मॉडल और माइग्रेशन

from django.db import models

class Post(models.Model):
    title = models.CharField(max_length=200)
print('Post model defined')

from django.db import models

class Post(models.Model):
    title = models.CharField(max_length=200)
    body = models.TextField()
    views = models.IntegerField(default=0)
print('Fields map to columns')

from django.db import models

class Post(models.Model):
    title = models.CharField(max_length=200)
    # 'id' is added automatically
print('id field is automatic')

from django.db import models

class Post(models.Model):
    title = models.CharField(max_length=200, unique=True)
    published = models.BooleanField(default=False)
    subtitle = models.CharField(max_length=200, blank=True)
print('Options refine each field')

from django.db import models

class Post(models.Model):
    title = models.CharField(max_length=200)
    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)
print('Timestamps set automatically')

from django.db import models

class Author(models.Model):
    name = models.CharField(max_length=100)

class Post(models.Model):
    author = models.ForeignKey(Author, on_delete=models.CASCADE)
print('ForeignKey links Post to Author')

# Migrations record schema changes over time
# so the database matches your models
print('Migrations track schema changes')

# python manage.py makemigrations
# -> blog/migrations/0001_initial.py
print('makemigrations writes migration files')

# python manage.py migrate
# -> Applying blog.0001_initial... OK
print('migrate applies changes to the DB')

# 1. Change models.py
# 2. python manage.py makemigrations
# 3. python manage.py migrate
print('Edit, make, migrate')

# Post.objects.all()
# Post.objects.filter(published=True)
# Post.objects.get(id=1)
# Post.objects.create(title='Hello')
print('objects is the query manager')