Book Image

Web Development with Django Cookbook

By : Aidas Bendoraitis
Book Image

Web Development with Django Cookbook

By: Aidas Bendoraitis

Overview of this book

<p>Django is easy to learn and solves all types of web development problems and questions, providing Python developers an easy solution to web-application development. With a wealth of third-party modules available, you'll be able to create a highly customizable web application with this powerful framework.</p> <p>Web Development with Django Cookbook will guide you through all web development processes with the Django framework. You will get started with the virtual environment and configuration of the project, and then you will learn how to define a database structure with reusable components. Find out how to tweak the administration to make the website editors happy. This book deals with some important third-party modules necessary for fully equipped web development.</p> <p>&nbsp;</p> <div class="book-toc-chapter">&nbsp;</div> <h2>Read an extract of the book</h2> <h3>Creating Filterable RSS Feeds</h3> <p>Django comes with a syndication feed framework that allows you to create RSS and Atom feeds easily. RSS and Atom feeds are XML documents with specific semantics. They can be subscribed in an RSS reader such as Feedly, or they can be aggregated into other websites, mobile applications, or desktop applications. In this recipe, we will create <em>BulletinFeed</em>, which provides a bulletin board with images. Moreover, the results will be filterable by URL query parameters.</p> <h4>Getting ready</h4> <p>Create a new <em>bulletin_board</em> app and put it under <em>INSTALLED_APPS</em> in the settings.</p> <h4>How to do it…</h4> <p>We will create a <em>Bulletin</em> model and an RSS feed for it that can be filtered by type or category, so that the visitor can subscribe only to bulletins that are, for example, offering used books:</p> <ol> <li>In the <em>models.py</em> file of that app, add the models <em>Category</em> and <em>Bulletin</em> with a foreign key relationship between them: <pre class="line-numbers"><code class="language-python">#bulletin_board/models.py # -*- coding: UTF-8 -*- from django.db import models from django.utils.translation import ugettext_lazy as _ from django.core.urlresolvers import reverse from utils.models import CreationModificationDateMixin from utils.models import UrlMixin TYPE_CHOICES = ( ("searching", _("Searching")), ("offering", _("Offering")), ) class Category(models.Model): title = models.CharField(_("Title"), max_length=200) def __unicode__(self): return self.title class Meta: verbose_name = _("Category") verbose_name_plural = _("Categories") class Bulletin(CreationModificationDateMixin, UrlMixin): bulletin_type = models.CharField(_("Type"), max_length=20, choices=TYPE_CHOICES) category = models.ForeignKey(Category, verbose_name=_("Category")) title = models.CharField(_("Title"), max_length=255) description = models.TextField(_("Description"), max_length=300) contact_person = models.CharField(_("Contact person"), max_length=255) phone = models.CharField(_("Phone"), max_length=200, blank=True) email = models.CharField(_("Email"), max_length=254, blank=True) image = models.ImageField(_("Image"), max_length=255, upload_to="bulletin_board/", blank=True) class Meta: verbose_name = _("Bulletin") verbose_name_plural = _("Bulletins") ordering = ("-created",) def __unicode__(self): return self.title def get_url_path(self): return reverse("bulletin_detail", kwargs={"pk": self.pk}) </code></pre> </li> <li>Then, create <em>BulletinFilterForm</em> that allows the visitor to filter bulletins by type and by category, as follows: <pre class="line-numbers"><code class="language-python">#bulletin_board/forms.py # -*- coding: UTF-8 -*- from django import forms from django.utils.translation import ugettext_lazy as _ from models import Category, TYPE_CHOICES class BulletinFilterForm(forms.Form): bulletin_type = forms.ChoiceField( label=_("Bulletin Type"), required=False, choices=(("", "---------"),) + TYPE_CHOICES, ) category = forms.ModelChoiceField( label=_("Category"), required=False, queryset=Category.objects.all(), ) </code></pre> </li> <li>Add a <em>feeds.py</em> file with the <em>BulletinFeed</em> class inside, as follows: <pre class="line-numbers"><code class="language-python">#bulletin_board/feeds.py # -*- coding: UTF-8 -*- from django.contrib.syndication.views import Feed from django.core.urlresolvers import reverse from models import Bulletin, TYPE_CHOICES from forms import BulletinFilterForm class BulletinFeed(Feed): description_template = "bulletin_board/feeds/bulletin_description.html" def get_object(self, request, *args, **kwargs): form = BulletinFilterForm(data=request.REQUEST) obj = {} if form.is_valid(): obj = { "bulletin_type": form.cleaned_data["bulletin_type"], "category": form.cleaned_data["category"], "query_string": request.META["QUERY_STRING"], } return obj def title(self, obj): t = u"My Website - Bulletin Board" # add type "Searching" or "Offering" if obj.get("bulletin_type", False): tp = obj["bulletin_type"] t += u" - %s" % dict(TYPE_CHOICES)[tp] # add category if obj.get("category", False): t += u" - %s" % obj["category"].title return t def link(self, obj): if obj.get("query_string", False): return reverse("bulletin_list") + "?" + obj["query_string"] return reverse("bulletin_list") def feed_url(self, obj): if obj.get("query_string", False): return reverse("bulletin_rss") + "?" + obj["query_string"] return reverse("bulletin_rss") def item_pubdate(self, item): return item.created def items(self, obj): qs = Bulletin.objects.order_by("-created") if obj.get("bulletin_type", False): qs = qs.filter( bulletin_type=obj["bulletin_type"], ).distinct() if obj.get("category", False): qs = qs.filter( category=obj["category"], ).distinct() return qs[:30] </code></pre> </li> <li>Create a template for the bulletin description in the feed as follows: <pre class="line-numbers"><code class="language-python">{#templates/bulletin_board/feeds/bulletin_description.html#} {% if obj.image %} &lt;p&gt;&lt;a href="{{ obj.get_url }}"&gt;&lt;img src="http://{{ request.META.HTTP_HOST }}{{ obj.image.url }}" alt="" /&gt;&lt;/a&gt;&lt;/p&gt; {% endif %} &lt;p&gt;{{ obj.description }}&lt;/p&gt; </code></pre> </li> <li>Create a URL configuration for the <em>bulletin board</em> app and include it in the root URL configuration, as follows: <pre class="line-numbers"><code class="language-python">#templates/bulletin_board/urls.py # -*- coding: UTF-8 -*- from django.conf.urls import * from feeds import BulletinFeed urlpatterns = patterns("bulletin_board.views", url(r"^$", "bulletin_list", name="bulletin_list"), url(r"^(?P&lt;bulletin_id&gt;[0-9]+)/$", "bulletin_detail", name="bulletin_detail"), url(r"^rss/$", BulletinFeed(), name="bulletin_rss"), ) </code></pre> </li> <li>You will also need the views and templates for the filterable list and details of the bulletins. In the <em>Bulletin</em> list page template, add this link: <pre class="line-numbers"><code class="language-python">&lt;a href="{% url "bulletin_rss" %}?{{ request.META.QUERY_STRING }}"&gt;RSS Feed&lt;/a&gt;</code></pre> </li> </ol> <h4>How it works…</h4> <p>So, if you have some data in the database and you open <em>http://127.0.0.1:8000/bulletin-board/rss/?bulletin_type=offering&amp;category=4</em> in your browser, you will get an RSS feed of bulletins with the type Offering and category ID 4.</p> <p>The <em>BulletinFeed</em> class has the <em>get_objects</em> method that takes the current <em>HttpRequest</em> and defines the <em>obj</em> dictionary used in other methods of the same class.</p> <p>The <em>obj</em> dictionary contains the bulletin type, category, and current query string.</p> <p>The <em>title</em> method returns the title of the feed. It can either be generic or related to the selected bulletin type or category. The <em>link</em> method returns the link to the original bulletin list with the filtering done. The <em>feed_url</em> method returns the URL of the current feed. The items method does the filtering itself and returns a filtered <em>QuerySet</em> of bulletins. And finally, the <em>item_pubdate</em> method returns the creation date of the bulletin.</p> <p>To see all the available methods and properties of the <em>Feed</em> class that we are extending, refer to the following documentation: <a href="https://docs.djangoproject.com/en/1.10/ref/contrib/syndication/#feed-class-reference">https://docs.djangoproject.com/en/1.10/ref/contrib/syndication/#feed-class-reference</a></p> <p>The other parts of the code are kind of self-explanatory!</p>
Table of Contents (17 chapters)
Web Development with Django Cookbook
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Preface

The Django framework is relatively easy to learn and it solves many web-related questions such as project structure, database object-relational mapping, templating, form validation, sessions, authentication, security, cookies, internationalization, basic administration, creating interfaces to access data from scripts, and more. Django is based on the Python programming language, whose code is clear and easy to read. Django also has a lot of third-party modules that can be used in conjunction with your own apps. Django has an established and vibrant community where you can find source code, get help, and contribute.

Django Web Development Cookbook will guide you through all web development processes with the Django 1.6 framework. You will get started with the virtual environment and configuration of the project and then you will learn how to define a database structure with reusable components. After this, you will move on to exploring the forms and views used to enter and list data. Then, you will continue with responsive templates and JavaScript to create the best user experience. After that, you will find out how to tweak the administration to make the website editors happy. You will also learn how to integrate your own functionality into Django CMS. The next step will be learning how to use hierarchical structures. Then, you will find out that collecting data from different sources and providing data to others in different formats isn't as difficult as you thought. And finally, you'll be introduced to some programming and debugging tricks and will be shown how to deploy the project to a remote dedicated server.

In contrast to other Django books, this book will deal not only with the code of the framework itself, but also with some important third-party modules necessary for fully equipped web development. The book also gives examples of rich user interfaces using the Bootstrap frontend framework and the jQuery JavaScript library.

What this book covers

Chapter 1, Getting Started with Django 1.6, will guide you through the basic configuration that is necessary to start any Django project. It will cover topics such as the virtual environment, version control, and project settings.

Chapter 2, Database Structure, will teach you how to write reusable pieces of code to use in your models. When you create a new app, the first thing to do is to define your models. Also, you will be told how to manage database schema changes using South migrations.

Chapter 3, Forms and Views, will show you some patterns used to create the views and forms for your data.

Chapter 4, Templates and JavaScript, will show you practical examples of using templates and JavaScript together. We bring together templates and JavaScript because information is always presented to the user by rendered templates and in modern websites, JavaScript is a must for a richer user experience.

Chapter 5, Custom Template Filters and Tags, will show you how to create and use your own template filters and tags, as the default Django template system is quite extensive, and there are more things to add for different cases.

Chapter 6, Model Administration, will guide you through extending the default administration with your own functionality, as the Django framework comes with a handy prebuilt model administration.

Chapter 7, Django CMS, deals with the best practices of using Django CMS, which is the most popular open source content management system made with Django, and extending it for your needs.

Chapter 8, Hierarchical Structures, shows that whenever you need to create a tree-like structure in Django, the django-mptt module comes in handy. This chapter shows you how to use it and how to set administration for hierarchical structures.

Chapter 9, Data Import and Export, demonstrates to us that very often there are cases when we need to transfer data from and to different formats, and retrieve it from and provide it to different sources. This chapter deals with management commands for data import and also APIs for data export.

Chapter 10, Bells and Whistles, will show some additional snippets and tricks useful in web development, debugging, and deployment.

What you need for this book

To develop with Django 1.6, you will need Python 2.6 or 2.7, the Pillow library for image manipulation, the MySQL database and MySQLdb bindings or PostgreSQL, virtualenv to keep each project's Python modules separated, and Git or Subversion for version control.

All other specific requirements are mentioned in each recipe separately.

Who this book is for

If you have created websites with Django but you want to sharpen your knowledge and learn some good approaches for how to treat different aspects of web development, this book is for you. It is intended for intermediate and professional Django users who need to build projects that must be multilingual, functional on devices of different screen sizes, and which scale over time.

Conventions

In this book, you will find a number of styles of text that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning.

Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "In the models.py file of the guerrilla_patches app, add the following content."

A block of code is set as follows:

# -*- coding: UTF-8 -*-
from django.utils import text
from slugify import slugify_de as awesome_slugify
awesome_slugify.to_lower = True
text.slugify = awesome_slugify

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

class ExtendedChangeList(main.ChangeList):

    def get_translated_list(self, model, field_list):
        language = get_language()
        translated_list = []
        opts = model._meta

Any command-line input or output is written as follows:

(myproject_env)$ fab dev deploy

New terms and important words are shown in bold. Words that you see on the screen, in menus or dialog boxes for example, appear in the text like this: "Go to Webmin | System | Scheduled Cron Jobs | Create a new scheduled cron job and create a scheduled cron job with these properties."

Note

Warnings or important notes appear in a box like this.

Tip

Tips and tricks appear like this.

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