Django如何批量創建Model
1.前言:
將測試數據全部敲入數據庫非常繁瑣,而且如果與合作伙伴一起開發,部署,那么他們肯定也不想把時間花在一個一個錄入數據的繁瑣過程中,這時候,創建一個批量錄入數據的腳本(population script)就非常有必要。
2.代碼:
假設在models.py中定義的數據為下面:
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 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.代碼要點
(1)在獨立運行django的代碼時,而不是通過 python manage.py runserver的方式運行時,必須使用django.setup()來引入Django項目的設置,而在引入設置之前還要指明 環境變量DJANGO_SETTINGS_MODULE用的是本項目的settings。
設置環境變量在python中常用os.environ,它返回一個字典類型,里面包含了所有環境變量的鍵值對,所以在這里使用字典的內置方法setdefault,將環境變量
’DJANGO_SETTINGS_MODULE’ 設置為’tango_with_django_project.settings’(本項目的settings.py)。<br>參考:<a rel='external nofollow' >https://docs.djangoproject.com/en/3.1/topics/settings/#envvar-DJANGO_SETTINGS_MODULE</a>
(2)get_or_create方法:(官方文檔定義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>
在這里,需要注意的是,如果在創建model instance時,僅在model有默認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,如這里page的category,或者Category的name),然后該方法會帶著這個值先去找有沒有該值下的model instance,如果沒有則創建一個新的,返回(object,created),這里object 是新創建的對象的reference,created為True.
4.運行查看
運行python populate.py:
然后登陸admin頁面查看:
可以看到,數據全部被讀入數據庫。
以上就是Django如何批量創建Model的詳細內容,更多關于Django批量創建Model的資料請關注好吧啦網其它相關文章!
相關文章:
