当前位置：网站首页>[encounter Django] - (II) database configuration

This series of articles , stay Django Under the basic template of the official document tutorial , Some improvements and deletions have been made , Added some of my own insights .

I hope that after reading this series of articles , Yes Django Be able to have a clear understanding .

It's a long way to go , I will go up and down ！

Django Official documents ： https://www.djangoproject.com/

Learning process , Read more official documents , Can solve many problems

This tutorial USES poetry Manage the project environment .
relevant poetry Installation and use of , Please refer to 【Python - A virtual environment 】 The start of the project , Start by isolating the development environment _CoderChaos Technology blog _51CTO Blog

One 、 Project profile `settings.py`

1.1 Database configuration

mysite/settings.py , It's a that includes Django Project settings Python modular .

Configuration of database , It's the variables DATABASES.

Django By default SQLite As the default database .Python built-in SQLite, So you don't need to install extra things to use .

If you do a real project , Better not to use SQLite.

# Django  By default  SQLite
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': BASE_DIR / 'db.sqlite3',
    }
}

# Django Use MySQL To configure 
DATABASES = {
	'default': {
		'ENGINE': 'django.db.backends.mysql',
		'NAME': 'mysite', #  Use MySQL when , Need to be ahead of time MySQL establish mysite database 
		'HOST': '127.0.0.1',
		'PORT': 3306,
		'USER': 'root',
		'PASSWORD': '******'
	}
}

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Parameter description ：

default：Django When connecting to the database , Default link default Database under .
ENGINE： There are multiple options
- django.db.backends.sqlite3
- django.db.backends.postgresql
- django.db.backends.mysql
- django.db.backends.oracle
- Other third-party database backend . Reference address
NAME： Database name . If you use SQLite, The database will be a file on the computer . The default value is BASE_DIR / 'db.sqlite3', The database will be stored in the root directory of the project .
The other parameters ： If not used SQLite, You must add some additional settings , such as USER、PASSWORD、HOST wait . Reference documents

Be careful ： If you use SQLite Other databases , You need to make sure that you have created the database before using it . You can use it in your database interactive command line CREATE DATABASE database_name; To complete the creation of the database .

1.2 Time zone and language

Can be in settings.py In file , Modify time zone and language .

1.3 `Django` The default self-contained application profile

settings.py Some notes in the document ：INSTALLED_APPS
INSTALLED_APPS The default includes the following Django Built in application of ：

django.contrib.admin： Administrator site
django.contrib.auth： Authentication and authorization system
django.contrib.contenttypes： Content type framework
django.contrib.sessions： Conversational framework
django.contrib.messages： Message frame
django.contrib.staticfiles： Framework for managing static files

Some applications opened by default need at least one data table , therefore , Before using them, you need to create some tables in the database . The following commands need to be executed ：python manage.py migrate

Two 、 Creating models

Defining models , That is, database structure design and additional metadata .

In this voting application , You need to create two models ： problem Question And options Choice.

Question The model includes problem description and release time .
Choice The model includes the option description and the current number of votes . Each option belongs to a question .

# polls/models.py
from django.db import models


class Question(models.Model):
    question_text = models.CharField(max_length=200)
    pub_date = models.DateTimeField(" Release date ")


class Choice(models.Model):
    question = models.ForeignKey(Question, on_delete=models.CASCADE)
    choice_text = models.CharField(max_length=200)
    votes = models.IntegerField(default=0)

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Creating models , Inherit django.db.models.Model; Each model has many class variables , Both represent a data table field in the model .

Each field is Field Class .

explain ：

Django You can create database tables for applications （CREATE TABLE）
Django Can be created with Question and Choice Objects interact Python database API

3、 ... and 、 Activate the model

Django The application is “ Pluggable ” Of .

add to polls application

# mysite/settings.py
INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    
    'polls',
    #  or 'polls.apps.PollsConfig',
]

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Now? ,Django The project already contains polls application .

Run the command makemigrations, Perform a migration ：python manage.py makemigrations

function makemigrations command ,Django It will detect the modification of the model file , And store the modified part as a migration . Migration is Django A storage of data structure changes .

migrate Is a command that automatically performs database migration and synchronously manages the database structure .

therefore , perform makemigrations after , To modify the synchronization in the database , Need to execute again python manage.py migrate.

Migration is a very powerful feature , It can continuously change the database structure during the development process without deleting tables and recreating tables .
It focuses on smooth database upgrade without data loss .

Changing the model requires the following steps ：

edit models.py file , Change the model
function python manage.py makemigrateions Generate migration files for model changes
function python manage.py migrate Application database migration

Four 、 First try API

4.1 `Django` Basic use of interactive commands

Get into Django Interactive command line ：python manage.py shell

>>> from polls.models import Choice, Question
#  See the table Question Table data 
>>> Question.objects.all()
<QuerySet []> #  There's no data right now 

>>> from django.utils import timezone
#  Create a Question Data objects 
>>> q = Question(question_text="What's new?", pub_date=timezone.now())
#  Store data objects to the database 
>>> q.save()
#  see  q  Object properties 
>>> q.id
1
>>> q.question_text
"What's' new?"
>>> q.pub_date
datetime.datetime(2022, 3, 20, 11, 29, 15, 780052, tzinfo=datetime.timezone.utc)

#  modify  q  Object properties 
>>> q.question_text = "What's up?"
>>> q.save()

#  Look again  Question  Table data 
>>> Question.objects.all()
<QuerySet [<Question: Question object (1)>]>

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about Question Returned display data , You can edit Question Modify the model code , to Question and Chioce increase __str__() Method .

class Question(models.Model):
    question_text = models.CharField(max_length=200)
    pub_date = models.DateTimeField(" Release date ")
    
    def __str__(self):
        return self.question_text


class Choice(models.Model):
    question = models.ForeignKey(Question, on_delete=models.CASCADE)
    choice_text = models.CharField(max_length=200)
    votes = models.IntegerField(default=0)
    
    def __str__(self):
        return self.choice_text

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Once again into the Django Interactive command line ：python manage.py shell

4.2 Add custom methods to the model

import datetime

from django.db import models
from django.utils import timezone


class Question(models.Model):
    question_text = models.CharField(max_length=200)
    pub_date = models.DateTimeField(" Release date ")

    def __str__(self):
        return self.question_text

    def was_published_recently(self):
        return self.pub_date >= timezone.now() - datetime.timedelta(days=1)

class Choice(models.Model):
    question = models.ForeignKey(Question, on_delete=models.CASCADE)
    choice_text = models.CharField(max_length=200)
    votes = models.IntegerField(default=0)

    def __str__(self):
        return self.choice_text

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Once again into the Django Interactive command line ：python manage.py shell

>>> from polls.models import Question, Choice

#  see  __str__()  Whether it is in effect 
>>> Question.objects.all()
<QuerySet [<Question: What's up?>]>

# Django database API：filter
>>> Question.objects.filter(id=1)
<QuerySet [<Question: What's up?>]>
>>> from django.utils import timezone
>>> current_year = timezone.now().year
>>> Question.objects.get(pub_date__year=current_year)
<Question: What's up?>

#  If there is no data in the database , An exception will be thrown 
>>> Question.objects.get(id=2)
Traceback (most recent call last):
  File "<input>", line 1, in <module>
  File "D:\Codes\media\django\code001\venv\lib\site-packages\django\db\models\manager.py", line 85, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "D:\Codes\media\django\code001\venv\lib\site-packages\django\db\models\query.py", line 496, in get
    raise self.model.DoesNotExist(
polls.models.Question.DoesNotExist: Question matching query does not exist.

#  Get data object through primary key 
>>> Question.objects.get(pk=1)
<Question: What's up?>
>>> q = Question.objects.get(pk=1)

#  Use  models.py  Custom methods in 
>>> q.was_published_recently()
True

#  see  q  object , The object corresponding to the foreign key 
>>> q.choice_set.all()
<QuerySet []>

#  to  q  Object to add foreign key elements 
>>> q.choice_set.create(choice_text="Not much", votes=0)
<Choice: Not much>
>>> q.choice_set.create(choice_text="The sky", votes=0)
<Choice: The sky>
>>> c = q.choice_set.create(choice_text="Just hacking again", votes=0)

#  see  c  Elements （Choice  object ）
>>> c
<Choice: Just hacking again>
#  see  c  Attribute of element 
>>> c.question
<Question: What's up?>

#  see  q  object , The object corresponding to the foreign key 
>>> q.choice_set.all()
<QuerySet [<Choice: Not much>, <Choice: The sky>, <Choice: Just hacking again>]>
>>> q.choice_set.count()
3

>>> Choice.objects.filter(question__pub_date__year=current_year)
<QuerySet [<Choice: Not much>, <Choice: The sky>, <Choice: Just hacking again>]>

>>> c = q.choice_set.filter(choice_text__startswith="Just hacking")
#  Delete  c  object 
>>> c.delete()
(1, {'polls.Choice': 1})
>>> q.choice_set.all()
<QuerySet [<Choice: Not much>, <Choice: The sky>]>

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5、 ... and 、`Djaong` Management interface

The management interface is not for visitors to the website , But for managers .

5.1 Create an administrator account

Run the following command on the command line ：python manage.py createsuperuser
You will be prompted later , enter one user name 、 mailbox 、 password 、 Confirm the password .

> python manage.py createsuperuser
 user name  (leave blank to use 'administrator'): admin
 E-mail address : [email protected].com
Password: ******
Password (again): ******
 The password length is too short . The password must contain at least  8  Characters .
 This password is so common .
 The password contains only numbers .
Bypass password validation and create user anyway? [y/N]: y
Superuser created successfully.

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5.2 Login management interface

Start development server ：python manage.py runserver
Open the browser ： http://127.0.0.1:8000/admin/
Enter your account and password , You can enter the management interface .

【 to encounter Django】——（ Two ） Database configuration _django

【 to encounter Django】——（ Two ） Database configuration _ database _02

5.3 Add voting application to the management page

【 to encounter Django】——（ Two ） Database configuration _django_03

5.4 Experience convenient management functions

Click the button in the page , You can use the add / delete / modify query function .

6、 ... and 、【`PyCharm` Use tips 】

6.1 Use `PyCharm` Tools for running `makemigrations & migrate`

【 to encounter Django】——（ Two ） Database configuration _ database _04

6.2 Use `PyCharm` function `django shell`

stay PyCharm Bottom toolbar , choice Python Console You can enter python manage.py shell.

Prerequisite ： Project start Django Support .
Project start Django Support see ：【 to encounter Django】——（ One ） Create project _CoderChaos Technology blog _51CTO Blog
Four 、【PyCharm Use tips 】

Compared with from Terminal adopt python manage.py shell Get into Django shell, There will be a certain prompt when entering .

【 to encounter Django】——（ Two ） Database configuration _django_05

7、 ... and 、 The simplest beautification Django Admin

7.1 `simpleui` brief introduction

Django Admin The default interface design language has some shortcomings , For example, the color is single , The use of a large number of lines , Segmentation is obvious . Categorizing these deficiencies is the monotonous interface 、 The similarity is obvious 、 Lack of surprises .

simpleui： Based on a vue+element-ui Of django admin The theme of modernization .

GitHub Address ： https://github.com/newpanjing/simpleui

7.2 `simpleui` Use

7.2.1 install

7.2.2 Start using

After installation , In my own project settings.py In file INSTALLED_APPS Of first line Join in simpleui.

# settings.py
INSTALLED_APPS = [
    'simpleui',
    
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',

    'polls'
]

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If the previous service is still running , Refresh the page .

【 to encounter Django】——（ Two ） Database configuration _ database _06

【 to encounter Django】——（ Two ） Database configuration _ database _07

summary

This article briefly introduces Django Connection and use with database , Use of the default background management interface .

And the use of PyCharm Quick operation makemigrations & migrate Command and django shell, Use django-simpleui Beautify the default background management interface .

原网站

版权声明
本文为[51CTO]所创，转载请带上原文链接，感谢
https://yzsam.com/2022/182/202207011232346452.html

当前位置：网站首页>[encounter Django] - (II) database configuration

[encounter Django] - (II) database configuration

to encounter Django - Catalog

List of articles

Preface

One 、 Project profile `settings.py`

1.1 Database configuration

1.2 Time zone and language

1.3 `Django` The default self-contained application profile

Two 、 Creating models

3、 ... and 、 Activate the model

Four 、 First try API

4.1 `Django` Basic use of interactive commands

4.2 Add custom methods to the model

5、 ... and 、`Djaong` Management interface

5.1 Create an administrator account

5.2 Login management interface

5.3 Add voting application to the management page

5.4 Experience convenient management functions

6、 ... and 、【`PyCharm` Use tips 】

6.1 Use `PyCharm` Tools for running `makemigrations & migrate`

6.2 Use `PyCharm` function `django shell`

7、 ... and 、 The simplest beautification Django Admin

7.1 `simpleui` brief introduction

7.2 `simpleui` Use

7.2.1 install

7.2.2 Start using

summary

边栏推荐

猜你喜欢

随机推荐

当前位置：网站首页>[encounter Django] - (II) database configuration

[encounter Django] - (II) database configuration

to encounter Django - Catalog

List of articles

Preface

One 、 Project profile settings.py

1.1 Database configuration

1.2 Time zone and language

1.3 Django The default self-contained application profile

Two 、 Creating models

3、 ... and 、 Activate the model

Four 、 First try API

4.1 Django Basic use of interactive commands

4.2 Add custom methods to the model

5、 ... and 、Djaong Management interface

5.1 Create an administrator account

5.2 Login management interface

5.3 Add voting application to the management page

5.4 Experience convenient management functions

6、 ... and 、【PyCharm Use tips 】

6.1 Use PyCharm Tools for running makemigrations & migrate

6.2 Use PyCharm function django shell

7、 ... and 、 The simplest beautification Django Admin

7.1 simpleui brief introduction

7.2 simpleui Use

7.2.1 install

7.2.2 Start using

summary

边栏推荐

猜你喜欢

随机推荐

One 、 Project profile `settings.py`

1.3 `Django` The default self-contained application profile

4.1 `Django` Basic use of interactive commands

5、 ... and 、`Djaong` Management interface

6、 ... and 、【`PyCharm` Use tips 】

6.1 Use `PyCharm` Tools for running `makemigrations & migrate`

6.2 Use `PyCharm` function `django shell`

7.1 `simpleui` brief introduction

7.2 `simpleui` Use