No.6 创建模型

from django.db import models


class Question(models.Model):
    question_text = models.CharField(max_length=200)
    pub_date = models.DateTimeField('date published')


class Choice(models.Model):
    question = models.ForeignKey(Question, on_delete=models.CASCADE)
    choice_text = models.CharField(max_length=200)
    votes = models.IntegerField(default=0)

python manage.py makemigrations polls

Migrations for 'polls':
  polls/migrations/0001_initial.py
    - Create model Question
    - Create model Choice

python manage.py sqlmigrate polls 0001

python manage.py migrate

python manage.py shell

>>> from polls.models import Choice, Question

# 查询Question的所有数据
>>> Question.objects.all()
<QuerySet []>

>>> from django.utils import timezone
# 插入一条数据
# 创建一条数据的Question实例
>>> q = Question(question_text="你知道猿变实验室吗？", pub_date=timezone.now())
# 使用save方法完成数据的插入
>>> q.save()

# 通过属性id，可以获得插入数据的id
>>> q.id
1

# 数据的每个字段都是实例的属性
>>> q.question_text
"你知道猿变实验室吗？"

>>> q.pub_date
datetime.datetime(2012, 2, 26, 13, 0, 0, 775217, tzinfo=<UTC>)

# 通过更改属性值，可以达到修改字段值的目的
>>> q.question_text = "你知道猿变吗？"
>>> q.save()

# 再执行一次，就会有数据了，成功
>>> Question.objects.all()

>>> q.choice_set.create(choice_text="是的")

>>> q.choice_set.all()
<QuerySet [<Choice: Choice object (1)>, <Choice: Choice object (2)>]>

>>> choice_obj = Choice.objects.first()
>>> choice_obj.question
<Question: Question object (3)>