📍ManyToManyField

🌱models.py

from django.db import models

# Create your models here.
class Actor(models.Model):
    first_name = models.CharField(max_length=45)
    last_name = models.CharField(max_length=45)
    date_of_birth=models.DateField()
    movies=models.ManyToManyField('Movie')
    #관계명을 직접 지어주고싶으면 ('Movie',db_table="actors_movies")
    #클래스명소문자_set 가 아닌 새로운 이름지정원하면 ('Movie',db_table="actors_movies",related_name='movie')
    class Meta:
        db_table='actors'
    def __str__(self):
        return self.first_name + self.last_name
        #__str__ 함수:객체를 문자열로 표현한 것을 반환 ex.<Actor:이지은 >

class Movie(models.Model):
    title = models.CharField(max_length=45)
    release_date = models.DateField()
    running_time=models.IntegerField()
    
    
    class Meta:
        db_table='movies'
        
    def __str__(self):
        return self.title
        #__str__ 함수:객체를 문자열로 표현한 것을 반환 ex.<Movie: 브로커>

내가 만든 테이블은 actors와 movies 2개지만
ManyToManyField()을 사용하여 actors_movies 라는 테이블이 자동을 생성되었다.

actors_movies테이블은 id,actor_id,movie_id로 구성되어있다.

데이터 넣기

>>> from movies.models import Actor,Movie
>>> Movie.objects.create(title='브로커',release_date='2022-06-08',running_time=129)
<Movie: 브로커> 
>>> Movie.objects.create(title='기생충',release_date='2019-05-30',running_time=132)
<Movie: 기생충>
>>> Movie.objects.create(title='범죄도시2',release_date='2022-05-18',running_time=106)
<Movie: 범죄도시2>
>>> Movie.objects.create(title='부라더',release_date='2017-11-02',running_time=102)
<Movie: 부라더>
>>> Actor.objects.create(first_name='이',last_name='지은',date_of_birth='1993-05-16')
<Actor: 이지은>
>>> Actor.objects.create(first_name='마',last_name='동석',date_of_birth='1971-03-01')
<Actor: 마동석>
>>> Actor.objects.create(first_name='송',last_name='강호',date_of_birth='1967-02-25')
<Actor: 송강호>

ManyToManyField

첫번째 방법

>>> Actor.objects.get(id=1).movies.add(Movie.objects.get(id=1))
>>> Actor.objects.get(id=3).movies.add(Movie.objects.get(id=1))
>>> Actor.objects.get(id=3).movies.add(Movie.objects.get(id=2))
>>> Actor.objects.get(id=2).movies.add(Movie.objects.get(id=3))
>>> Actor.objects.get(id=2).movies.add(Movie.objects.get(id=4))

👉 actor_id=1에 연결될 영화목록에 movie_id=1 추가
👉 actor_id=3에 연결될 영화목록에 movie_id=1 추가
.
.
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두번째 방법

>>> a1 = Actor.objects.get(id=1)
>>> a1.save() #save해줘야함! 꼭!
>>> a2 = Actor.objects.get(id=2)
>>> a2.save()
>>> a3 = Actor.objects.get(id=3)
>>> a3.save()
>>> m1 = Movie.objects.get(id=1)
>>> m1.save()
>>> m2 = Movie.objects.get(id=2)
>>> m2.save()
>>> m3 = Movie.objects.get(id=3)
>>> m3.save()
>>> m4 = Movie.objects.get(id=4)
>>> m4.save() 
>>> a1.movie.add(m1)
>>> a2.movie.add(m3,m4)
>>> a3.movie.add(m1,m2)
#Actor클래스에 ManyToManyField()가 있으니 actor에 movie를 넣기