Django community: Community blog posts RSS
This page, updated regularly, aggregates Community blog posts from the Django community.
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Sure Fire Way Your Forms Don't Validate
I saw this question being asked few different times. “Why aren’t my forms validating?”. When you do everything correctly, it can be really annoying if your forms don’t validate. All of their code looked perfect. I couldn’t figure out why the forms weren’t validating correctly. Maybe it’s a bug in Django? No… I looked at the HTML of the form itself: <form action="{% url 'poll:submit' %}" method="POST"> {% csrf_token %} <div class="form-group"> <label for="comment">comment :</label> <textarea class="form-control" rows="3" id="comment"></textarea> </div> <button type="submit" class="btn btn-success">SUBMIT</button> </form> Can you spot the issue with this form? Before I get to the solution, this post requires a little bit more banter. I WANT to be able to solve this problem. I’ve been thinking about it for the last 2 - 3 weeks nonstop. If you do EVERYTHING correctly, but there seems that there’s NO solution, what do you do? How could you POSSIBLY figure out what is going wrong with your code? I’m a professional developers and sometimes, I make the same mistakes as above because it’s SO DAMN easy to make these COMPLETELY simple mistakes. But, what can you do about it? Here is a tiny bit of advice… Or, perhaps a heuristic ... -
Django Anti-Patterns: Signals
Django's Signal Dispatcher is a really powerful feature that you should never use. Ok, it has valid use cases, but they may be rarer than you think. First, to dispell a misconception about signals, they are not executed asynchronously. There is no background thread or worker to execute them. Like most of Django, they are fully "synchronous". I suspect this misconception stems from the event-driven coding pattern they use which is often seen in asynchronous languages/libraries. The event-driven pattern of signals looks neat at first, but often I see them mentioned as a source of frustration. It's not the author complaining, but the poor soul who inherits maintenance of the code and only learns of the existitance of signals when trying to track down unexpected behavior. Consider the following example using signals: # File: models.py from django.db import models class Pizza(models.Model): has_pepperoni = models.BooleanField(default=False) class ToppingSales(models.Model): name = models.CharField(max_length=100, unique=True) units_sold = models.PositiveIntegerField(default=0) # File: signals.py from django.db.models.signals import post_save from django.db.models import F from django.dispatch import receiver from .models import Pizza def pizza_saved_handler(sender, instance, created, **kwargs): if created and instance.has_pepperoni: ToppingSales.objects.filter(name='pepperoni').update( units_sold=F('units_sold') + 1) # File: app.py from django.apps import AppConfig from django.db.models.signals import post_save class PizzeriaConfig(AppConfig): def ready(self): ... -
Caktus at DjangoCon2017
In less than a month we’ll be heading out to Spokane, WA for DjangoCon 2017. We’re proud to be attending as sponsors for the eighth year, and look forward to greeting everyone at our booth. On August 16th, we’ll be raffling off a GoPro Session action camera, so be sure to stop by and enter. We’ll also have our comfy new t-shirts and some limited-edition Caktus 10th Anniversary water bottles to give away. They went fast at PyCon, so don’t wait to get yours. As part of our commitment to sharing quality Django content with the community, we’ll also be offering a survey at the booth to find out what you, our audience, are interested in seeing more of. We hope you’ll help us out! If you can’t make it to DjangoCon but still want to participate, you can take the survey on Ona. Speakers One of our very own developers will be speaking at DjangoCon this year! We’re excited that Charlotte Mays was selected to speak about writing APIs for almost anything, in which she’ll cover the power and flexibility of Django Rest Framework. Congratulations to Charlotte! We hope you’ll all go have a listen on Monday, August 14th ... -
What is SECRET_KEY in Django?
Do you ever want to know how the SECRET_KEY works? It’s sitting in your settings.py file but do you ever wonder why you need it? If you look at the documentation, you’ll discover some very interesting things about the SECRET_KEY setting. In the Cryptographic signing section of the Django docs, it says: You may also find signing useful for the following: Generating “recover my account” URLs for sending to users who have lost their password. Ensuring data stored in hidden form fields has not been tampered with. Generating one-time secret URLs for allowing temporary access to a protected resource, for example a downloadable file that a user has paid for. And I’m going to add one more thing to this list: Signing cookies so that you know that your users’ cookies are not being tampered by a hacker. How can you use the SECRET_KEY to determine if data has been tampered? The first thing you need to do is sign your data. from django.core.signing import Signer signer = Signer() value = signer.sign("My secret data") value Now, your signed data is saved in the value variable. How do you make sure that your data hasn’t been tampered with? from django.core import ... -
Building Web Apps with Django and Angular 2+ CLI
Angular CLI is a command line utility which enables you to quickly generate and build Angular 2+ apps .It takes care of much of the configuration and let you focus on implementing your next idea so it's a great tool for bootstraping modern JavaScript projects based on Angular 2+ . In this tutorial we are going to see how to serve and integrate an Angular 2+ web application (as a frontend ) with a Django backend . Communication between Django and Angular 2+ happens through a Restful API ,so for testing if our integration works, as expected ,you need to have a small testing API built in the Django backend . You can use any Rest API generator for Django such as Django Rest Framework (DRF) or Tastypie to build some API endpoints . I have previously created an API for a simple product manager app with Django and DRF so I'm going to use it in this tutorial to test the integration with the Angular 2+ frontend app . Requirements Before we can start building our demo app ,there are some requirements that we need to have installed on our system : Python , Virtualenv and PIP . Node.js ... -
Building Apps with Create React App and Django
Create React App is an npm tool to generate React apps without any build configurations for tools such as Webpack or Babel .That doesn't mean these tools are not used but they are just hidden so you can focus on building your React app instead of setting up build environments . By issuing a few commands you can generate a React app and start building your next idea in time record but if you need to integrate your app with a server framework such as Django in our case we still need to do little configuration so you can deploy your React app as a static front end for your Django project . In this How To tutorial we are going to see how to use Create React App with Django to create our Django app front end using React in both development and production environments . Lets start by generating a Django project from scratch : $ virtualenv env $ source env/bin/activate $ pip install django $ django-admin.py startproject django-react-demo $ cd django-react-demo Create some API endpoints with Django Rest Framework Since the communication between React and Django happens over an API we need to create some Django API ... -
Building Web Apps with Django ,Webpack and React
Throughout this tutorial we are going to learn how to use React JavaScript library and Webpack with Django to create modern web applications . Webpack is a module bundler and a build tool that bundles JavaScript and other assets for better consuming by web browsers . The aim of this tutorial is to show you the steps for using React with Webpack as the front end of your Django web applications . So lets get started ! Create a virtual environment Lets start by creating a virtual environment using virtualenv so open your terminal then run : virtualenv myenv Next activate the environment with : source myenv/bin/activate Next install Django using pip : pip install django Then create a django project : django-admin.py startproject django-react-demo To be able to install npm modules we need to create an npm module .This can be done by adding a package.json with some information to a folder which marks the folder as an npm module . Add package.json Generate a package.json inside your project root folder using : npm init npm will ask you for some information ,enter them and hit Enter . Now lets install the npm dependencies we need in our project ... -
Getting started with Django Rest Framework by Building a Simple Product Inventory Manager
Django offers developers many packages/frameworks to build web Rest APIs ,among them Django Rest Framework or DRF which is by far the most popular and powerful Rest API Framework . In this tutorial we will see how to use DRF to create a Rest API for a simple products inventory manager with 4 models . Getting started Lets start by following these steps : Create a virtual environement . Install both Django and Django Rest Framework . Create A Django project . Create a Django app . Add database models in inventory/models.py # -*- coding: utf-8 -*- from __future__ import unicode_literals from django.db import models class Product(models.Model): sku = models.CharField(max_length=13,help_text="Enter Product Stock Keeping Unit") barcode = models.CharField(max_length=13,help_text="Enter Product Barcode (ISBN, UPC ...)") title = models.CharField(max_length=200, help_text="Enter Product Title") description = models.TextField(help_text="Enter Product Description") unitCost = models.FloatField(help_text="Enter Product Unit Cost") unit = models.CharField(max_length=10,help_text="Enter Product Unit ") quantity = models.FloatField(help_text="Enter Product Quantity") minQuantity = models.FloatField(help_text="Enter Product Min Quantity") family = models.ForeignKey('Family') location = models.ForeignKey('Location') def get_absolute_url(self): """ Returns the url to access a particular instance of Product. """ return reverse('product-detail-view', args=[str(self.id)]) def __str__(self): return self.title class Family(models.Model): reference = models.CharField(max_length=13, help_text="Enter Family Reference") title = models.CharField(max_length=200, help_text="Enter Family Title") description = models.TextField(help_text="Enter ... -
How to Customize Django Admin Application
Django Admin interface or app is a powerful feature of Django framework as it allows you to automatically scaffold a full featured CRUD application for your database models saving you from reinventing the wheel when building admin interfaces or back offices for your projects .It can also be used for building quick prototypes . Most developers are not aware of the hidden power of Django admin so in this tutorial we are going to show you how we can extend it to customize its look and also its behavior with custom actions . The Admin site is enabled by default in each generated Django project . To create an admin site or back office you need to follow these predefined steps : First create your database models in models.py Next register your models with Django Admin in admin.py module . Customize the admin area with optional look or custom actions and views . Lets use the models from a simple product inventory manager where we have 4 models : Product ,Family , Location and Transaction . After creating a skeleton project with django-admin.py utility .You'll have Django admin already included and configured for you all you have to do is ... -
Two Scoops of Django 1.11 Is Printed!
After longer than we expected, the shiny new print copies of Two Scoops of Django 1.11 are finally ready. We've shipped all pre-orders, and many of you who ordered it in advance should have the book in your hands. We're delighted by how well it's been received, which is due only to the help and encouragement of our readers. Right now you can order the print version of Two Scoops of Django 1.11 at either: Two Scoops Press (for autographed copies directly from us), or Amazon (this link sends you to your regional Amazon store) If you purchase the book on Amazon, please leave an honest review. Simply put, Amazon reviews make or break a book, each one responsible for additional sales. It's our dream that if sales of Two Scoops of Django 1.11 are good enough, we'll be able to justify doing less consulting and instead, writing more technical books. -
How to Add Django Admin Custom List Actions
Django has an Admin package which can be used to scaffold a full CRUD application based on your registered models . This is very useful for prototyping or even for creating working applications . The Admin application is also extensible so you can very easily customize or extend the generated app to meet your preferences and requirements . Lists views in Django Admin are used to show a specific registered model data in tabular format with default bulk actions that can be applied to selected rows . In this tutorial we will see how to extend the Django Admin List views with custom actions . Adding Custom List Actions Actions in Admin app are just regular Python functions that have three parameters : A ModelAdmin An HttpRequest A QuerySet So to add a cutsom action you need to add an action function in admin.py module where you register your models . Lets take a simple real example . First create a Django project then create an app then in : In models.py module we add this Product model # -*- coding: utf-8 -*- from __future__ import unicode_literals from django.db import models class Product(models.Model): sku = models.CharField(max_length=13,help_text="Enter Product Stock Keeping Unit") ... -
Optimizing and Squashing Django Migrations
Django migrations allow you to change , evolve and upgrade your database schema while keeping any existing database data intact .They also allow you to use version control tools such as Git with databases . In this tutorial we are going to learn how to optimize database migrations by squashing or combining them . Starting with Django 1.7 ,migrations became part of Django itself so you don't need to install any third party apps such as South to work with database migrations . To use migrations you frequently work with two commands which are : python manage.py makemigrations Which generates migration files according to the change in your Django models . And python manage.py migrate Which actually migrates or upgrades the database schema . But there are also other Django commands that can be used in certain situations such as when you need to optimize your migrations . How to squach migrations in Django ? Django has a management command that allows you to squach or combine multiple migration files into a single optimized migration file . You can simply invoke this command using : python manage.py squachmigrations Now lets consider this senario : You have a Django app named ... -
Custom Password Less Authentication in Django
Authentication backends allow the ability to change what method checks your users credentials. An Example for the use of custom authentication backend: For web services, ie Facebook authentication, you don't have access to user data like a password. Without password(not like random string) we can't create a user in django. Facebook connect provides you details of the currently authenticated user. But to maintain the login_required decorator or to a user request.user you still need to have them logged in using Django. That's where the Authentication Backend comes in. from django.contrib.auth.backends import ModelBackend from peeldb.models import User class PasswordlessAuthBackend(ModelBackend): """Log in to Django without providing a password. """ def authenticate(self, username=None): try: return User.objects.get(username=username) except User.DoesNotExist: return None def get_user(self, user_id): try: return User.objects.get(pk=user_id) except User.DoesNotExist: return None In your settings.py add AUTHENTICATION_BACKENDS += ( # ... your other backends 'social.auth_backend.PasswordlessAuthBackend', # path to your custom authentication file # appname.filename.classname ) then to authenticate a registered user, we can override authenticate function without password in our views like user = authenticate(username={{user_email}}) login(request, user) -
Towards Channels 2.0
Outlining my plan for iterating on Channels' design, and what the future might hold for both Django and Python in general. It's been around three years since I came up with the current Channels design - that of pushing everything over a networked "channel layer" and strictly separating protocol handling and business logic - and while it's generally working well for people, I have this feeling it can be improved, and I've been thinking about how for the past few months. This was brought into sharp focus by recent discussion about writing more of a standard interface for asyncio in particular, but also by Tom Christie's recent work on the same subject, so I've written up where my current thinking is to both help people understand where I'm going and to be more transparent about how I think about problems like this. So, let's start by looking at the issues with the current Channels design: You're forced to run everything (and I mean everything) over a networked channel layer. There are good reasons for this - I'll cover them later - but it's a lot to force on people and arguably the biggest dent to smooth scaling of a Channels-based ... -
How to Organize Your Models
How many models do you have in your models.py file? If your app has 1 models.py file that has a ridiculous number of models (10 - 15) it’s time to break them apart. So, how do you organize your models so they are easy to find, and work with in the future? “Fat models” are a good thing, because it prevents your views from getting too bloated. Just look at the internals of the Django User models. Each of those models have various properties and methods just hanging off them. This is good for the developer because you can put all your calculations and business logic in the model inside a method and just call it normally. Easy peasy! But, what if you have a models.py file that is just WAY TOO BIG. I’m not just talking about the models themselves, I’m talking about the entire FILE. One way you can do this is by creating a new folder in your app. You should call this folder: models. Now, add a __init__.py file along with a file for grouping of models. For example, if I’m recreating that Django User Model file, I might do something like this: . ├── __init__.py ... -
Django 1.11+ django.contrib.auth Class Based Views - Part 2 - Password Change and Reset
Since we can log in and logout what about managing our password? Learn the power of using the builtin Generic Class Based Views now in django.contrib.auth. They are simple to use once you know about them.Watch Now... -
Domain Name for Django Development Server
Isn't it strange that browsing the web you usually access the websites by domain names, however, while developing a Django website, you usually access it through IP address? Wouldn't it be handy to navigate through your local website by domain name too? Let's have a look what possibilities there are to access the local development server by a domain name. Access via IP Address You probably know the following line by heart since the first day of developing with Django and can type it with closed eyes? (myenv)$ python manage.py runserver When you run a management command runserver, it starts a lightweight Django development server which by default listens to HTTP requests on your local machine's port 8000, whereas by default, HTTP websites are running on the 80 and HTTPS websites are running on 443. Enter http://127.0.0.1:8000 in a browser and you can click through your Django project. Note that this is a local address and it is not accessible from other devices in the network. Other people accessing the same address from their computers will see what is provided by web servers on their own machines, if any web server is running there at all. Each device in a ... -
Markdown Cheatsheet
A quick reference to using Mar... -
Ask Vitor #3: Mocking Emails
Phillip Ahereza asks: I’m writing unit tests for my django app and I was wondering if there are any packages for mocking email or if there is any way I could mock sending and receiving of emails. Answer Basically what Django does when you run your test suite is switch your EMAIL_BACKEND to django.core.mail.backends.locmem.EmailBackend, so to prevent your application from sending emails during the tests execution. While using this backend, all emails sent are stored in the outbox attribute of the django.core.mail module. Let’s see one example on how you can use it to test the email outputs and so on. urls.py from django.conf.urls import url from mysite.core import views urlpatterns = [ url(r'^send/$', views.send, name='send'), ] views.py from django.http import HttpResponse from django.core.mail import send_mail def send(request): email = request.GET.get('email') if email and '@' in email: body = 'This is a test message sent to {}.'.format(email) send_mail('Hello', body, 'noreply@mysite.com', [email, ]) return HttpResponse('<h1>Sent.</h1>') else: return HttpResponse('<h1>No email was sent.</h1>') This is a simple view that expects a querystring parameter named email with a valid email address. If the email value fulfill our view requirements, an email is sent to this address. If the email is invalid or no email ... -
AJAXify Django Forms
## **Guide is currently under ... -
Django Framework ve Güvenlik
Merhaba arkadaşlar bu yazımda Django Framework ve Güvenlik konusunu ele alacağız. Bildiğiniz üzre Django, python programlama dili ile yazılmış olan bir web uygulaması geliştirme çatısıdır. Biz geliştiricilere sağladığı esneklik, kolaylıklığı ve hızı eklediğimiz de bizim için önemli olan bir web uygulaması geliştirme çatısıdır. Geliştiriciler için tercih edilmesinin en büyük nedeni yapmış olduğumuz web uygulamalarını daha... Django Framework ve Güvenlik yazısı ilk önce Python Türkiye üzerinde ortaya çıktı. -
Django AbstractUser ile Genişletme
User Modelini Genişletme Merhabalar, OneToOneField ile user modelini genişlettik. Fakat AbstractUser kullanarak genişletmek daha akıllıca bir hareket olacaktır. Yeni bir proje başlatıyorsanız, varsayılan Kullanıcı Modeli sizin için yeterli olsa bile özel bir kullanıcı modeline bir şekilde ihtiyaç duyacaksınız. AbstractUser model, varsayılan kullanıcı modeliyle aynı şekilde davranıyor, ancak ihtiyaç ortaya çıkarsa kullanmanız yeterlidir. Model.py giriş yapalım. [crayon-595ebcd4d5558309387880/] User adında... Django AbstractUser ile Genişletme yazısı ilk önce Python Türkiye üzerinde ortaya çıktı. -
Django Code Review
We want to help solve problems... -
The Purpose of Business
Businesses exist to create val... -
The Purpose of Business
Businesses exist to create val...
