Introduction to Django

This is the 17th day of my participation in Gwen Challenge

The target

Knowledge of virtual environments, Django projects, manage.py directives, and configuration files.

Working with the Django framework gives you a thorough understanding of the development process and basic conceptual elements.

Create your first Django project, the Library Management System (BMSTest).

Preparing the development environment

A programming language	version
Python	3.7.9

This blog installation tutorial is quite detailed: Python environment installation tutorial

Third-party libraries/frameworks	version	instructions
Django	3.1.2	Web Development Framework
virtualenv	20.0.35	Virtual environment library
virtualenvwrapper-win	1.2.6	Virtual Environment Extension Pack (Command convenience)

After installing Python, use the Pip tool to install the Django framework and VirtualEnv

pip install Django

pip install virtualenv
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If you want to specify the version

pip install Django==3.12.

pip install virtualenv==20.035.

pip install virtualenvwrapper-win==1.26.
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The default source may be a bit slow to install the third library, you can configure other mirror sources. Pip installation of third-party libraries slow (Solution)

If you just want to temporarily install the third library faster, you can temporarily use another image source.

pip install -i https://pypi.tuna.tsinghua.edu.cn/simple Django==3.12.
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The development tools	version
Pycharm	2020.2.3
Windows CMD	/

You can install PyCharm pro to develop your Django project

A virtual environment

Understanding virtual Environments

What if you want to develop multiple projects on the same machine and need to use different versions of the same package? If you use the command above, install or update in the same directory, the other projects must not run.

Solution: Virtual environments.

So what is a virtual environment?

Here is a simple example. There is a Word file on the desktop. When we open it and modify it for a while, we find that the original file is better. So what to do? One solution is to make a copy of the file before modifying it, and then make changes in the copy so that if you find errors in the changes, the original file will not be affected.

The virtual environment is essentially a copy of the real Pyhton environment, so that we can install packages in the copied Python environment without affecting the real Python environment. By creating multiple virtual environments, you can isolate projects in different virtual environments.

Virtual environment instruction

instruction	For example,	role
mkvirtualenv	Mkvirtualenv -p python3 Name of the virtual environment	Creating a Virtual Environment
deactivate	deactivate	Exiting a Virtual Environment
workon	workon	Viewing a Virtual Environment
workon	Workon Indicates the name of a virtual environment	Using virtual Environments
rmvirtualenv	Rmvirtualenv Virtual environment name	Deleting a Virtual Environment

Note:

Deactivate: deactivate: rmVirtualenv Specifies the name of the virtual environmentCopy the code

Virtual Environment Creation

Create the PYTHon3 virtual environment py_django in a CMD window:

mkvirtualenv -p python3 py_django
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It is recommended that you create a DjangoProject folder just to learn and practice your Django project.

Note:

The default virtual environment to be created is C:\Users\Administrator\Envs. Administrator represents the user that I am currently using on my computer. You may specify a path for storing the virtual environment under other Users. You can add the WORKON_HOME system variable to your computer’s system environment variables

Library Management System (BMSTest) project

Install the Django framework in a virtual environment

First, enter the Py_Django virtual environment

workon py_django
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PIP then installs Django

pip install django
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Finally, check whether the installation is successful

pip list
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Create the BMSTest project

Django-admin startProject Project name Example: Django-admin startproject BMSTestCopy the code

Use the CMD dir command to see if the project was created successfully

PyCharm opens the project

Django project directory structure

Django project directory description

The file name	role
manage.py	Project management file through which to manage the project
BMSTest	Directory with the same name as the project, in this case BMSTest
__init__.py	An empty file that allows the directory BMSTest to be used as a package
asgi.py	Django3.0 is a new asynchronous function module
settings.py	The overall configuration file for the project
urls.py	The URL configuration file for the project
wsgi.py	Wsgi-compliant Web server entry for the project

Creating the project application

Enter the Virtual Environment

Find the Terminal option in the lower left corner of Pycharm and turn it on

Then use the workon command to enter the virtual environment

PyCharm’s Terminal is the same as the CMD window.

Creating the Book app

Enter the command in the Terminal to create the Book application

python manage.py startapp book
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Then refresh or wait and PyCharm will show you the app you created

Djangos application directory description

Folders/files	role
__init__.py	Is an empty file indicating that the current directory book can be used as a Python package
migrations	Database Migration folder
admin.py	Related to the backstage management of the website
apps.py	Django generates the name of the app file
models.py	Database operation related
tests.py	For developing test cases, there will be dedicated testers in the actual development
views.py	Receives the browser request, processes it, and returns the page relevant

Install the application

Find INSTALLED_APPS in setting.py under BMSTest and add the Django application you just created (book) after it.

Run the Django project on the Web server

During development, Django provides a lightweight Web server written in pure Python to be used only during development, in order to quickly preview the effects of development.

Enter the following command in the PyCharm Terminal to run the server:

Python manage.py runserver IP: port For example, run python manage.py runserverCopy the code

You can omit the IP address and port. The default IP address is 127.0.0.1 and the default port is 8000.

Click the blue url or copy the url to open it in your browser to display the Django project’s default home page.

To end the server, press Ctrl + C on the PyCharm Terminal

The Chinese language and Chinese time zone are configured

Find LANGUAGE_CODE and TIME_ZONE in the BMSTest project setting. Py and set it to:

LANGUAGE_CODE = 'zh-hans'   Configure the Chinese language

TIME_ZONE = 'Asia/Shanghai' # Set China time zone
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Once you’re done setting up and running the server, your Django project’s home page becomes Chinese.

The public,

Create a new folder X

Nature took tens of billions of years to create our real world, while programmers took hundreds of years to create a completely different virtual world. We knock out brick by brick with a keyboard and build everything with our brains. People see 1000 as authority. We defend 1024. We are not keyboard warriors, we are just extraordinary builders of ordinary world.