Python学习笔记之Django创建第一个数据库模型的方法

python manage.py migrate

from django.db import models
classQuestion(models.Model):
question_text = models.CharField(max_length=200)
pub_date = models.DateTimeField('date published')
classChoice(models.Model):
question = models.ForeignKey(Question, on_delete=models.CASCADE)
choice_text = models.CharField(max_length=200)
votes = models.IntegerField(default=0)

INSTALLED_APPS =[
'demo.apps.DemoConfig',
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
]

python manage.py makemigrations demo

python manage.py sqlmigrate demo 0001

python manage.py migrate

python manage.py shell

from demo.models importQuestion,Choice

Question.objects.all()

from django.utils import timezone
q =Question(question_text="What's new?", pub_date=timezone.now())
q.save()
q.id
q.question_text
q.pub_date
q.question_text = "What's up?"
q.save()
Question.objects.all()

from django.db import models
from django.utils.encoding import python_2_unicode_compatible
@python_2_unicode_compatible# only if you need to support Python 2
classQuestion(models.Model):
# ...
def __str__(self):
return self.question_text
@python_2_unicode_compatible# only if you need to support Python 2
classChoice(models.Model):
# ...
def __str__(self):
return self.choice_text
import datetime
from django.db import models
from django.utils import timezone
classQuestion(models.Model):
# ...
def was_published_recently(self):
return self.pub_date >= timezone.now()- datetime.timedelta(days=1)

from polls.models importQuestion,Choice
Question.objects.all()
Question.objects.filter(id=1)
Question.objects.filter(question_text__startswith='What')
from django.utils import timezone
current_year = timezone.now().year
Question.objects.get(pub_date__year=current_year)
Question.objects.get(id=2)
Question.objects.get(pk=1)
q =Question.objects.get(pk=1)
q.was_published_recently()
q =Question.objects.get(pk=1)
q.choice_set.all()
q.choice_set.create(choice_text='Not much', votes=0)
q.choice_set.create(choice_text='The sky', votes=0)
c = q.choice_set.create(choice_text='Just hacking again', votes=0)
c.question
q.choice_set.all()
q.choice_set.count()
Choice.objects.filter(question__pub_date__year=current_year)
c = q.choice_set.filter(choice_text__startswith='Just hacking')
c.delete()

python manage.py createsuperuser
Username: admin
Email address: admin@example.com
Password:**********
Password(again):*********
Superuser created successfully.

python manage.py runserver 8081

from django.contrib import admin
from.models importQuestion
admin.site.register(Question)