text: from django.db import models
  
  class Category(models.Model):
      name = models.CharField('category', max_length=255)
      
      # 表示した時に
      # Category object
      # のようになるのを防ぐため、__str__を定義
      def __str__(self):
          return self.name
  
  
  class Article(models.Model):
      title = models.CharField('title', max_length=255)
      categories = models.ManyToManyField(Category)
      content = models.TextField('content')
      
  