1.前言：

將測試資料全部敲入資料庫非常繁瑣，而且如果與合作伙伴一起開發，部署，那麼他們肯定也不想把時間花在一個一個錄入資料的繁瑣過程中，這時候，建立一個批量錄入資料的指令碼（population script)就非常有必要。

2.程式碼：

假設在models.py中定義的資料為下面：

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（僅供參考）：

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.程式碼要點

（1）在獨立執行django的程式碼時，而不是通過 python manage.py runserver的方式執行時，必須使用django.setup()來引入Django專案的設定，而在引入設定之前還要指明 環境變數DJANGO_SETTINGS_MODULE用的是本專案的settings。

設定環境變數在python中常用os.environ，它返回一個字典型別，裡面包含了所有環境變數的鍵值對，所以在這裡使用字典的內建方法setdefault，將環境變數

'DJANGO_SETTINGS_MODULE' 設定為'tango_with_django_project.settings'（本專案的settings.py）。<br>參考：<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：（官方文件定義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>

　在這裡，需要注意的是，如果在建立model instance時，僅在model有預設值的情況下可以不輸入任何kwargs，否則必須至少輸入一個值（field,如這裡page的category，或者Category的name)，然後該方法會帶著這個值先去找有沒有該值下的model instance，如果沒有則建立一個新的，返回（object,created)，這裡object 是新建立的物件的reference，created為True.

4.執行檢視

執行python populate.py：

然後登陸admin頁面檢視：

可以看到，資料全部被讀入資料庫。

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