

• You can ctud HeroInfo in the same way as above
• Create a BookInfo object

B = BookInfo () b.b title = 'ABC' b.b pub_date = date (2017,1,1) b.s ave ()Copy the code

• Create a HeroInfo object

h=HeroInfo()
h.htitle='a1'
h.hgender=True
h.hcontent='he is a boy'
h.hBook=b
h.save()
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• Books and heroes have a one-to-many relationship. Django provides related operations
• Get associative collection: Returns all heros of the current book object

b.heroinfo_set.all()
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