learning-django

Learning Django from YouTube

Just one of the things I'm learning. https://github.com/hchiam/learning

My older repo: https://github.com/hchiam/djangoApp

Boilerplate code: https://github.com/hchiam/Django-REST-Boilerplate

What's next are my notes from following thenewboston's YouTube tutorial series:

get django

• Have Anaconda installed? Do this: conda install django

create project "website"

• django-admin startproject website (generates the base required files for any django project)
• (Note to self: to remember what files do, read names as if reading directory paths.)
• (Note to self: we're usually going to use website/settings.py and website/urls.py)
• Navigate to website folder so that you see manage.py and website folder.
• python manage.py runserver
  • You might have to do something like this beforehand: export PYTHONPATH=/usr/local/lib/python3.6/site-packages
  • To make it permanent (i.e. not have to type that every time), add export PYTHONPATH=/usr/local/lib/python3.6/site-packages to your .bash_profile file (open ~/.bash_profile).
• http://127.0.0.1:8000/
• Hit Ctrl+c to stop the server.

create "app"

• (Note to self: "apps" are like subdirectories in a URL, like different tabs.)
• (Note to self: each "app" should have a one-liner of what it does.)
• python manage.py startapp app1
• (Note: migrations folder is for connecting website to database.)
• (Note: admin.py has admin functionality built in.)
• (Note: apps.py is basically app settings.)
• (Note: models.py is app database model setup.)
• (Note: views.py are basically python functions for requests/responses.)
• Create a urls.py file inside app1.
• Make website/urls.py include app1/urls.py.
• Make app1/urls.py identify a request in the URL and call a function in app1/views.py.
• Make a corresponding response function (in app1/views.py) to the request.
• http://127.0.0.1:8000/app1
• (Note to self: website/website/urls.py --> urlpatterns --> app1/urls.py --> views.py function request response)

connect/synchronize database

• (Note: db.sqlite3 was automagically created as a default database for testing. Can change to MyQSL later.)
• python manage.py migrate (to synchronize code with database)
  • website/settings.py INSTALLED_APPS --> checks app directories for required tables

create & activate models (how you want to store your data; tables and columns)

• (Note: in Django, python class variables get converted to database columns.)
• Create a class ("table") and variables ("columns") in app1/models.py, while specifying data types.
• Make website/settings.py INSTALLED_APPS include app1/apps.py App1Config() as 'app1.apps.App1Config'.
• Remember to synchronize database with models! python manage.py makemigrations app1.
• (Optional to see what the migration does:)
  • (Migration = change to database.)
  • (python manage.py sqlmigrate app1 0001 shows changes that converts the model into an SQL file.)
  • (Note the "0001_initial.py".)
• python manage.py migrate (so databased synched with code)
• python manage.py runserver
• (Note to self: website/website/settings.py INSTALLED_APPS --> models.py --> check classes, variables to synch database)

Remember 3 steps when you want to udpate changes to databases:

1. change website/models.py
2. python manage.py makemigrations app1
3. python manage.py migrate

database API

• python manage.py shell (and now you can write database commands!)
• Then try these commands, one-by-one:

from app1.models import Album, Song
Album.objects.all()
a = Album(artist="the new boston", album_title="Red", genre="Country", album_logo="https://thenewboston.com/photos/users/2/original/e1ee187e9e0225ba124ba1c7c9dbfa56.png")
a.save()
a.artist
a.album_title
a.id # this is the same
a.pk # as this
b = Album()
b.artist = "artist2"
b.album_title = 'title2'
b.genre = 'Jazz'
b.album_logo = 'https://www.wikipedia.org/portal/wikipedia.org/assets/img/[email protected]'
b.save()
a.artist
b.artist
b.album_title = "High School"
b.album_title
exit()

filtering database results (video #10)

first, set up so filtered results show basic info

• Make app1/models.py Album class to have a __str__() function to customize the shell output representation of an Album.
• python manage.py shell
• from app1.models import Album, Song
• Album.objects.all() should output a list of strings for album titles/artists, for example, instead of just a list of Album objects.
• (We didn't do save() for that last title, so the last album title udpate didn't actually get saved in the database.)
• (I accidentally created a duplicate object. I did Album.objects.all().delete() to delete all records (and hence remote duplicates) and then Album.objects.all() again to check that it actually cleared everything.)

actually do the filtering

• Album.objects.filter(id=5) to filter by finding result(s) with id=5 (there should only be one or none)
• Album.objects.filter(id=6)
• Album.objects.filter(artist__startswith='the ') using double underscore to get entries with artists starting with 'the '

admin interface

• python manage.py createsuperuser to create admin
• set username, email, password
• http://127.0.0.1:8000/admin/
• log in
• Go to app1/admin.py to set up admin access to be able to see and edit databases.
  • Register Album in admin site.
• http://127.0.0.1:8000/admin/ (refresh)
  • You should see App1.
  • You can click on Albums to see the records.
  • You can click on a record to edit its contents.

create another view

• (Note: view = function that takes a request and returns html)
• (Note: each view is linked to a URL pattern.)
• (Note: each URL is linked to an HTML response/page.)
• Edit app1/urls.py (to find pattern matches for requests) and app1/views.py (to define actions for requests).

connect request/response to database

• Make app1/views.py import Album from .models
• In app1/views.py, you can type all_albums = Album.objects.all(), just like in the shell!
• http://127.0.0.1:8000/app1/ to see all albums
  • (Try going to details pages too.)
• (Note: we want to be able to separate the html from the python code for "separation of concerns".)

create template

• (Note: Use templates to separate front-end HTMl/CSS files etc. from back-end Python files.)
• Create template HTML file app1/templates/app1/index.html:
  • Navigate to website (sub)folder (the one with manage.py in it).
  • mkdir app1/templates/
  • mkdir app1/templates/app1
  • touch app1/templates/app1/index.html
  • Create template code (see index.html), using html but also a for loop in "kinda python" code inside that html file.
• Open and write in app1/templates/app1/index.html
• Have app1/views.py make use of that template:
  • from django.template import loader to be able to load separate template files.
    • (Note: don't need this in later shortcut tutorial.)
  • Get database data, get template, get data to put into template, return filled template as HTML response.
• http://127.0.0.1:8000/app1/ to see it in action.

shortcut for load-render template

• from django.shortcuts import render in app1/views.py so you can use render()
• http://127.0.0.1:8000/app1/

activate 404 HTTP error page + message

• Create and make template HTML file app1/templates/app1/detail.html
• app1/views.py from django.http import Http404 and edit detail().
• Go to http://127.0.0.1:8000/app1/ and try clicking on albums to see details.
• Try going to 127.0.0.1:8000/app1/54 (or an id that doesn't exist).

add entries to database

• (We're going to add a song to an album.)
• Add to app1/models.py class Song the function __str__().
  • (Note: don't have to migrate / synch database because not adding attributes / columns.)
• Add to app1/admin.py import Song model and register Song model in admin site.
• http://127.0.0.1:8000/admin/ and check Songs

and then create song, set attributes, and save it:

python manage.py shell
from app1.models import Album, Song
album1 = Album.objects.get(id=5)
album1.artist # should return 'the new boston'
song = Song() # requires album, file_type, song_title
song.album = album1
song.file_type = 'mp3'
song.song_title = 'some title'
song.save()

• http://127.0.0.1:8000/admin/app1/song/ should show that song in there.

oooor do that in one step with the create function:

(continuing with the same shell)

album1.song_set.all() # to see it so far
album1.song_set.create(song_title='I love bacon', file_type='mp3') # album already specified
album1.song_set.create(song_title='ice cream', file_type='mp3') # album already specified

• http://127.0.0.1:8000/admin/app1/song/ should show those new songs in there.

song = album1.song_set.create(song_title='hamburger', file_type='mp3') # make use of returned reference to that song
song.album
song.song_title
album1.song_set.all() # to see all songs in album1
album1.song_set.count() # gets size of set

design the details.html template

• Edit app1/templates/app1/detail.html
• Refer to app1/models.py for the classes and corresponding variables.
• http://127.0.0.1:8000/app1/5/ should now show the image and other info available.

remove hardcoded URLs (i.e. completely dynamic URLs)

• (I.e. make URLs completely dynamic, in case website structure changes.)
• (Note: app1/urls.py is a centralized place to edit the URL structure of the website.)
  • (Note: The ='index' in url(r'...', views...., name='index'), gives the URL pattern the name 'index', so other files can refer to it.)
• Edit app1/templates/app1/index.html
  • href="{% url 'detail' album.id %}/" means to use URL pattern named detail and give it parameter variable album.id
• http://127.0.0.1:8000/app1/ and try going to one of the albums.

namespaces / pattern reuse

• (Example: so we can reuse 'detail' pattern in both music/detail and video/detail, but need to specify which one.)
• Add app namespace app_name = 'app1' to app1/urls.py
• Use that namespace in app1/templates/index.html:
  • href="{% url 'detail' album.id %}" becomes href="{% url 'app1:detail' album.id %}".
  • I.e. 'detail' becomes 'app1:detail'. Means to look for app1 detail pattern instead of just a generic detail pattern.
• (Note to self: can now reuse patterns.)

HTTP 404 shortcut

• Import get_object_or_404 in app1/views.py
• album = get_object_or_404(Album, pk=album_id) replaces a whole try/except statement in detail().

create form (in the easiest way to understand anyways)

• Make app1/models.py Song class have another attribute: is_favourite
• Make change file: python manage.py makemigrations app1
• Apply change to database: python manage.py migrate
• Restart server: Ctrl+C and then python manage.py runserver (in that separate Terminal).
• Refresh a view like http://127.0.0.1:8000/app1/5/ to see no errors.

You might want to have a URL that doesn't link to a template, like a "logging out" page that runs and then automatically redirects to another page.

• App a favourite URLs pattern in app1/urls.py

Actually make the form:

• Create a <form> in app1/templates/app1/detail.html view
  • action="..." is the URL pattern to send data to: action="{% url 'app1:favourite' album.id %}"
  • method="post"
  • csrf_token is for security CSRF
  • Loop through form elements. {{ forloop.counter }} auto-increments.
  • name="..." enables reference in the code.
• (Note: detail.html's action will go to urls.py to find the URL pattern for app1:favourite)
• (Note: URL pattern for app1:favourite will go to views.py to find favourite())
• Add function favourite() in app1/views.py
• Refresh a view like http://127.0.0.1:8000/app1/5/.
• Try favouriting a couple songs. (You can see updates in the admin page too!)
• (Note to self: detail.html loop to generate form --> associate each song with song.id --> user selects song + hits favourite --> app1:favourite --> urls.py views.favourite --> views.py favourite())
• (Note to self: song.id --> selected_song.is_favourite --> selected_song.save() --> redirect back to same page as if didn't leave)

add style with static files

Example: https://github.com/buckyroberts/Viberr

• (We're going to include CSS into the templates.)
• Create app1/static/app1/ and in that, /images folder and style.css file.
• Create CSS file app1/static/app1/style.css:
  • Navigate to website (sub)folder (the one with manage.py in it).
  • mkdir app1/static/
  • mkdir app1/static/app1
  • mkdir app1/static/app1/images (and put a background.png in it)
  • touch app1/static/app1/style.css
  • Create CSS code (see style.css).
• Include that CSS file style.css in index.html:
  • app1/templates/app1/index.html
  • Load path to static files (like style sheet): {% load staticfiles %}.
  • Load specific files you need like style.css: href="{% static 'app1/style.css' %}" is literally for /static/
• http://127.0.0.1:8000/app1/ to see the changed background image.

add Bootstrap style

• Include <link> in app1/templates/app1/index.html
• Make changes as desired.

build up more of navigation menu

• app1/templates/index.html
  • more for style: classes
  • more for function: type, data-target, role, etc.
• Using: bootstrap css and js, google font, jquery js, and static file ('local')
• Make sure app1/static/app1/style.css is being used after bootstrap.
• Edit app1/static/app1/style.css
• Try resizing http://127.0.0.1:8000/app1/ to small width to see header's 3 icon-bars for expanding the navigation menu.
• Test out the navigation menu's buttons and search form.

create base template (e.g. consistent navigation bar and styling)

• Create a new html file app1/templates/app1/base.html
  • Remove the stylesheets and scripts and navbar from app1/templates/app1/index.html and move those into app1/templates/app1/base.html where appropriate (these will be things you'll need on every page).
  • Create a "block" to hold a "customizable area" in that base template: example: a block called "body": {% block body %} {% endblock %}
• Use that template by including it in the other .html template files: {% extends 'app1/base.html' %}
• Tell the base template the "custom area": {% block body %} (your original .html code here) {% endblock %}
• (Note to self: you can have multiple "block" areas in the same base.html and in the files that use it!)
  • You can <title>{% block title %}default text here{% endblock %}</title> in the header section to overwrite!

generic views (to write less code with classes, instead of functions in views.py)

• (Note to self: website pages come in 2 basic patterns: a list of objects or details on one object. Example: Youtube=list of videos --> go to video --> video details)
  • (Django automates generating these 2 basic patterns: list generic view and detail generic view.)
• Rewrite app1/views.py to use classes instead of functions, and save a lot of code.
  • (Note: query results are put into a variable named object_list by default.)
  • IndexView(generic.ListView)
  • DetailView(generic.DetailView)
• Rewrite app1/urls.py urlpatterns to use the new classes (and pk for the detail view).
  • views.IndexView.as_view()
  • views.DetailView.as_view()
• http://127.0.0.1:8000/app1/ should have no albums to show because need to use object_list in your views.py code, or rename it to store view data in a variable for template to use, e.g.: context_object_name = 'all_albums' in views.py.
• http://127.0.0.1:8000/app1/ should work now, either way.
• (Note: in video 29 on generic views, detail.html and index.html have the "favourite"-related things removed.)

(before the model form tutorial videos 30-31)

https://github.com/Ananthu/Django-thenewboston-youTube-classes

model forms - CreateView part (videos 30-31)

• (Note: model forms help generate form html and also form validation.)
• In app1/models.py:
  • Add from django.core.urlresolvers import reverse
  • Create get_absolute_url() to get the new url for the Album created by the form.
• In app1/views.py:
  • Add from django.views.generic.edit import CreateView, UpdateView, DeleteView
  • Create class AlbumCreate(CreateView) to create a new Album from the form.
• In app1/urls.py:
  • Assign a new URL pattern corresponding to the new view in views.py (namely, AlbumCreate).
• Create template app1/album_form.html for it to go to (naming format: "modelnameinlowercase_form.html").
  • (Note: include 'app1/templates/app1/form-template.html' is the generic form template to keep code DRY.)
• Create app1/templates/app1/form-template.html
• Add link to that navbar button "Add Album" in base.html so user can get to the form.
  • (Note: Replace '#'. Make sure the link matches the URL format in urls.py: href="{% url 'app1:album-add' %}")
• http://127.0.0.1:8000/app1/
  • Click on "Add Album" to see the new album form!
  • Try not entering anything and hitting Submit --> should get errors for required fields using field.errors.
  • Try actually filling everything in and submitting --> shoudl get redirected to details view of the new album.