django中的积累

只要继承了model.Model, 就会生成一个新的表,但是,如果在Meta方法中添加abstract=True,就不会产生新的表,而是作为一个基类存放多个表共同拥有的方法和字段等

from django.db import models


class Commen(models.Model):
    create_time = models.DateTimeField(auto_now_add=True)
    update_time = models.DateTimeField(auto_now=True)
    class Meta:
        # 添加关键字,不会产生新的表
        abstract = True
# 这张表继承了Base,哪怕没有字段create_time和update_time,也同样会展示出来
class CourseType(Base):
    title = models.CharField('课程类别',max_length=16)
    sequence = models.IntegerField('展示顺序',default=10)

    class Meta:
        db_table = 'tb_coursetype'

    def __str__(self):
        return self.title

 

0.路径表关系梳理

 

 

1.路径表
# 路径表 

class Path(Base):
  title = models.CharField('路径名', max_length=16)
  img = models.ImageField('路径图片', upload_to='path', null=True)
  desc = models.CharField('路径描述', max_length=255)
  user = models.ManyToManyField('user.User', blank=True)
  

  def course_total(self):
    count = 0
    for jd in self.jieduan.all():
      count = count + jd.courses.count()
    return count

    class Meta:
      db_table = 'tb_path'
    

    def __str__(self):
      return self.title

 

2.阶段表
class JieDuan(Base): 
  title = models.CharField('阶段名', max_length=16) 
  serial_num = models.IntegerField('阶段序号')
  path = models.ForeignKey(Path, related_name='jieduan', on_delete=models.SET_NULL, null=True)
  courses = models.ManyToManyField(Course, blank=True)

  class Meta:
    db_table = 'tb_jieduan'

  def __str__(self):
    return "%s-第%s阶段-%s" % (self.path.title, self.serial_num, self.title)

 

 

 

 

 
posted @ 2020-10-13 21:50  就叫我老李吧  阅读(91)  评论(0编辑  收藏  举报