Django Materials - Rishi Python - May 2020

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PYTHON DJANGO By Rishi JANUARY 1, 2019 RISHI.H2KINFOSYS@GMAIL.COM www.h2kinfosys.com

Rishi – Python Django C:\>cd Rishi C:\RISHI>cd Dev C:\RISHI\Dev>mkdir myDjang C:\RISHI\Dev>dir Volume in drive C is Windows Volume Serial Number is 0CDC-A763 Directory of C:\RISHI\Dev 31-07-2019 21:38 <DIR> . 31-07-2019 21:38 <DIR> .. 31-07-2019 21:38 <DIR> myDjang 0 File(s) 0 bytes 8 Dir(s) 575,761,174,528 bytes free C:\RISHI\Dev>cd myDjang C:\RISHI\Dev\aprDjango>virtualenv . created virtual environment CPython3.8.2.final.0-32 in 19295ms creator CPython3Windows(dest=C:\RISHI\Dev\aprDjango, clear=False, global=False) seeder FromAppData(download=False, pip=latest, setuptools=latest, wheel=latest, via=copy, app_data_dir=C:\Users\Ambarish\AppData\Local\pypa\virtualenv\seed-app-data\v1.0.1) activators BashActivator,BatchActivator,FishActivator,PowerShellActivator,PythonActivator,XonshActivator C:\RISHI\Dev\myDjang>dir Volume in drive C is Windows Volume Serial Number is 0CDC-A763 Directory of C:\RISHI\Dev\myDjang 31-07-2019 21:39 <DIR> . 31-07-2019 21:39 <DIR> .. 16-04-2019 11:20 <DIR> Include 31-07-2019 21:39 <DIR> Lib 28-03-2018 17:07 30,340 LICENSE.txt 31-07-2019 21:40 <DIR> Scripts 31-07-2019 21:39 <DIR> tcl 1 File(s) 30,340 bytes 6 Dir(s) 575,724,306,432 bytes free C:\RISHI\Dev\myDjang>cd Scripts C:\RISHI\Dev\myDjang\Scripts>dir Volume in drive C is Windows Volume Serial Number is 0CDC-A763 Directory of C:\RISHI\Dev\myDjang\Scripts

Rishi – Python Django 31-07-2019 21:40 <DIR> . 31-07-2019 21:40 <DIR> .. 31-07-2019 21:40 2,315 activate 31-07-2019 21:40 883 activate.bat 31-07-2019 21:40 2,038 activate.ps1 31-07-2019 21:40 1,159 activate.xsh 31-07-2019 21:40 1,517 activate_this.py 31-07-2019 21:40 512 deactivate.bat 31-07-2019 21:40 102,783 easy_install-3.6.exe 31-07-2019 21:40 102,783 easy_install.exe 31-07-2019 21:40 102,765 pip.exe 31-07-2019 21:40 102,765 pip3.6.exe 31-07-2019 21:40 102,765 pip3.exe 31-07-2019 21:39 100,504 python.exe 31-07-2019 21:39 58,520 python3.dll 31-07-2019 21:39 3,610,776 python36.dll 31-07-2019 21:39 98,968 pythonw.exe 31-07-2019 21:40 102,761 wheel.exe 16 File(s) 4,493,814 bytes 2 Dir(s) 575,724,306,432 bytes free C:\RISHI\Dev\myDjang\Scripts>activate (myDjang) C:\RISHI\Dev\myDjang\Scripts> (myDjang) C:\RISHI\Dev\myDjang\Scripts>cd .. (myDjang) C:\RISHI\Dev\myDjang>mkdir src (myDjang) C:\RISHI\Dev\myDjang>dir Volume in drive C is Windows Volume Serial Number is 0CDC-A763 Directory of C:\RISHI\Dev\myDjang 31-07-2019 21:43 <DIR> . 31-07-2019 21:43 <DIR> .. 16-04-2019 11:20 <DIR> Include 31-07-2019 21:39 <DIR> Lib 28-03-2018 17:07 30,340 LICENSE.txt 31-07-2019 21:40 <DIR> Scripts 31-07-2019 21:43 <DIR> src 31-07-2019 21:39 <DIR> tcl 1 File(s) 30,340 bytes 7 Dir(s) 575,725,363,200 bytes free (aprDjango) C:\RISHI\Dev\aprDjango\src>pip install django Collecting django Downloading Django-3.0.6-py3-none-any.whl (7.5 MB) | ████████████████████████████████ | 7.5 MB 3.3 MB/s Collecting asgiref~=3.2

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Rishi – Python Django Using cached asgiref-3.2.7-py2.py3-none-any.whl (19 kB) Collecting sqlparse>=0.2.2 Using cached sqlparse-0.3.1-py2.py3-none-any.whl (40 kB) Collecting pytz Using cached pytz-2020.1-py2.py3-none-any.whl (510 kB) Installing collected packages: asgiref, sqlparse, pytz, django Successfully installed asgiref-3.2.7 django-3.0.6 pytz-2020.1 sqlparse-0.3.1 WARNING: You are using pip version 20.0.2; however, version 20.1 is available. You should consider upgrading via the 'C:\RISHI\Dev\aprDjango\Scripts\python.exe -m pip install -- upgrade pip' command. (myDjang) C:\RISHI\Dev\myDjang\ src > (myDjang) C:\RISHI\Dev\myDjang\src >pip freeze Django==2.0.7 pytz==2019.2 (myDjang) C:\RISHI\Dev\myDjang>cd src (myDjang) C:\RISHI\Dev\myDjang\src>django-admin Type 'django-admin help <subcommand>' for help on a specific subcommand. Available subcommands: [django] check compilemessages createcachetable dbshell diffsettings dumpdata flush inspectdb loaddata makemessages makemigrations migrate runserver sendtestemail shell showmigrations sqlflush sqlmigrate sqlsequencereset squashmigrations startapp startproject test testserver Note that only Django core commands are listed as settings are not properly configured (error: Requested setting INSTALLED_APPS, but settings are not configured. You must either define the

Rishi – Python Django environment variable DJANGO_SETTINGS_MODULE or call settings.configure() before accessing settings.). ( myDjang) C:\RISHI\Dev\myDjang\src>django-admin startproject myDjang . (myDjang) C:\RISHI\Dev\myDjang\src>dir Volume in drive C is Windows Volume Serial Number is 0CDC-A763 Directory of C:\RISHI\Dev\myDjang\src 31-07-2019 21:50 <DIR> . 31-07-2019 21:50 <DIR> .. 31-07-2019 21:50 <DIR> myDjang 31-07-2019 21:50 559 manage.py 1 File(s) 559 bytes 3 Dir(s) 575,693,553,664 bytes free (aprDjango) C:\RISHI\Dev\aprDjango\src>python manage.py runserver Watching for file changes with StatReloader Performing system checks... System check identified no issues (0 silenced). You have 17 unapplied migration(s). Your project may not work properly until you apply the migrations for app(s): admin, auth, contenttypes, sessions. Run 'python manage.py migrate' to apply them. May 04, 2020 - 20:42:08 Django version 3.0.6, using settings 'aprDjango.settings' Starting development server at http://127.0.0.1:8000/ Quit the server with CTRL-BREAK. Open second command prompt and execute below command: (septDjango) C:\RISHI\Dev\septDjango\src>python manage.py migrate Operations to perform: Apply all migrations: admin, auth, contenttypes, sessions Running migrations: Applying contenttypes.0001_initial... OK Applying auth.0001_initial... OK Applying admin.0001_initial... OK Applying admin.0002_logentry_remove_auto_add... OK Applying contenttypes.0002_remove_content_type_name... OK Applying auth.0002_alter_permission_name_max_length... OK Applying auth.0003_alter_user_email_max_length... OK Applying auth.0004_alter_user_username_opts... OK Applying auth.0005_alter_user_last_login_null... OK Applying auth.0006_require_contenttypes_0002... OK Applying auth.0007_alter_validators_add_error_messages... OK Applying auth.0008_alter_user_username_max_length... OK

Rishi – Python Django Applying auth.0009_alter_user_last_name_max_length... OK Applying sessions.0001_initial... OK (septDjango) C:\RISHI\Dev\septDjango\src>python manage.py makemigrations No changes detected (myDjang) C:\RISHI\Dev\myDjang\src>python manage.py createsuperuser Username: admin Email address: admin@myDjang.com Password: Password (again): Superuser created successfully. (myDjang) C:\RISHI\Dev\myDjang\src>python manage.py runserver Performing system checks... System check identified no issues (0 silenced). July 31, 2019 - 22:07:54 Django version 2.0.7, using settings 'myDjang.settings' Starting development server at http://127.0.0.1:8000/ Quit the server with CTRL-BREAK. [31/Jul/2019 22:08:08] "POST /admin/login/?next=/admin/ HTTP/1.1" 302 0 [31/Jul/2019 22:08:09] "GET /admin/ HTTP/1.1" 200 2984 [31/Jul/2019 22:08:09] "GET /static/admin/css/dashboard.css HTTP/1.1" 200 412 [31/Jul/2019 22:08:09] "GET /static/admin/css/responsive.css HTTP/1.1" 304 0 [31/Jul/2019 22:08:09] "GET /static/admin/css/base.css HTTP/1.1" 304 0 [31/Jul/2019 22:08:09] "GET /static/admin/css/fonts.css HTTP/1.1" 304 0 [31/Jul/2019 22:08:09] "GET /static/admin/fonts/Roboto-Light-webfont.woff HTTP/1.1" 304 0 [31/Jul/2019 22:08:09] "GET /static/admin/fonts/Roboto-Bold-webfont.woff HTTP/1.1" 304 0 [31/Jul/2019 22:08:09] "GET /static/admin/fonts/Roboto-Regular-webfont.woff HTTP/1.1" 304 0 [31/Jul/2019 22:08:09] "GET /static/admin/img/icon-addlink.svg HTTP/1.1" 200 331 [31/Jul/2019 22:08:09] "GET /static/admin/img/icon-changelink.svg HTTP/1.1" 200 380 [31/Jul/2019 22:08:21] "GET /admin/auth/user/ HTTP/1.1" 200 7089 [31/Jul/2019 22:08:21] "GET /static/admin/css/changelists.css HTTP/1.1" 200 6170 [31/Jul/2019 22:08:21] "GET /admin/jsi18n/ HTTP/1.1" 200 3185 [31/Jul/2019 22:08:22] "GET /static/admin/js/jquery.init.js HTTP/1.1" 200 363 [31/Jul/2019 22:08:22] "GET /static/admin/js/vendor/jquery/jquery.js HTTP/1.1" 200 258648 [31/Jul/2019 22:08:22] "GET /static/admin/js/core.js HTTP/1.1" 200 7134 [31/Jul/2019 22:08:22] "GET /static/admin/js/admin/RelatedObjectLookups.js HTTP/1.1" 200 6897 [31/Jul/2019 22:08:22] "GET /static/admin/js/actions.js HTTP/1.1" 200 6502 [31/Jul/2019 22:08:22] "GET /static/admin/js/prepopulate.js HTTP/1.1" 200 1538 [31/Jul/2019 22:08:22] "GET /static/admin/js/vendor/xregexp/xregexp.js HTTP/1.1" 200 128820 [31/Jul/2019 22:08:22] "GET /static/admin/js/urlify.js HTTP/1.1" 200 8729 [31/Jul/2019 22:08:22] "GET /static/admin/img/search.svg HTTP/1.1" 200 458 [31/Jul/2019 22:08:22] "GET /static/admin/img/icon-yes.svg HTTP/1.1" 200 436 [31/Jul/2019 22:08:22] "GET /static/admin/img/tooltag-add.svg HTTP/1.1" 200 331 [31/Jul/2019 22:08:22] "GET /static/admin/img/sorting-icons.svg HTTP/1.1" 200 1097 [31/Jul/2019 22:08:40] "GET /admin/ HTTP/1.1" 200 2984 [31/Jul/2019 22:08:42] "GET /admin/auth/group/ HTTP/1.1" 200 3584 [31/Jul/2019 22:08:42] "GET /admin/jsi18n/ HTTP/1.1" 200 3185

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Rishi – Python Django [31/Jul/2019 22:08:46] "GET /admin/ HTTP/1.1" 200 2984 Performing system checks... System check identified no issues (0 silenced). July 31, 2019 - 22:17:44 Django version 2.0.7, using settings 'myDjang.settings' Starting development server at http://127.0.0.1:8000/ Quit the server with CTRL-BREAK. On Another Command Prompt ( myDjang) C:\RISHI\Dev\myDjang\src>python manage.py makemigrations (myDjang) C:\RISHI\Dev\myDjang\src>python manage.py migrate (myDjang) C:\RISHI\Dev\myDjang\src> https://docs.djangoproject.com/en/2.2/ref/models/fields/ Important note for you, download Subline text: https://www.sublimetext.com/3 Use this option to navigate to Virtual environment folder and open the project here. Understanding Settings: BASE_DIR – this is where your project is. DEBUG = True → Very important for development. Don’t deploy this in production INSTALLED_APPS → think of apps more like a component you are going to develop ROOT_URLCONF → Context Root of application TEMPLATES → Configure your HTML pages here. We will learn more along the way DATABASES → Django by default maps sql lite 3. You can map your database instance here

Rishi – Python Django AUTH_PASSWORD_VALIDATORS → Password authenticators Creating your Own App: Creating your own applications (Apps): ( myDjango) C:\RISHI\Dev\myDjango\src>python manage.py startapp products Product app should do only product related things. It should be concise to product functionality. first: That’s it. Now go to settings and add it in Installed Apps. Every time you change a model or create a new model, run below commands (myDjango) C:\RISHI\Dev\myDjango\src>python manage.py makemigrations Migrations for 'products': products\migrations\0001_initial.py - Create model Product (myDjango) C:\RISHI\Dev\myDjango\src>python manage.py migrate Apply all migrations: admin, auth, contenttypes, products, sessions Running migrations: Applying products.0001_initial... OK (myDjango) C:\RISHI\Dev\myDjango\src> Now go to admin.py and make these changes:

Rishi – Python Django Now start the server if its not already running and open Admin page. (myDjango) C:\RISHI\Dev\myDjango\src>python manage.py runserver Performing system checks... System check identified no issues (0 silenced). August 01, 2019 - 10:49:38 Django version 2.0.7, using settings 'myDjango.settings' Starting development server at http://127.0.0.1:8000/ Quit the server with CTRL-BREAK. Login to Admin page and see new Product got added on Page. Can you add new products? Check it out. Let’s change the Model: We will use these model fields https://docs.djangoproject.com/en/2.2/ref/models/fields/ You may not need to delete DB, please try the steps directly: (septDjango) C:\RISHI\Dev\septDjango\src>python manage.py makemigrations You are trying to add a non-nullable field 'promoted' to product without a default; we can't do that (the database needs something to populate existing rows). Please select a fix: 1) Provide a one-off default now (will be set on all existing rows with a null value for this column) 2) Quit, and let me add a default in models.py Select an option: 1 Please enter the default value now, as valid Python The datetime and django.utils.timezone modules are available, so you can do e.g. timezone.now Type 'exit' to exit this prompt

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Rishi – Python Django >>> False Migrations for 'products': products\migrations\0002_auto_20190910_2055.py - Add field promoted to product - Add field summary to product - Alter field description on product - Alter field price on product - Alter field title on product (septDjango) C:\RISHI\Dev\septDjango\src>python manage.py migrate Operations to perform: Apply all migrations: admin, auth, contenttypes, products, sessions Running migrations: Applying products.0002_auto_20190910_2055... OK Use this only when above options are not working. If above commands doesn’t work.. then do below steps: 1. Stop the server 2. Delete all the files in migrations folder 3. Delete pyCache. You can keep init. 4. Delete sql.lite DB file Lets make the change in Model now.: Now before making migrations, you need to create user, you need to recreate it.. why? Remember you have deleted the database. (myDjango) C:\RISHI\Dev\myDjango\src>python manage.py makemigrations Migrations for 'products': products\migrations\0001_initial.py - Create model Product (myDjango) C:\RISHI\Dev\myDjango\src>python manage.py migrate Operations to perform: Apply all migrations: admin, auth, contenttypes, products, sessions Running migrations: Applying products.0001_initial... OK Now login to admin → navigate to create Product and enjoy the new view. Have you need Boolean Field?

Rishi – Python Django Handling Runtime Model Changes: Make some changes in Model now: Now, Database don’t know how to handle this new field. What should be the value of this field for previous entries. It will ask you same question while migrating. (myDjango) C:\RISHI\Dev\myDjango\src>python manage.py makemigrations You are trying to add a non-nullable field 'newField' to product without a default; we can't do that (the database needs something to populate existing rows). Please select a fix: 1) Provide a one-off default now (will be set on all existing rows with a null value for this column) 2) Quit, and let me add a default in models.py Select an option: Give option as you think. Option 2 is better when you want to go back and enter some default value. Here we will use option 1 Select an option: 1 Please enter the default value now, as valid Python The datetime and django.utils.timezone modules are available, so you can do e.g. timezone.now Type 'exit' to exit this prompt >>> True Migrations for 'products': products\migrations\0002_auto_20190801_1140.py - Add field newField to product - Alter field Summary on product Observe migrations folder. Check how Django handled this migration.

Rishi – Python Django Now, go ahead and add migrate, then start server and check previous products. (myDjango) C:\RISHI\Dev\myDjango\src>python manage.py migrate Operations to perform: Apply all migrations: admin, auth, contenttypes, products, sessions Running migrations: Applying products.0002_auto_20190801_1140... OK (myDjango) C:\RISHI\Dev\myDjango\src>python manage.py runserver Performing system checks... System check identified no issues (0 silenced). August 01, 2019 - 11:43:27 Django version 2.0.7, using settings 'myDjango.settings' Starting development server at http://127.0.0.1:8000/ Quit the server with CTRL-BREAK blank = True or null = True? Which one to use . Blank is about Field on Web Page. Null Is about database. If Blank is false, you cannot leave the field blank.

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Rishi – Python Django Default Home Page to Custom Home Page Before starting this section, just do this for me: 1. Create a new app called “pages” 2. Add your new module in settings. If you don’t remember how to do it, please revise the videos. 3. Go to pages app and open views.py. Add below code. 4. Now go to myDjango folder and open url.py – as mentioned in comments above, please add our view here 5. Now hit the URL: http://localhost:8000/ URL Routing and Requests: Try access URL with http://localhost:8000/home/  Observe if anything changes? Assignment: Can you add Contact page like this? Lets do it. Add as many view as you want. Play around with it.

Rishi – Python Django What else we can do with views? Can we access Request Parameters coming in web request. Lets go to HTML Page: add method to views.py. Create HTML page HTML Page in template folder. Create templates folder directly under src.

Rishi – Python Django Go to settings and add this directory in DIRS in TEMPLATES section. Run this project now. See if you get web page. But the path given here will not work on your machine if I send you this code. So what should we do? Lets use BASE_DIR Assignment 2: Can you create more html pages now like – about.html, contact.html, home.html and point it to web address? Please try and let me know.

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Rishi – Python Django Django Template Inheritance. You can use UserModel in template engine. Lets try this for a simple thing like request.user . Check the response now. You might need to use something common across all html pages, lets say a navigation bar or some meta data. So lets create a page called in template to handle this. Now use this block content in contact.html: Now refresh the output screen and check the output. Can you make similar change in other html pages you created? Assignment 3: Remember {% block content %} → block is Django stuff while “content” is my variable. You can change that too. Just make sure you are using same variable everywhere. Wait.. can you add more blocks then? Answer is – YES. Can you try that? Please do.

Rishi – Python Django Include template tag: Now I want a navbar in all pages. So do I have to add it in my base.html? YES. But that make base.html really heavy in UI related entities. So lets do this: I am creating another html page called navbar.html Now use include to use this html page in base.html Load contact.html now. See the change. Rendering Context in a Template: What we really need on web page is Data from database isn’t it? For Django, User Page = template + context . What do I mean by that? Remember that empty dictionary we passed to html page? Add something in it now. Can we add a List in context? How can we show that on screen as HTML List?

Rishi – Python Django Can we use Conditions in Templates? What is this |add:2  this is built in template tag filter. Lets check Django page for this. Search for “ Built- in filter reference” https://docs.djangoproject.com/en/2.2/ref/templates/builtins/ I strongly recommend you go through entire set and try few options.

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Rishi – Python Django Getting Data from DB: Step 1: Open views from product app and create a view method. You access Product object with Product.objects.get(id=N) Add this view in URLs. Create product/details.html page in templates folder. But then, why are we adding such a complicated context. Can we make it simple?

Rishi – Python Django Now I am moving my template into App itself. How? Lets create template folder under product app. This make my code more modular. Isn ’ t it? Django Forms: Aim is to create Product Form, which will take user inputs to create record in DB. First Step to create forms.py and create model Form like below: We have to load this form from view. So add method:

Rishi – Python Django Now complete product_create.html Understand csrf_token as a part of security. We will discuss it in detail in class. Also, forms.as_p makes entire form as <P> tags. Next step? Add this view in URL. Restart the server and check the code. If you see any error, revise the steps and look for mistake. Still can’t get it? Email me: rishi.h2kinfosys@gmail.com Form Validation Method: First I want to tell you that you can override every field in model class. Can we try one?

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Rishi – Python Django Lets talk about widgets and attributes. With this code, you have overridden the form coming from Model by default. Now how validation works? Suppose I want to check my title field has “ H2K ” letters, I can write a specific method with name clean_<my_field_name>(self) Of course, if title is not valid, you can raise a ValidationError which will be shown on screen. So will you write email validation for me? Setting Initial Data to Fields: Use initial_data dictionary to set initial data. Please see the example below:

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Rishi – Python Django You can also load Database entry to set as initial value: Dynamic Data Loading: Dynamically pass the data with URL: Handle this in method which shows view: But what if someone sends an ID which doesn’t exists in DB? Handle DoesNotExist / 404 You can achieve 404 Handling with get_object_or_404() or Http404 – see the code below:

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Django Materials - Rishi Python - May 2020

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