DEV Community: aderayevans

Fullstack? Why not (Django + Vue-js) - episode 2

aderayevans — Mon, 04 Jul 2022 15:34:00 +0000

Django side
Vue.js side

Implement episode 2

Django side

{projectname}/urls.py

from django.contrib import admin
from django.urls import include, path

urlpatterns = [
    path('admin/', admin.site.urls),
    path('shark/', include('shark.urls')),
]

shark/urls.py

from django.urls import path
from . import views

app_name = 'shark'
urlpatterns = [
    # path('', views.IndexView.as_view(), name='index'),
    path('', views.index, name='index'),
]

shark/views.py

from urllib import response
from django.shortcuts import render
from django.views import generic
from django.http import HttpResponse
from .models import mShark
from django.http import JsonResponse

def index(request):
    responseData = {
        'id': 4,
        'name': 'Test Response',
        'roles' : ['Admin','User']
    }

    return JsonResponse(responseData)
    # return HttpResponse("return this string")

# Create your views here.
# class IndexView(generic.ListView):
#     # template_name = 'shark/index.html'
#     model = mShark

#     def get_queryset(self):
#         return mShark.getIntro(self)
#         # return HttpResponse("return this string")

shark/models.py

from django.db import models

# Create your models here.
class mShark(models.Model):
    intro = "Hello, This is Shark from Django"

    def getIntro(self) -> set[str]:
        return { mShark.intro }

Vue.js side

frontend/src/router/index.js or .ts

import Vue from "vue";
import VueRouter from "vue-router";
import Shark from "../components/Shark.vue";

Vue.use(VueRouter);

const routes = [
  {
    path: "/shark",
    name: "Shark",
    component: Shark,
  },
];

const router = new VueRouter({
  mode: "history",
  base: process.env.BASE_URL,
  routes,
});

export default router;

Create new file frontend/src/components/Shark.vue

<template>
  <div>
    <p>{{ msg }}</p>
  </div>
</template>

<script>
import axios from "axios";

export default {
  name: "vShark",
  data() {
    return {
      msg: "",
    };
  },
  methods: {
    getResponse() {
      const path = "http://127.0.0.1:8000/shark/";
      axios
        .get(path)
        .then((res) => {
          console.log(res.data);
          this.msg = res.data;
        })
        .catch((err) => {
          console.log(err);
        });
    },
  },
  created() {
    this.getResponse();
  },
};
</script>

Now everytime we go to path http://localhost:8080/shark which is frontend side

Vue will ask the server at http://127.0.0.1:8000/shark/ and get the response
Then print all the messages in the frontend web page

Additional commands:

Run npm run lint --fix to fix linting errors (recommend setting Prettier extension when using VSCode)

Fullstack? Why not (Django + Vue-js) - episode 1

aderayevans — Mon, 04 Jul 2022 15:31:20 +0000

Django side
Vue.js side

Implement episode 1

Django side

Create a new Django project

django-admin startproject {project}

Start the server with

python manage.py runserver

Add application

python manage.py startapp {app}

Migrate database

python manage.py migrate

Change settings before run server

Change the {django-project-dir}\{django-project-name}\settings.py

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

CORS_ORIGIN_ALLOW_ALL = True

MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
    'corsheaders.middleware.CorsMiddleware',
]

shark is an application that I added with startapp

'corsheaders'  
CORS_ORIGIN_ALLOW_ALL = True  
'corsheaders.middleware.CorsMiddleware',

These three line is used for the CORS purpose (Just think that it enabled CORS which allow you pass API between server-client)

Database settings Using sqlite3

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

or Oracle

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.oracle',
        'NAME': 'localhost:1521/XEPDB1',
        'USER': 'django',
        'PASSWORD': 'django',
    }
}

or Mysql

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'polling',
        'HOST': 'localhost',
        'USER': 'djangouser',
        'PASSWORD': 'djangopassword',

        'OPTIONS': {
            'sql_mode': 'traditional',
        }
    }
}

These 3 are patterns I have used in my testing projects.

Run python manage.py migrate to apply these changes

Vue.js side

vue create testfrontend

testfrontend is my frontend project

Start the frontend with

$cd testfrontend
$npm run serve

Fullstack? Why not (Django + Vue-js) - episode 0

aderayevans — Mon, 04 Jul 2022 15:15:20 +0000

Django for backend
Vue.js for frontend

Settings essentials

Django for backend

Anaconda for virtual environment 4.12.0

conda create --name django-env

activate django-env #activate the environment

Remember to install all commands below inside conda env (django_env)

>= Python 3.10.4
Django 4.0.5

python -m pip install Django
Django CORS : Cross-Origin-Resource-Policy

python -m pip install django-cors-headers

Vue.js for frontend

Install Nodejs 16.15.1 and npm 8.11.0 at https://nodejs.org/en/download/
vue-cli 5.0.6

npm install -g vue-cli
axios 0.27.2

npm i axios
typescript 4.7.4 (when cannot find {frontend_project_dir}/node_modules/typescript)

npm install typescript

npm install -g typescript

Additional settings:

add this line to {frontend_project_dir}/jsconfig.json

    "jsx": "preserve",

    {
  "compilerOptions": {
    "target": "es5",
    "jsx": "preserve",
    "module": "esnext",
    "baseUrl": "./",
    "moduleResolution": "node",
    "paths": {
      "@/*": [
        "src/*"
        // "./src/**/*.ts"
      ]
    },
    "lib": [
      "esnext",
      "dom",
      "dom.iterable",
      "scripthost"
    ]
  }
}

Learning ruby - day 3

aderayevans — Mon, 02 Aug 2021 14:53:44 +0000

Table of Contents
Introduction
Take user input
Convert
Pass multiple arguments
Default arguments
Keyword arguments
Block
Proc
Conclusion

Introduction

Hey guys, welcome to my blog recording my ruby self-taught process

I decided to learn this amazing language while I was trying to solving some ruby challenges to get my tenth badge in HackerRank

At the first two days, We have learned about some common collections such as array and hash in ruby. We have also gotten to know with string.

Today, we will learn more about methods and arguments

Take user input

str = gets

p str

Output

"hi\n"

I typed hi and hit Enter

As you can see, it also gets the NEWLINE character, which we don't want to.

So use the chomp method we have learned before to delete that last character at every gets

One more problem here

gets just gets input as raw type, we need to convert it to other type to use it

i = gets.to_i

p i

Output

We converted the input to integer, if you type a non-digit character, i will be 0

Convert

Convert variable types in Ruby is pretty simple.

# String to integer
i = str.to_i
# String to float
f = str.to_f
# Anything to string
str = ob.to_str

# or if you want to catch error unless user type digit
# String to integer
i = Integer(str)
# String to float
f = Float(str)

Pass multiple arguments

def append(*rest)
    str = ""
    rest.each do |x|
        str << x
    end
    str
end

print append("the", " ", "end")

Output

the end

*rest is a array of all arguments passed

Default arguments

def increase(num1, num2 = 1)
    num1 + num2
end
n = 5
puts increase(n)
puts increase(n, 5)

Output

6
10

Keyword arguments

Convert Temperature program using keyword arguments input_scale and output_scale as default arguments

def celsius_kelvin(num)
    return num + 273.15
end

def kelvin_celsius(num)
    return num - 273.15
end

def celsius_fahrenheit(num)
    return num * 1.8 + 32
end

def fahrenheit_celsius(num)
    return (num - 32) / 1.8
end

def kelvin_fahrenheit(num)
    return (num - 273.15) * 1.8
end

def fahrenheit_kelvin(num)
    return ((num - 32) / 1.8) + 273.15
end

def convert_temp(num, input_scale: 'celsius', output_scale: 'celsius')
    return num if input_scale == output_scale
    cmd = input_scale << "_" << output_scale << "(#{num})"
    return eval cmd
end

puts convert_temp(0, input_scale: 'kelvin', output_scale: 'celsius')

puts convert_temp(393, input_scale: 'kelvin', output_scale: 'celsius')

puts convert_temp(400, input_scale: 'fahrenheit', output_scale: 'celsius')

puts convert_temp(333, input_scale: 'fahrenheit', output_scale: 'kelvin')

Output

-273.15
119.85000000000002
204.44444444444443
440.3722222222222

We could also set a hash parameter ** that helps user pass a key argument

def foo(str: "foo", num: 424242, **options)
    options.each_pair do |key, val|
        puts key
        puts options[key]
    end
end

foo(key: "val", key2: "val2")

Output

key
val
key2
val2

Block

Blocks are nameless methods that can be passed to another method as a parameter

def call_block
    puts "Start"
    yield
    puts "End"
end 

# Pass a block {puts "I'm in"} to call_block method
# We can pass with do..end
call_block do 
    puts "I'm in"
end
# or
call_block { puts "I'm in" }

Output

Start
I'm in
End

We can also pass a block to a method that takes parameters

def call_block(a, b)
    puts "Start"
    yield(a, b)
    puts "End"
end 

call_block(12, 23) {|a, b| puts a - b}

Output

Start
-11
End

Proc

"A Proc object is an encapsulation of a block of code, which can be stored in a local variable, passed to a method or another Proc, and can be called."

If Block is a nameless method that can be passed to another method right after the method name

Proc is now the object that holding block, we can pass it as a normal variable to another method

def square_of_sum (arr_, proc_sum, proc_square)
    sum = proc_sum.call(arr_)
    proc_square.call(sum)
end

proc_sum_arr       = proc {|arr| arr.sum}
proc_square_number = proc {|x| x**2}

puts square_of_sum([1, 2], proc_sum_arr, proc_square_number)

If Block codes are called by yield key word

Proc codes are called by call() method

Conclusion

Today we have learned how to take user input, convert variables in ruby

We also have learned some advanced ways to create methods and pass arguments

Knowledged a closure object called Proc, and a nameless method called Block

I'd like to thank HackerRank for giving me a chance to acknowledge and be interesting in this cool language

If guys found Ruby is fascinating, please come to the link below and solve some Ruby challenges with me

https://www.hackerrank.com/domains/ruby

If you have any question or suggestion, please let me know at the comment section below.

OK I'm going to wrap this up here

Thanks for reading my blog

Learning ruby - day 2

aderayevans — Sat, 31 Jul 2021 08:45:06 +0000

Introduction
Content
Conclusion

Introduction

Hey guys, welcome to my blog recording my ruby self-taught process

I decided to learn this amazing language while I was trying to solving some ruby challenges to get my tenth badge in HackerRank

At the first day, We have gotten to know Ruby. If you found it a little hard to understand then let me know immediately, otherwise I will keep writing this blog as a learning process recording

Today I will focus on more details what we have learned at the first day

Print output

Print value of variable and type of variable

name = "Ade"
puts "Hello #{name}!"
puts "#{name.class.name}"

As we have discussed at the first day "Everything is Object", so we're now able to know that type of variable is a class name

Output

PS D:\Workplace> ruby hello-world.rb
Hello Ade!
String

Print raw version of an object, use for debugging string.

P is a kernel method

a = " \n"
p a

Output

" \n"

Pretty printting, use for print Hash object

json = {
    "2019":[
       {
          "language":"Ruby",
          "edition":"seventh"
       },
       {
          "language":"Python",
          "edition":"sixth"
       },
       {
          "language":"Oracle",
          "edition":"second"
       }
    ],
    "2020":[
        {
          "language":"C++",
          "edition":"first"
       },
       {
          "language":"Java",
          "edition":"fourth"
       },
       {
          "language":"Mysql",
          "edition":"third"
       }
    ]
}
puts json
puts "----------------------------------------------------"
pp json

Output

{:"2019"=>[{:language=>"Ruby", :edition=>"seventh"}, {:language=>"Python", :edition=>"sixth"}, {:language=>"Oracle", :edition=>"second"}], :"2020"=>[{:language=>"C++", :edition=>"first"}, {:language=>"Java", :edition=>"fourth"}, {:language=>"Mysql", :edition=>"third"}]}
----------------------------------------------------
{:"2019"=>
  [{:language=>"Ruby", :edition=>"seventh"},
   {:language=>"Python", :edition=>"sixth"},
   {:language=>"Oracle", :edition=>"second"}],
 :"2020"=>
  [{:language=>"C++", :edition=>"first"},
   {:language=>"Java", :edition=>"fourth"},
   {:language=>"Mysql", :edition=>"third"}]}

As you can see, it looks pretty as it name

Too much if - use Case instead

if today == "Monday"
    puts "2, 30 July 2021"
elsif today == "Tuesday"
    puts "3, 30 July 2021"
#...
else
    puts "8, 30 July 2021"
end

case today
when "Monday"
    puts "2, 30 July 2021"
when "Tuesday"
    puts "3, 30 July 2021"
#...
else
    puts "8, 30 July 2021"
end

Output

6, 30 July 2021

Playing with array elements

arr = [65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78]
puts "Array: #{arr.inspect}"
puts "Array length = #{arr.length}"
puts "First element: #{arr[0]}"
puts "First element: #{arr.first}"
puts "Last element: #{arr[-1]}"
puts "Last element: #{arr.last}"
puts "Five first elements #{arr.take(5).inspect}"
puts "Ignores five first elements #{arr.drop(5).inspect}"
puts "Element at index 3 #{arr[3]}"
puts "Elements from index 3 to index 7 #{arr[3..7]}"
puts "Elements from index 3 to index 6 #{arr[3...7]}"
puts "8 Elements from index 3 #{arr[3, 8]}"

Output

Array: [65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78]
Array length = 14
First element: 65
First element: 65
Last element: 78
Last element: 78
Five first elements [65, 66, 67, 68, 69]
Ignores five first elements [70, 71, 72, 73, 74, 75, 76, 77, 78]
Element at index 3 68
Elements from index 3 to index 7 [68, 69, 70, 71, 72]
Elements from index 3 to index 6 [68, 69, 70, 71]
8 Elements from index 3 [68, 69, 70, 71, 72, 73, 74, 75]

inspect help puts print all array elements in one line

Add elements to array

At the last blog, we have learned a bunch of ways to delete elements from array, let's look back a little

arr = [65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78]
puts "Array: \t\t\t#{arr.inspect}"
arr.shift
puts "Delete first element: \t#{arr.inspect}"
arr.pop.inspect
puts "Delete last element: \t#{arr.inspect}"
arr.delete_at(2).inspect
puts "Delete at index 2: \t#{arr.inspect}"

Output

Array:                  [65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78]
Delete first element:   [66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78]
Delete last element:    [66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77]
Delete at index 2:      [66, 67, 69, 70, 71, 72, 73, 74, 75, 76, 77]

Now we're learning some ways to add elements to array

arr = [65, 66, 67, 68, 69, 70]
puts "Array: \t\t\t#{arr.inspect}"
arr.unshift(97, 98)
puts "Add at first position: \t#{arr.inspect}"
arr.push(254, 255)
puts "Add at last position: \t#{arr.inspect}"
arr.insert(5, 128, 129)
puts "Add at index 5: \t#{arr.inspect}"

Output

Array:                  [65, 66, 67, 68, 69, 70]
Add at first position:  [97, 98, 65, 66, 67, 68, 69, 70]
Add at last position:   [97, 98, 65, 66, 67, 68, 69, 70, 254, 255]
Add at index 5:         [97, 98, 65, 66, 67, 128, 129, 68, 69, 70, 254, 255]

As you can see we can add more than just one element

Here document

puts 'Starting', '------------', <<HERE, 'Real Ending'
    1. Salad mix.
    2. Strawberries.
    3. Cereal.
    4. Milk.
HERE

Output

Starting
------------
    1. Salad mix.
    2. Strawberries.
    3. Cereal.
    4. Milk.
Real Ending

This will print 'Starting' and '------------' normally as puts always do

The <<HERE here means the next occurrence of HERE will be the end of this document

'Real Ending' is lying right after the <<HERE, will be print out right after the end of the document

You can set multiple << to exchange words in the document

<<HERE will be failed if there is any space or tab before the next occurrence HERE, <<-HERE is saying the next occurence can have some space, tab or HERE

Please check this link to learn more about this feature

https://en.wikibooks.org/wiki/Ruby_Programming/Here_documents

String

In this part, we're going to talk a little more about string in Ruby

String elements can be called in multiple ways

Each char

str.each_char {|x| p x}

Output

"W"
"h"
"a"
"t"
"'"
"s"
" "
"u"
"p"
"?"

Each byte

str.each_byte {|x| p x}

Output

Each line

"hello\nworld".each_line {|s| p s}

Output

"hello\n"
"world"

We can access elements of a string just like how we do with array

But we cannot delete or add elements to string like we do with array or hash

This is how we do it

Remember these methods will just return a new string, it does not change the original string

Delete last char

str = "Hi   \t\r\n"
p str.chop.chop

Output

"Hi   "

You can see that we can chop multiple time, \r, \n, \r\n (exept \n\r though) will be treat as one char

Delete multiple last chars

str = "Hi, My name is Ade\r\n\r"
p str = str.chomp
p str = str.chomp
p str.chomp "Ade"

Output

"Hi, My name is Ade\r\n"
"Hi, My name is Ade"
"Hi, My name is "

Delete \r or \n or \r\n unless there is a parameter

Delete whitespaces

str = "   \r\n\tHi     ,  Are you having fun?\t   \r    \n"
p str.strip

Output

"Hi     ,  Are you having fun?"

Delete the leading and trailing \t\n\r and whitespaces

Append str

str = ""
str += "Hello"
# or
str = ""
str << "Ruby is " << "pretty"
# How to append non-string
str << 3.14.to_s

Add to the beginning

str = "Gimme your wallet"
p str
p str.prepend("Please, ")

Output

"Gimme your wallet"
"Please, Gimme your wallet"

Check text occurs in str with include

str.include? "wallet"

Replace text in str with gsub, first parameter can be RegExp or String, second parameter is string will replace the occurrence texts

str.gsub(/wallet/, heart)

str = "Please, Gimme your wallet"
if str.include? "wallet"
    puts str.gsub(/wallet/, "heart")
end

Output

Please, Gimme your heart

Conclusion

We have learned more about printing object

Interesting feature called Here document to print multiple line strings

Acknowledged how to access, add and delete elements in array and string, or as i say "playing around with array and string"

I'd like to thank HackerRank for giving me a chance to acknowledge and be interesting in this cool language

If guys found Ruby is fascinating, please come to the link below and solve some Ruby challenges with me

https://www.hackerrank.com/domains/ruby

If you have any question or suggestion, please let me know at the comment section below.

OK I'm going to wrap this up here

Thanks for reading my blog

Learning ruby - day 1

aderayevans — Fri, 30 Jul 2021 10:35:23 +0000

Introduction
Content
Conclusion

Introduction

Hey guys, welcome to my blog recording my ruby self-taught process

I decided to learn this amazing language while I was trying to solving some ruby challenges to get my tenth badge in HackerRank

Ok let's do it

Create my first program in ruby

print "Hello World!!!"

Output

PS D:\Workplace> ruby hello-world.rb
Hello World!!!

print "\n" equals puts

print "First line "
print "still first line\n"
puts "Second line"
puts "Thirld line"

Output

First line still first line
Second line
Thirld line

Everything is object

print else

Output

main

Call Object Method

check whether the num is even or odd

num = 2
print num.even?

Output

true

Call Object Method Parameters

print the quotient of num and 2

num = 2
num.div 2
print num

Output

First loop

print the value of each member in array to the power of 2

array = [1, 2, 3, 4, 5]
array.each do |num|
    puts num.pow 2
end

Output

First function

print ASCII chars of any decimal number in array if number is not odd

def print_char(array)
    array.each do |num|
        puts num.chr unless num.odd?
    end
end
array = [65, 66, 67, 68, 69, 70, 71]
print_char(array)

Output

B
D
F

Array

Working on single element

Delete last element

arr.pop

Delete first element

arr.shift

Delete element at position a given position

arr.delete_at(2)

Working on multiple elements

Delete all occurrences of a given element

arr.delete(5)

Delete elements if

arr.delete_if {|a| a < 2}

Delete elements unless

arr.keep_if {|a| a < 4}

Create subarray

Select elements from array to subarray

arr2 = arr.select {|a| a > 2}
print arr2

Reject elements from array to subarray

arr2 = arr.reject {|a| a > 2}

Reject elements from array till returns false for the first time

arr2 = arr.drop_while {|a| a > 1}

Hash, a dictionary-like data structures

# initialize and set default value
empty_hash = Hash.new 
empty_hash.default = 1
# or
default_hash = Hash.new(1)

Set value

new_hash = {"key1" => 12, "key2" => 50}
# or
new_hash = Hash.new
new_hash["key1"] = 12
new_hash["key2"] = 50
# or
new_hash.store("key1", 12)
new_hash.store(1512032, 50)

Loop with hash

hash.each do |key, value|
    puts key
    puts value
end
# or
hash.each do |array|
    # now key is array[0], value is array[1]
    puts array[0]
    puts array[1]
end

Delete pair

# Delete specific key
hash.delete("key1")
# Delete if
hash.keep_if {|key, value| key.is_a? Integer} 
# or 
hash.delete_if {|key, value|key.even? }

Infinite Loop

i = 0
loop do
    puts i
    i += 1
    break if i == 10
end

Output

Conclusion

We have learned how to print output

How to do some basic loop and function

Learned some common methods of array and a dictionary-like data structures called hash

I'd like to thank HackerRank for giving me a chance to acknowledge and be interesting in this cool language

If guys found Ruby is fascinating, please come to the link below and solve some Ruby challenges with me

https://www.hackerrank.com/domains/ruby

If you have any question or suggestion, please let me know at the comment section below.

OK I'm going to wrap this up here

Thanks for reading my blog

Fixing ORA-65096 error when creating automated tests in Django using Oracle

aderayevans — Wed, 28 Jul 2021 09:33:14 +0000

Introduction
Finding clues
Solution
References

Error: ORA-65096: invalid common user or role name in oracle

Introduction

Hello guys,
I'm new to backend and django, so i had decided to follow along with django tutorial

Here is some detail what i was using to meet and fix this error:

Django version 3.2.5
Database: Oracle Database Express Edition (XE) Release 18.4.0.0.0 (18c)
Windows 11

Next semester, I have a course using Oracle so I decided to use Oracle instead of using Sqlite as the Django tutorial used
I've been struggling with this line 'ORA-65096: invalid common user or role name in oracle' for two days
So I want to create this post as a guide for anyone who meet this problem as i am.

Finding clues

python manage.py test polls

What we should get

Creating test database for alias 'default'...
System check identified no issues (0 silenced).
F
======================================================================
FAIL: test_was_published_recently_with_future_question (polls.tests.QuestionModelTests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/path/to/mysite/polls/tests.py", line 16, in test_was_published_recently_with_future_question
    self.assertIs(future_question.was_published_recently(), False)
AssertionError: True is not False

----------------------------------------------------------------------
Ran 1 test in 0.001s

FAILED (failures=1)
Destroying test database for alias 'default'...

What we actually get :(

Creating test database for alias 'default'...
    Failed (ORA-01543: tablespace 'TEST_SYSTEM' already exists)
    It appears the test database, test_system, already exists. Type 'yes' to delete it, or 'no' to cancel: yes
    Destroying old test database for alias 'default'...
    Creating test user...
    Failed (ORA-65096: invalid common user or role name)
    Got an error creating the test user: ORA-65096: invalid common user or role name

So the program failed when trying to create a new user

Let's open sqlplus to create a new user manually, I get the same error when try to create new user
"ORA-65096: invalid common user or role name"

Why?
I am logging in as an administrator user with full privileges

And so, I do some researches and find out that

SQL> show con_name

CON_NAME
-----------------------------------
CDB$ROOT

We are in the container 'CDB$ROOT', which is the keeper of all the PDBs that are part of the collection
PDB is a Pluggable database
All PDBs are plugged in CDB$ROOT, this structure is called a container database (CDB)
learn more

Aside with those kind of headache, all we need to know is

99.9% of the time the error ORA-65096: invalid common user or role name means you are logged into the CDB when you should be logged into a PDB.

So we need an user have con_name is PDB to create user on that PDB

SQL> show pdbs;

    CON_ID CON_NAME                       OPEN MODE  RESTRICTED
--------------- ------------------------------ ---------- ----------
         2 PDB$SEED                       READ ONLY  NO
         3 XEPDB1                         READ WRITE NO

Here you can see there is a Pluggable database named XEPDB1, because I am using Oracle XE
If you are using Oracle 12 it will be ORCLPDB

Go to solution to see how to create user with PDB

Here we go again, new error showed up

django.db.utils.DatabaseError: ORA-12505: TNS:listener does not currently know of SID given in connect descriptor

Check settings.py file

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.oracle',
        'NAME': 'mydatabase',
        'USER': 'mydatabaseuser',
        'PASSWORD': 'mypassword',
        'HOST': '127.0.0.1',
        'PORT': '1521',
    }
}

Try to login to sqlplus with the user we have just created

PS D:\Workplace\Backend\mysite> sqlplus django/django

SQL*Plus: Release 18.0.0.0.0 - Production on Wed Jul 28 15:56:57 2021
Version 18.4.0.0.0

Copyright (c) 1982, 2018, Oracle.  All rights reserved.

ERROR:
ORA-01017: invalid username/password; logon denied

Hmm, why???

I have tried to create an user with that same username, it says

ORA-01920: user name 'DJANGO' conflicts with another user or role name

Why ????????

Do some research
Found out we cannot use users at Pluggable Database connect to root container

And how do we connect to a specific PDB though?

You are connecting to root container by using sqlplus testtest/password where the user doesn't exist.
Instead, you can use EZConnect or you can create a TNS name to connect to the PDB.

Ok then learn something about ezconnect syntax
sqlplus username/password@hostname:port/pdbname

PS D:\Workplace\Backend\mysite> sqlplus django/django@localhost:1521/XEPDB1

SQL*Plus: Release 18.0.0.0.0 - Production on Wed Jul 28 16:05:09 2021
Version 18.4.0.0.0

Copyright (c) 1982, 2018, Oracle.  All rights reserved.

Last Successful login time: Wed Jul 28 2021 14:18:57 +07:00

Connected to:
Oracle Database 18c Express Edition Release 18.0.0.0.0 - Production
Version 18.4.0.0.0

SQL>

Try to create user

SQL> create user test identified by test;

User created.

Perfect

But how do we tell django using this kind of syntax though, it keep throwing errors to my face

The HOST and PORT keys need to be left out of the dictionary - else Django will try connecting with the complete "NAME" as an SID.

Ok then
Let try to login with service name instead
Try to login with service name in sqlplus

PS D:\Workplace\Backend\mysite> sqlplus -L "django/django@(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=localhost)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=XEPDB1)))"

SQL*Plus: Release 18.0.0.0.0 - Production on Wed Jul 28 12:06:33 2021
Version 18.4.0.0.0

Copyright (c) 1982, 2018, Oracle.  All rights reserved.

Last Successful login time: Wed Jul 28 2021 12:02:04 +07:00

Connected to:
Oracle Database 18c Express Edition Release 18.0.0.0.0 - Production
Version 18.4.0.0.0

Change settings.py a little bit

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.oracle',
        'NAME': 'localhost:1521/XEPDB1',
        'USER': 'django',
        'PASSWORD': 'django',
    }
}

Solution

Connect to sqlplus as sys

PS D:\Workplace\Backend\mysite> sqlplus "sys AS SYSDBA"

SQL*Plus: Release 18.0.0.0.0 - Production on Wed Jul 28 12:47:31 2021
Version 18.4.0.0.0

Copyright (c) 1982, 2018, Oracle.  All rights reserved.

Enter password:

Connected to:
Oracle Database 18c Express Edition Release 18.0.0.0.0 - Production
Version 18.4.0.0.0

Create PDB account

SQL> alter session set container = XEPDB1;

Session altered.

SQL> create user django identified by django;

User created.

SQL> grant all privileges to django;

Grant succeeded.

Create/Edit Database connection with that user Remember to change service name to the container we have used above If you're using Oracle 12, container will be ORCLPDB, hit the connect button
Open file yoursite/yoursite/settings.py

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.oracle',
        'NAME': 'localhost:1521/XEPDB1',
        'USER': 'django',
        'PASSWORD': 'django',
    }
}

If you meet this error, follow my guide here
django.db.utils.DatabaseError: ORA-12505: TNS:listener does not currently know of SID given in connect descriptor

Apply the migrations for app (again because we have connected to a new database)

python manage.py migrate

Run test

PS D:\Workplace\Backend\mysite> python manage.py test polls
Creating test database for alias 'default'...
Creating test user...
System check identified no issues (0 silenced).
F
======================================================================
FAIL: test_was_published_recently_with_future_question (polls.tests.QuestionModelTests)
---------------------------------------------------------------------------
Traceback (most recent call last):
  File "D:\Workplace\Backend\mysite\polls\tests.py", line 12, in test_was_published_recently_with_future_question
    self.assertIs(future_question.was_published_recently(), False)
AssertionError: True is not False

---------------------------------------------------------------------------
Ran 1 test in 0.006s

FAILED (failures=1)
Destroying test database for alias 'default'...
Destroying test user...
Destroying test database tables...

Succeed, thanks for reading

References

Tutorial link
Blogs and stackoverflow-s that helped me through this error:

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Fixing ORA-65096 error when creating automated tests in Django using Oracle

Table of Contents

Introduction

Finding clues

Solution

References