To read existing JSON content from local files:

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const fs = require('fs')
try {
    const dataBuffer = fs.readFileSync('<json file name>')
    const dataJSON = dataBuffer.toString()
    return JSON.parse(dataJSON)
} catch (e) {
    return []
}

To save text to JSON files:

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const fs = require('fs')
const dataJSON = JSON.stringify(notes)
fs.writeFileSync('<json file name>', dataJSON)

Django directory levels

1. manage.py: we use this to communicate with Django server
2. project directory:
   1. __init__.py: tells Django to use directory as a python package
   2. settings.py: Django configuration file
   3. urls.py: url schema
   4. wsgi.py: project and wsgi integration web server

Database (MySQL) config

• dependencies used:
  mysql 5.7.24 h56848d4_0
  mysql-connector-c 6.1.11 hccea1a4_0
  mysql-connector-python 8.0.17 py27h3febbb0_0 anaconda
  mysql-python 1.2.5 py27h1de35cc_0 anaconda
  pymysql 0.9.3 py27_0
• __init__.py:, add the following code:

  1 2	import pymysql pymysql.install_as_MySQLdb()

• in settings.py: add database configurations to connect to the database

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  DATABASES = { 'default': { 'ENGINE': 'django.db.backends.mysql', 'NAME': # server name 'USER': # user name 'PASSWORD': # password 'HOST': 'localhost', 'PORT': '3306', } }

Init new application

• init new application:

  1	python manage.py startapp <myApp>

• codes above creates:
  • admin.py: website config
  • models.py: model
  • views.py: view
• In setting, add to INSTALLED_APP:

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  INSTALLED_APPS = [ 'django.contrib.admin', 'django.contrib.auth', 'django.contrib.contenttypes', 'django.contrib.sessions', 'django.contrib.messages', 'django.contrib.staticfiles', 'myApp' ]

models.py file

• the following is an example of models.py

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  # -*- coding: utf-8 -*- from __future__ import unicode_literals from django.db import models # Create your models here. class Grades(models.Model): gname = models.CharField(max_length=20) gdate = models.DateTimeField() ggirlnum = models.IntegerField() gboynum = models.IntegerField() isDelete = models.BooleanField(default=False) def __str__(self): return "%s-%d-%d"%(self.gname, self.gboynum, self.ggrilnum) class Students(models.Model): sname = models.CharField(max_length=20) sgender = models.BooleanField(default=True) sage = models.IntegerField() scontend = models.CharField(max_length=20) isDelete = models.BooleanField(default=False) sgrade = models.ForeignKey("Grades") def __str__(self): return "%s-%d-%s"%(self.sname, self.sage, self.scontend)

• make migration and execute migration file: will create database according to models.py

  1 2	python manage.py makemigrations # create migration file python manage.py migrate # execute migration file

To add new entries with manage.py shell commands

1. enter shell:

   1	python manage.py shell

2. import packages in shell:

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   from myApp.models import Grades, Students from django.utils import timezone from datetime import *

3. add new entry to db:

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   grade1 = Grades() grade1.gname = "something" grade1.gdate = datetime(year=,month=,day=) grade1.ggirlnum = 70 grade1.gboynum = 35 grade1.save()

4. some other command:

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   Grades.objects.all() # get all data entries in Grades g = Grades.objects.get(pk=1) # get the 1st object in Grades g.gboynum = 45 g.save() # alternate existing data d.delete() # delete, including the one in db stu1 = g.students_set.create(sname=...) # add new student with one line

To run server

• execute:

  1	python manage.py runserver ip:port

• Admin:
  • publish content
  • add/modify/delete content
  • add “‘django.contrib.admin’” in INSTALLED_APPS
  • exists by defualt
  • add “/admin” and log in
  • change language or timezone based on preference

(to be continued…)