Mitesh
- http://localhost:8000/rilblog/
-----List of all blog posts - http://localhost:8000/posts/details/1/
----- Blog posts & comments
- http://localhost:8000/admin/
----- Create new users - http://localhost:8000/admin/rilblog/posts/
----- Users can create a Blog here - http://localhost:8000/admin/rilblog/comments/
----- Logged in user can add Comments here
- Key is the "id" (Primary Key) of the Blog
post = Posts.objects.get(id=id)
detail_dict = {"title":(post.title), "body":post.body, "created_at":str(post.created_at)}
setkey = cache.set(id, json.dumps(detail_dict), timeout=CACHE_TTL)
- For get, i have created a generic object and put the fields and values after fetching them from Redis:
if cache.__contains__(id):
data_dict = ast.literal_eval(data_str)
class Object(object):
pass
a = Object()
a.title = data_dict['title']
a.body = data_dict['body']
a.created_at = data_dict['created_at']
context = {'post': a, 'comments': comment }
return render(request, 'posts/details.html', context)
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I have used 2 Db Models for this application
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Posts -- For storing the individual posts created by users
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Comments -- For storing the comments for each post(FK-postid) (1-M)relationship.
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- install python v3.6.5 - from the website msi installer
- install django v2.0.6 - pip install Django==2.0.6
--Setup Python 3 on Ubuntu 18.04 LTS--
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On my Ubuntu machine, there are two versions of python available, python2.7 as default python version and python3.
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In this step, we will change the default python version to python 3.
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Check the python version: $ python --version
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So the default python is 2.7 at the moment.
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Next, change the default python to python version 3 with the 'update-alternatives' command: $ update-alternatives --install /usr/bin/python python /usr/bin/python3 1
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Now check again the python version: $ python --version
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And you will get python 3.6 as a default python on the system.
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Run command below to install pip for python 3. $sudo apt install python3-pip -y
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The installation will add a new binary file called 'pip3'. To make it easier to use pip, I will create a symlink for pip3 to pip: $ which pip3 $ ln -s /usr/bin/pip3 /usr/bin/pip
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Now check the version :
$pip --version $ pip install Django -
After the installation is complete, check the Django version with the command below: $ python
import django print(django.get_version())
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Q) How to use Redis in Django? A) Django uses django-redis to execute commands in Redis. $ pip install django-redis (Output wil be something like this: Installing collected packages: pytz, Django, redis, django-redis Successfully installed Django-2.0.6 django-redis-4.9.0 pytz-2018.4 redis-2.10.6 )
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Q) How to install the Redis server? A) 1. $ sudo apt-get install redis-server (First install redis server) 2. $ redis-server (Run the Redis server .) 3. $ redis-cli ping (We can check whether redis-server is running or not by the following command:) PONG (If we receive this output the redis server is running okay)
SETUP ECLIPSE FOR DJANGO PROJECT : 3. install pydev in eclipse oxygen 4. Preferences -> pydev -> interpreters -> python interpreters : give the location of the exe of python version 5. import all libs in PYTHONPATH
Creating New Application :
1. python manage.py startapp <nameofapp>
START SERVER :
- How to create a superuser in Django ?
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cd C:\Users\neo\blogprojectril
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python manage.py createsuperuser (neo, [email protected], 231513mitesh) (mitz, [email protected], 88215mitesh) (tiger, [email protected] , 231513mitesh )
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cd C:\Users\neo\blogprojectril
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python .\manage.py runserver
STARTING APPS IN DJANGO :
- cd C:\Users\neo\blogprojectril
- python .\manage.py startapp
Creating Model for Database tables creation :
- create classes in models.py for tables.
- python manage.py makemigrations rilblog -- Creates a migration file in the migrations folder in the app
- python manage.py migrate -- making it available for all stuffs in the project.
Q) How table from models will show in admin pannel? A) in the app , in the admin.py add: admin.site.register()
To access those tables from the database :
- python manage.py shell
-- to access the project's shell terminal >>> from <appname>.models import <tablename1, tablename2, ...><tablename>.objects.all() -- for getting the no. of objects in table
Either: 4. a = (field= "value",field= "value",field= "value",field= "value") -- to insert a new row 5. a.save() -- now in shells memory , to save from shells memory to the database Or: 4. a = user() 5. a.user_name = "John Abrahim"
Q) How to add Foreign key in another table from shell ? A) b.post_id = a(id=1)
Q) How to format Output which is not useful by default?:>>> user.objects.all() >>> <QuerySet [<user: user object (1)>]>
- def str (self): return (self.<field_name>) -- in each class for a table in model u have to do this.
Q) How to filter the data from the table? A) .objects.filter(id = 1) -- for getting the no. of objects in table
Q) How to access tables from the admin page : A) from .models import admin.site.register()
Q) How to Delete database tables ? A) For a quick resolve (if you don't care about losing your tables/data), correct your models.py file with the desired data types, delete the Migration folder and db.SQLite3 file, then re-run the following commands: python manage.py migrate python manage.py makemigrations python manage.py migrateIGER python manage.py createsuperuser (to create an admin user/pswd to manage admin page) python manage.py runserver
Q) How to update a field in database ? A) >>> from django.db.models import F # F gives the Fieldvalue of any field we want and then i can perform operations on it >>> Comments.objects.filter(id = 4).update(user=F("user")+4)
Q) What is the PYTHONPATH environment variable? A) The PYTHONPATH environment variable is the list of folders that the import statement will look through when attempting to resolve a module name.
Q) How to set the PYTHONPATH environment variable on Windows XP, Vista, Windows 7, etc? A) For Windows the PYTHONPATH is set in the windows registry. -> Run regedit - First, open up �Run� from the start menu (Ctrl + R). -> Browse to the PythonPath folder - Browse to HKEY_LOCAL_MACHINE -> SOFTWARE -> Python -> PythonCore -> [ Version Number ] -> PythonPath.(Don't alter the pythonpath you see here.) -> Create new key - Right click the PythonPath folder and select New -> Key (Name it what you like.) -> Select the new folder and right click the one blank value sitting on the right side of the screen and select Modify. For the value field, add your new paths separated by � ; � -> Run python and try an import.