[Django] ORM - Create, Update, Delete 문 (1:다, 다:다) Model 내에 ForeignKey 와 ManyToManyField

우선 Models.py 의 소스이다.

 

 

from django.db import models
 
class Blog(models.Model):
    name = models.CharField(max_length=100)
    tagline = models.TextField()
 
    def __str__(self):
        return self.name
 
 
class Author(models.Model):
    name = models.CharField(max_length=200)
    email = models.EmailField()
 
    def __str__(self):
        return self.name
 
 
class Entry(models.Model):
    blog = models.ForeignKey(Blog, on_delete=models.CASCADE)
    headline = models.CharField(max_length=255)
    body_text = models.TextField()
    pub_date = models.dateField()
    mod_date = models.dateField()
    authors = models.ManyToManyField(Author)
    number_of_comments = models.IntegerField()
    number_of_pingbacks = models.IntegerField()
    raging = models.IntegerField()
 
    def __str__(self):
        return self.headline
 

위에서 중요하게 볼 부분은 20라인 ForeignKey 와 25라인의 ManyToManyField 부분이다.

 

 

1. Create 문

(1) 클래스 객체를 만들어서 save() 함수를 실행

from blog.models import Blog
 
b = Blog(name='Beatles Blog', tagline='All the latest Beatles news.')
b = save()

 

(2) create() 함수를 이용

 

p = Blog.objects.create(name='Beatles Blog', tagline='All the latest Beatles news.')

 

https://docs.djangoproject.com/en/3.1/ref/models/querysets/#django.db.models.query.QuerySet.create

QuerySet API reference | Django documentation | Django

 

 

2. Update 문

 

b.name = 'Lee'
b.save()

 

(1) ForeignKey 필드 업데이트

 

from blog.models import Blog, Entry
 
entry = Entry.objects.get(pk=1)
cheese_blog = Blog.objects.get(name='Chedar Talk')
entry.blog = cheese_blog
entry.save()
 

 

(2) ManyToMany 필드 업데이트 - add() 이용

 

from blog.models import Author
joe = Author.objects.create(name='Joe')
entry.authors.add(joe)
 

 

한꺼번에 add() 이용도 가능하다.

 

john = Author.objects.create(name='John')
paul = Author.objects.create(name='Paul')
ringo = Author.objects.create(name='Ringo')
 
entry.authors.add(john, paul, ringo)

 

 

3. Delete 문

 

b.delete()
# (1, {'Entry Go': 1})

참고 : https://eunjin3786.tistory.com/337