django_4数据库2——表外键

from django.db import models

# Create your models here.
class Enter(models):
    name = models.CharField(max_length=30)
    
    def __str__(self):
        return self.name
        
    __repr__ = __str__
    
class Blog(models):
    name = models.CharField(max_length=30)
    entry = models.ForeignKey(Enter)　　　　　　#参数为one项的类名
    
    def __str__(self):
        return self.name
        
    __repr__ = __str__   

In [1]: from blog.models import Entry, Blog

In [2]: entry1 = Entry.objects.create(name=‘alen‘)　　　　　　　　　　　　#创建对应的one项（Entry）

In [3]: entry2 = Entry.objects.create(name=‘max‘)

In [4]: entry3 = Entry.objects.create(name=‘carl‘)

In [6]: blog1 = Blog.objects.create(name=‘alen_blog1‘, entry=entry1)　　#创建对应many项

In [8]: blog1.entry　　　　　　　　　　#(many)从many端进行检索到one
Out[8]: alen

In [9]: blog1.entry_id
Out[9]: 1

In [10]: entry1.blog_set　　　　　　　　#（one）它所对应的blog（many）都有哪些
Out[10]: <django.db.models.fields.related_descriptors.create_reverse_many_to_one_manager.<locals>.RelatedManager at 0x7f438ce2db00>

In [11]: entry1.blog_set.all()
Out[11]: <QuerySet [alen_blog1]>