03models.md

Django Models

A model in Django is a Python Class that represent database table. Each attribute in the model represent field in that table.

How Models Work

• Django use ORM [Object Relational Mapping], which allows you to interact with database using python code instead of SQL.
• Models Define Structure of database, Django automatically create SQL to create database tables and interact with data.

How To Create

Lets suppose we just create blog app in our project. Go to 'yourappname/models.py' and paste the code:

from django.db import models

# Create your models here.
class Post(models.Model):
    title = models.CharField(max_length=100)
    content = models.TextField()
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    def __str__(self):
        return self.title

Migration

• Migratons is Django way of applying change to database schea.
• When you define or update model, you create migration to reflect those changes in the database.

Create Migration

python manage.py makemigrations

This will generate migration file in your apps migration directory.

Apply Migration

• To apply the migration and update in database run:

python manage.py migrate

This will automaticaly create necessary database table based on your model defination.

Register Mode To Admin Site

Go to admin.py in your app directory.

from django.contrib import admin
from .models import Post

# Register your models here.
admin.site.register(Post)

Create Superuser

To create superuser use this command:

python manage.py createsuperuser

Now enter username, password, email and open http://127.0.0.1:8000/admin/

• Enter your username and password
• Now you can add, update, delete, view post.

Django ORM

Django ORM allows youu to interfact with database using Python Code. To start: Type

python manage.py shell

Create a New Post

from blog.models import Post
post = Post.objects.create(title="Hello", content="From Terminal")
print(post)

View Post

• All

from blog.models import Post
posts = Post.objects.all()

• Single Post

from blog.models import Post
post = Post.objects.get(id=1)

Update

from blog.models import Post
post = Post.objects.get(id=1)
post.title = "My New Title"
post.save()

Delete

from blog.models import Post
post = Post.objects.get(id=3)
post.delete()

QuerySet Method and Filters

from blog.models import Post
postsasc= Post.objects.all().order_by('created_at') # Asc
postsdesc= Post.objects.all().order_by('-created_at') #Desc
first_five_post= Post.objects.all().[:5]
count = Post.objects().all().count()

How to Add Image In Models

from django.db import models

# Create your models here.
class Blog(models.Model):
    title = models.CharField(max_length=100)
    description = models.TextField()
    date = models.DateField(auto_now_add=True)
    updated = models.DateField(auto_now=True)
    image = models.ImageField(upload_to='blog/images/') # Add this line

    def __str__(self):
        return self.title

In post.html

 <img height="500" width="700" src="{{blog.image.url}}" alt="{{blog.title}}">

In your setting.py in project directory

import os
MEDIA_URL = '/media/'
MEDIA_ROOT = os.path.join(BASE_DIR, 'media')

In your app urls.py

from django.conf import settings
from django.conf.urls.static import static

urlpatterns = [
    path('admin/', admin.site.urls),
    path('', include('blog.urls')),
] + static(settings.MEDIA_URL, document_root=settings.MEDIA_ROOT)

or

if settings.DEBUG:
    urlpatterns += static(settings.MEDIA_URL, document_root=settings.MEDIA_ROOT)