Overriding Django Model behaviour with Proxy Model
The main Usage of a proxy model is to override the main functionality of existing Model. It is a type of model inheritance without creating a new table in Database. It always query on original model with overridden methods or managers.
You can query, delete, edit, create etc on Proxy model but the effects will be on the original model.
You can define models as a proxy just by adding proxy = True in Meta class of model.
# Original Model
class Employee(models.Model):
EmployeeType = (
("D", "Developer"),
("M", "Manager"),
)
name = models.CharField(max_length=55)
type = models.CharField(choices=EmployeeType, max_length=1, default='D')
def __str__(self):
return self.name
# Model manager to use in Proxy model
class ManagerEmpManager(models.Manager):
def get_queryset(self):
return super(ManagerEmpManager, self).get_queryset().filter(
type='M')
def create(self, **kwargs):
kwargs.update({'type': 'M'})
return super(ManagerEmpManager, self).create(**kwargs)
# Proxy Model
class ManagerEmployee(Employee):
objects = ManagerEmpManager()
class Meta:
proxy = True
In ManagerEmployee I have overridden create method to set type as M(or Manager). whenever you create an object for ManagerEmployee model the type will be set to 'M' and a new object will be created for Employee table. Whenever you query on ManagerEmpManager you will get all employees who are Managers(or type field as 'M').
In [1]: from AppName.models import Employee, ManagerEmployee
In [2]: e1 = Employee.objects.create(name="Monkey")
In [3]: e1
Out[3]: <Employee: Monkey> # Employee object created with type 'D'
In [4]: e1.type
Out[4]: u'D'
In [2]: e2 = ManagerEmployee.objects.create(name="Cow")
In [6]: e2
Out[6]: <ManagerEmployee: Cow> # object created with type 'M' for model ManagerEmployee(original model Employee)
In [3]: e2.type
Out[3]: u'M'
In [4]: ManagerEmployee.objects.all() # To get all ManagerEmployee objects(or type 'M') as we defined in ManagerEmpManager class.
Out[4]: <QuerySet [<ManagerEmployee: Cow>]>
In [5]: Employee.objects.all()
Out[5]: <QuerySet [<Employee: Monkey>, <Employee: Cow>]>
Register ManagerEmployee model in admin.py file to get a separate interface for ManagersEmployee model.
How to maintain user session across sub domains in Django
Nowadays, people are using wildcard domains to provide same user experience across different domains. Using subdomains, we can be able to host multiple sites with …
Implementation of single sign on using auth0 in django application
As the no of applications increases, users need to create username & passwords, need to remember for each application. Users can't remember these details and, …
How to implement TokenBasedAuthentication in DjangoRestFramework?
This blog explains you how to use Token Authentication to authenticate users within a Django Application. Token Authentication is a way to authorize users by …
Understanding middleware functionality in django2.0
Understanding new style of middleware in Django2.0, the difference between old-style & new-style. How to write custom middlewares in new-style and upgrading from old-style middleware.
how to pass extra context data to serializers in django-rest-framework ?
Django rest-framework passes extra context data to serializers for the best design of rest applications. we can use "context" parameter in serializers to pass extra …
By using routers in django-rest-framework we can avoid writing of url patterns for different views. Routers will save a lot of time for developing the …
What's great about Django girls to inspire women into programming
Django girls is a non-profit organization, that helps women to learn Django programming language and to inspire them into programming. They are organizing workshops all …
Custom validations for serializer fields Django Rest Framework
we can write custom validations for serializer fields in Django Rest Framework. Validators are used to validate the data whether it is semantically valid or …
Django Custom Managers - A Manager is the interface through which database query operations are provided to Django models. At least one Manager exists for …
Introduction to API development using Django REST framework with Example
Introduction to API development with Django REST framework. You can build the API for any Django application. Pre-requisites are Django and OOPS(object oriented programming concepts) …
Django-REST Framework Object Level Permissions and User Level Permissions
Django-REST User Level Permissions and Object Level Permissions. User Level Permissions and Object level Permissions allow to serve customers based on their access levels or …
Heroku is a platform as a service (PaaS) that enables developers to build and run applications entirely in the cloud. 1. installation 2. Creating and Deploying app. 3. …
Reduce database queries in django with Conditional Expressions. By using Conditional Expressions we can use "If...Elif...Else" expressions while querying the database so that we can …
Querying with Django Q objects: Q object encapsulates a SQL expression in a Python object that can be used in database-related operations. Using Q objects …
How to Create initial django migrations for existing DB schema.
Django provides the comfort database migrations from its version 1.8, with which we can avoid the usage of third party packages like south. Adding migrations …
Using Github integration, we can get the user verified email id, general information, git hub URL, id, disk usage, public, private repo's, gists and followers, …
By writing unit test cases, you can evaluate each code component in the initial stage itself and it'll improve your app/code performance. Which is the …
Django - migrating from function based views to class based views
The single most significant advantage in Django class-based views is inheritance. On a large project it's likely that we will have lots of similar views. …
This blog describes about how to work with django-plugins. Django Plugin is a Simple Plugin Framework for Django. By using django-plugins, you can make your …
We use sorl-thumbnail for scaling images by keeping the original one intact. Sorl proven to be great tool for generating different sized images throughout website. …
Extract text with OCR for all image types in python using pytesseract
Optical Character Recognition(OCR) is the process of electronically extracting text from images or any documents like PDF and reusing it in a variety of ways …
Factory Boy is a fixtures replacement tool. It allows you to use objects customized for the current test, while only declaring the test-specific fields. For …
Payment Gateways which facilitate communication within banks and Security is an integral component of all payment gateways, as sensitive data such as Credit Card Numbers …
Django Template Tags are simple Python functions that accept a value, an optional argument, and return a value to be displayed on the page. First, In …
Python Memcached Implementation for Django project
Memcache is a memory caching system that helps web applications and mobile app backends to improve performance and scalability. We should consider using Memcache when …
This package uses double-entry bookkeeping where every transaction is recorded twice (once for the source and once for the destination). This ensures the books always …
How to customize the admin actions in list pages of Django admin?
Django by default provides automatic admin interface, that reads metadata from your models to provide a beautiful model interface where trusted users can manage content …
404 Page not found and 500 Internal server errors generally occur in every website. When these errors occurs, generally for Django application it will load …
Autocomplete with Django-Haystack and Elasticsearch with single letter querying.
Django's haystack provides autocomplete functionality. To do autocomplete effectively, the search backend(elasticsearch in this case) uses n-grams (essentially a small window passed over the string). …
Celery provides asynchronous job queues, which allows you to run Python functions in the background. Celery is on the Python Package Index (PyPi), and can …
Implement search with Django-haystack and Elasticsearch Part-1
Haystack works as search plugin for django. You can use different back ends Elastic-search, Whose, Sorl, Xapian to search objects. All backends work with same …
Django comes with a simple permissions system. It provides a way to assign permissions to specific users and groups of users. We can have permissions …
Django’s template system comes with a wide variety of built-in tags and filters designed to address the presentation logic needs of your application. You can …
E-commerce is integration is becoming almost essential for every web application now a days. There are so many payment gateways to integrate with our application. …
We always struggle to give users customization's even before they login to the system like abc.micropyramid.com and django don't know how to handle that out …
In some cases the we might want to store generic model object, rather a particular specific model as 'ForeignKey'. Generic model object means adding a …
Understanding Django model formsets in detail and their advanced usage.
Silmilar to the regular formsets, django also provide model formset that make it easy to work with django models. Django model formsets provide a way …
Using Facebook integration, we can get the user verified email id, general information, friends, pages, groups and you can post on his profile, facebook pages, …
Django template engine comes as part of django framework and its very easy, extensible and handy to develop complex web applications with simplest efforts. Lets …
Django model is the single, definitive source of data about your data. It contains the essential fields and behaviors of the data you’re storing. Generally, …
Add captcha to django web page using Python-reCaptcha
Python-reCaptcha is a pythonic and well-documented reCAPTCHA client that supports all the features of the remote API to generate and verify CAPTCHA challenges. To add …
Django forms is powerful module to help django application development in rendering html from model, validate input from http request to model specifications. And we …
Django is a high-level, free and open-source Python Web framework that encourages rapid development. Django follows the model–view–controller (MVC) architectural pattern. Django's primary goal is …
Subscribe and Stay Updated about our Webinars, news and articles on Django, Python, Machine Learning, Amazon Web Services, DevOps, Salesforce, ReactJS, AngularJS, React Native.
* We don't provide your email contact details to any third parties
Download Django CRM
An open source CRM developed by Micropyramid Get Code Here