In addition to putting the installed modules (the source code of the framework, which needs to be imported and used) into ..../Lib/site-pachages, django will also produce a file (this is a tool to help us create projects) Put it in ..../Scripts.

2. Create a project

Projects in django will have some default files and default folders

2.1 Steps to create in the terminal

open terminal
Enter a directory (where the project wants to be placed)

D:\django idea\disease predication>

Execute the command to create the project

在django-admin所在目录执行命令
"D:\software\study software\pycharm\python\Scripts\django-admin.exe" startproject 项目名称

如果D:\software\study software\pycharm\python\Scripts已经加入到系统环境变量，则可执行：
django-admin.exe startproject 项目名称

Implementation process

Execute the command to create the project and an overview of the project file after the creation is successful:

2.2 Use pycharm (Enterprise Edition) to create a django project

Create operation:

2.3 Comparing the two methods

command line: the created project is standard
pycharm: Added something by default on the basis of the standard

1. Create a templates directory, and then [delete]

2. There is one more sentence in settings.py [delete]

2.4 Default file introduction

2.5 app creation and specification

App is an application. Large-scale projects can be written in Django. Each large project has many classified small functions, and it supports splitting into small apps.

——项目
    ——app,用户管理【表结构、函数、HTML模板、CSS】
    ——app,订单管理
    ——app，API
    ——app,网站
每一个app可以有自己独立的数据库的表结构.....

Create app:

Enter the terminal in the directory where the file is located, and execute the python manage.py startapp app01 command to create the app. However, the following error occurred during the creation process: Failed to resolve

Reference: http://t.csdn.cn/imPci

The project has been re-established, and the app can be successfully created at present, and the subsequent operation and learning will start with the newly created djangoProject project

app directory:

2.6 Start and run django

Make sure the app is registered [settings.py]
Write the corresponding relationship between URL and view function [urls.py]
Write view function [views.py]

If the user visits this URL, this function will be executed, and the function returns a "Welcome" string, which will appear on the user's browser.

Start the django project
- Command line start: python manage.py runserver
- PyCharm starts:

Note: The loading directory is incorrect, which may cause project errors

2.7 Templates and static files

2.7.1 Write another page

After all the configurations are done, the essence of development afterwards is: add a corresponding relationship in urls, and write a view function in views to process the request.

2.7.2 templates

returns an HTML

2.7.3 Static files

Create a static folder under the app directory

Import static files

2.8 django's template syntax

The template syntax is developed by django, the essence: write some placeholders in HTML, and replace and process these placeholders by data

Received by the user's browser:

the case

Pseudo Unicom Message Center

http://www.chinaunicom.com/news/list202304.html

Subsequent improvement

2.9 Request and response

3 requests

The GET request is passed on the surface, and the POST request is passed secretly, which cannot be seen on the surface

3 responses

About redirection: the browser sends a request to a certain website, and the return value of a certain website tells the browser that you should go to another place, and the browser goes to this place by itself, which has nothing to do with the website, which is the second form in the figure below:

Case: user login

Error resolution:

The solution to the above error is as follows: By default, Django has one more function than Flask, CSRF token verification

code:

An effect finally achieved:

2.10orm_connecting MySQL module

Django development introduces a mechanism for easier operation of the database. It is easier to operate the database, and an ORM framework is provided internally.

Install third-party modules:

pip install  mysqlclient

Error installing:

Solution:

2.11orm-create database

ORM can help us do two things:

Create, delete, and modify tables in the database (no need to write SQL statements yourself) [Unable to create database]
Operate the data in the table (no need to write SQL statements) because Django will translate the code you write into SQl statements through ORM

1. Create your own database

Start the MySQL service

Self-contained tool to create database

create database gx_day14 DEFAULT CHARSET utf8 COLLATE utf8_general_ci;

Basic database learning: (144 messages) Database and identity authentication_Cannon doesn't want to learn Blog-CSDN Blog

2.12 configuration of orm_connection to MySQL

Mysql environment variable configuration of my computer:

Configure environment variables

See if the configuration is successful

2. Django connects to the database

Configure and modify in the settings.py file

The sqllite file database used by the default Database

Change to the following: Django will help us connect to the database by default

2.13orm_class create table

3. Django operation table

create table
delete table
modify table

Create table: in models.py

# UserInfo是类 必须继承  models.Model
class UserInfo(models.Model):
    # 字段
    name = models.CharField(max_length=32)
    password = models.CharField(max_length=64)
    age = models.IntegerField()

Excuting an order:

python manage.py makemigrations
python manage.py migrate

Notice:

Make sure the python interpreter has Mysqlclient installed
Make sure the current path is the root directory of the current project
The app needs to be registered in advance (the app is not registered in setting.py, and the tables in models.py will not be submitted to the database)

It is particularly error-prone here, change the interpreter and reinstall

Finally, enter the directory where manage.py is located, open the terminal, and execute the command to successfully install it! ! ! !

However, after the above installation operation, the subsequent table cannot be found in the database

Note: There can be no Chinese in the path of the project, and the location of the project that was later moved, re-executed the following command:

pip install mysqlcliennt
python manage.py makemigrations
python manage.py migrate

Why are there other tables besides app01_userinfo? Because once the command is executed, go back and find the models.py in each app to generate the corresponding table according to the statement, but Django provides many other apps by default (the functions provided by django, these functions are all dependent on some tables of the database) , it can be seen in setting.py, so when the table is generated, some default tables are also generated. If you don’t want to use the corresponding position in the picture below, just comment it out

Enter the command desc app01_userinfo; you can see the created table

2.14 orm_ create and modify table structure

Add (below)/delete tables ( delete the corresponding statement, then re-execute the 2 command statements )

Modify a column in a table

Since there may be data in existing columns, the new column must specify the data corresponding to the new column:

Enter value manually
set default
Allow empty

In the future, I want to adjust the table structure during development

Just operate the class in the models.py file, and then execute the command:

python manage.py makemigrations
python manage.py migrate

2.15orm- add, delete, modify and check

Manipulate data in the table

new data

Write a url to test the function

New data:

    # #### 1.新建 ####
    # Department.objects.create(title="销售部")
    # Department.objects.create(title="IT部")
    # Department.objects.create(title="运营部")
    # UserInfo.objects.create(name="武沛齐", password="123", age=19)
    # UserInfo.objects.create(name="朱虎飞", password="666", age=29)
    # UserInfo.objects.create(name="吴阳军", password="666")

delete data:

    # #### 2.删除 ####
    # UserInfo.objects.filter(id=3).delete()
    # Department.objects.all().delete()
    # UserInfo.objects.all().delete()

retrieve data:

Get all data matching the criteria

Get a row of data

update data:

    # #### 4.更新数据 ####
    UserInfo.objects.all().update(password=999)
    UserInfo.objects.filter(id=19).update(age=999)
    UserInfo.objects.filter(name="朱虎飞").update(age=999)
    return HttpResponse("耶耶耶")

Case: User Management

1. Display user list

url.py
view.py function
Get information about all users

html rendering

2. Add users

Implement the user input user, and then add to the database

url.py
view.py function

GET: see the page, enter content

POST: submit --> write to the database

Add button on the list page, click to jump directly to the add page

3. Delete user

url.py
view.py function

需求

http://127.0.0.1:8000/info/delete/?nid=1
http://127.0.0.1:8000/info/delete/?nid=2
http://127.0.0.1:8000/info/delete/?nid=21

def 函数（request）:
    #.GET在url后边获取传过来的参数，POST是获取请求体传过来的值
    nid=request.GET.get("nid")
    UserInfo.objects.filter(id=nid).delete()
    return HttpResponse("删除成功")

Django learning - installation, project creation, database, user management case

1. Install django

1.1django is a third-party module, installed with pip install django :

1.2 Python installation directory: