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 django

django.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)。

参考：https://docs.djangoproject.com/en/3.1/topics/settings/#envvar-DJANGO_SETTINGS_MODULE

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),

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

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.

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。