Django如何批量创建Model

1.前言：

将测试数据全部敲入数据库非常繁琐，而且如果与合作伙伴一起开发，部署，那么他们肯定也不想把时间花在一个一个录入数据的繁琐过程中，这时候，创建一个批量录入数据的脚本（population script)就非常有必要。

2.代码：

假设在models.py中定义的数据为下面：

from django.db import models # Create your models here.class Category(models.Model): name=models.CharField(max_length=128,unique=True) class Meta: verbose_name_plural='Categories' def __str__(self): return self.name class Page(models.Model): category=models.ForeignKey(Category,on_delete=models.CASCADE) title=models.CharField(max_length=128) url=models.URLField() views=models.IntegerField(default=0) def __str__(self): return self.title

populate.py如下（仅供参考）：

import os# In your live server environment, you’ll need to tell your WSGI application what settings# file to use. Do that with os.environ:#reference source:https://docs.djangoproject.com/en/3.1/topics/settings/os.environ.setdefault(’DJANGO_SETTINGS_MODULE’,’tango_with_django_project.settings’) import djangodjango.setup()from rango.models import Category,Page#If you’re using components of Django “standalone” ? for example, writing a Python script# which loads some Django templates and renders them, or uses the ORM to fetch some data ?# there’s one more step you’ll need in addition to configuring settings.# After you’ve either set DJANGO_SETTINGS_MODULE or called configure(), you’ll need to call# django.setup() to load your settings and populate Django’s application registry.# reference source:https://docs.djangoproject.com/en/3.1/topics/settings/def populate(): python_pages=[ {'title':'official', 'url':'http://docs.python.org'}, {'title':'How to think like a computer scientis', 'url':'http://ww.greenteapress.com/thinkpy'}, {'title':'learn python in 10 minites', 'url':'http://www.korokithakis.net/tutorials/python'} ] django_pages=[ {'title':'Official Django tutorial', 'url':'https://docs.jangoproject.com/en/1.9/intro'}, {'title':'Django Rocks', 'url':'http://www.djangorocks.com' }, {'title':'HOw to tango with django', 'url':'http://www.tangowithdjango.com'} ] other_pages=[ {'title':'Bottle', 'url':'http://bottlepy.org'}, {'title':'Flask', 'url':'http://flask.pocoo.org'}, {'title':'Bold test', 'url':'http://boldtest.org'} ] cats={'Python':{'pages':python_pages}, 'Django':{'pages':django_pages}, 'Other Frameworks':{'pages':other_pages}} def add_page(cat,title,url,views=0): p=Page.objects.get_or_create(category=cat,title=title,url=url,views=views)[0] # p.url=url # p.views=views p.save() return p def add_cat(name): c=Category.objects.get_or_create(name=name)[0] c.save() return c for cat,cat_data in cats.items(): c=add_cat(cat) for p in cat_data[’pages’]: add_page(c,p['title'],p[’url’]) for c in Category.objects.all(): for p in Page.objects.filter(category=c): print('-{0}-{1}'.format(str(c),str(p))) if __name__=='__main__': print('starting rango population script') populate()

　3.代码要点

（1）在独立运行django的代码时，而不是通过 python manage.py runserver的方式运行时，必须使用django.setup()来引入Django项目的设置，而在引入设置之前还要指明 环境变量DJANGO_SETTINGS_MODULE用的是本项目的settings。

设置环境变量在python中常用os.environ，它返回一个字典类型，里面包含了所有环境变量的键值对，所以在这里使用字典的内置方法setdefault，将环境变量

’DJANGO_SETTINGS_MODULE’ 设置为’tango_with_django_project.settings’（本项目的settings.py）。<br>参考：<a href='https://docs.djangoproject.com/en/3.1/topics/settings/#envvar-DJANGO_SETTINGS_MODULE' rel='external nofollow' >https://docs.djangoproject.com/en/3.1/topics/settings/#envvar-DJANGO_SETTINGS_MODULE</a>

（2）get_or_create方法：（官方文档定义https://docs.djangoproject.com/en/3.1/ref/models/querysets/#get-or-create如下）

get_or_create(defaults=None, **kwargs)A convenience method for looking up an object with the given kwargs (may be empty if your model has defaults for all fields),<br> creating one if necessary.Returns a tuple of (object, created), where object is the retrieved or created object and created is a boolean specifying whether a new <br>object was created.This is meant to prevent duplicate objects from being created when requests are made in parallel, and as a shortcut to boilerplatish code. <br>

　在这里，需要注意的是，如果在创建model instance时，仅在model有默认值的情况下可以不输入任何kwargs，否则必须至少输入一个值（field,如这里page的category，或者Category的name)，然后该方法会带着这个值先去找有没有该值下的model instance，如果没有则创建一个新的，返回（object,created)，这里object 是新创建的对象的reference，created为True.

4.运行查看

运行python populate.py：

然后登陆admin页面查看：

可以看到，数据全部被读入数据库。

以上就是Django如何批量创建Model的详细内容，更多关于Django批量创建Model的资料请关注好吧啦网其它相关文章！