Getting started with Django

Getting started with Django

 

Take the "books-heroes" management as an example to use Django to develop the basic process and learn the main knowledge of Django.

Install Django

pip install django

Note: When you use the pip install django command for installation, the old version is automatically deleted and the new version is installed.

Create a project

Command: django-admin startproject test1

Note: In the above command, "test1" is the name of the project you want to create.

Go to the test1 directory. The directory structure is as follows:

Note:

• Manage. py: a command line tool that allows you to interact with Django projects in multiple ways
• Test1: Real Python package of the project
• _ Init _. py: An empty file, which is required by the Python package.
• Settings. py: project configuration file
• Urls. py: project URL Declaration
• Wsgi. py: entry to the Web server compatible with WSGI

Design Introduction

This project maintains the information of "books-heroes" and stores two types of data: Books and heroes.

Structure Design of books and tables:

Table Name: BookInfo

Book name: btitle

Book Release Date: bpub_date

Hero table structure design:

Table Name: HeroInfo

Hero name: hname

Gender: hgender

Hero Introduction: hcontent

Book: hbook

Book-hero relationship: one-to-many

Database Configuration

In the settings. py file, use the DATABASES item to set the database.

# Database# https://docs.djangoproject.com/en/1.11/ref/settings/#databasesDATABASES = {    'default': {        'ENGINE': 'django.db.backends.sqlite3',        'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),    }}

Django supports mainstream databases such as sqlite and mysql.

Django uses the sqlite database by default.

Create an application

One or more applications can be created in a project, and each application performs one business operation.

Command for creating an application: python manage. py startapp booktest

Note: The "booktest" in the above command is the name of the application you want to create

The application directory structure is as follows:

Define model end

A data table corresponds to a model class.

Open the models. py file and define the model class.

Import package from django. db import models

The Model class is inherited from the models. Model class.

Note: you do not need to define a primary key column. It will be automatically added during production and the value will automatically increase.

When an object is output, the str method of the object is called.

# Booktest/models. pyfrom django. db import models "Table Structure Design: Table Name: BookInfo book name: btitle book release date: bpub_date hero table structure design: Table Name: HeroInfo hero name: hname hero gender: hgender hero Introduction: hcontent book: hbook book-the relationship between heroes is one-to-many "" # Create your models here. # Library class BookInfo (models. model): btitle = models. charField (max_length = 20) bpub_date = models. dateTimeField () def _ str _ (self): return self. btitle # HeroInfo (models. model): hname = models. charField (max_length = 20) hgender = models. nullBooleanField () hcontent = models. charField (max_length = 1000) hbook = models. foreignKey ('bookinfo') def _ str _ (self): return self. hname

Generate data table

Activate model: edit the settings. py file and add the booktest application to INSTALLED_APPS.

# Application definitionINSTALLED_APPS = [    'django.contrib.admin',    'django.contrib.auth',    'django.contrib.contenttypes',    'django.contrib.sessions',    'django.contrib.messages',    'django.contrib.staticfiles',    'booktest',]

Generate a migration file: generate an SQL statement: python manage. py makemigrations

The migration file is generated to the migrations directory of the application.

　　

Execute migration: Execute an SQL statement to generate a data table: python manage. py migrate

Test data operations

Go to python shell and perform simple model API exercises: python manage. py shell

After entering the shell, the prompt is as follows:

　　

# Introduce the required package:

From booktest. models import BookInfo, HeroInfo

From datetime import *

# Creating a book

B = BookInfo ()

B. btitle = "Legend of the legend"

B. bpub_date = datetime (year = 1990, month = 1, day = 10)

B. save ()

# Query information of all books:

BookInfo. objects. all ()

# Query the book information based on the conditions (the primary key is the primary key)

B = BookInfo. objects. get (pk = 1)

# Output book information

B

B. id

B. btitle

# Modifying book information

B. btitle = "tianlong Babu"

B. save ()

# Deleting Book Information

B. delete ()

Associated object operations

HeroInfo can be operated as described above

Add. Note: add the associated object.

H = HeroInfo ()

H. htitle = "Guo Jing"

H. hgender = True

H. hcontent = ""

H. hbook = B

H. save ()

 

To be continued ......