The Definitive Guide to Django

Transcription

1 The Definitive Guide to Django Web Development Done Right, Second Edition cession No. ok ID for signout Adrian Holovaty and Jacob Kaplan-Moss 882 Apresse

2 Contents at a Glance About the Author xxvii About the Technical Reviewer xxix Acknowledgments xxxi Preface xxxiii Introduction ~ xxxv PART 1 Getting Started CHAPTER 1 Introduction to Django CHAPTER 2 Getting Started CHAPTER 3 Views and URLconfs CHAPTER 4 Templates CHAPTER 5 Models CHAPTER 6 The Django Admin Site CHAPTER 7 Forms PART 2 Advanced Usage CHAPTER 8 Advanced Views and URLconfs CHAPTER 9 Advanced Templates CHAPTER 10 Advanced Models CHAPTER 11 Generic Views CHAPTER 12 Deploying Django PART 3 CHAPTER 13 CHAPTER 14 CHAPTER 15 CHAPTER 16 CHAPTER 17 CHAPTER 18 CHAPTER 19 CHAPTER20 PART 4 APPENDIX A APPENDIX B APPENDIX C APPENDIX D APPENDIX E APPENDIX F APPENDIX G INDEX iv

3 Contents About the Author xxvii About the Technical Reviewer xxix Acknowledgments xxxi Preface xxxiii Introduction xxxv PART 1 Getting Started CHAPTER 1 Introduction to Django What Is a Web Framework? The MVC Design Pattern Django's History How to Read This Book Required Programming Knowledge Required Python Knowledge Required Django Version Getting Help What's Next? CHAPTER 2 Getting Started Installing Python Python Versions Installation Installing Django Installing an Official Release Installing the Trunk Version Testing the Django Installation vii

4 viii CONTENTS Setting Up a Database Using Django with PostgreSQL Using Django with SQLite Using Django with MySQL Using Django with Oracle Using Django Without a Database Starting a Project Running the Development Server What's Next? CHAPTER 5 CHAPTER 3 Views and URLconfs Your First Django-Powered Page: Hello World Your First View Your First URLconf A Quick Note About 404 Errors A Quick Note About the Site Root How Django Processes a Request Your Second View: Dynamic Content URLconfs and Loose Coupling Your Third View: Dynamic URLs Django's Pretty Error Pages What's Next? CHAPTER 4 Templates Template-System Basics Using the Template System Creating Template Objects Rendering a Template Multiple Contexts, Same Template Context Variable Lookup Playing with Context Objects Basic Template Tags and Filters Tags Filters _ Philosophies and Limitations Using Templates in Views CHAPTER 6

5 CONTENTS ix ' '' ' ' ' CHAPTER 5 CHAPTER 6 Template Loading render_to_response() The locals() Trick Subdirectories in get_ template() The include Template Tag Template Inheritance What's Next? Models The "Dumb" Way to Do Database Queries in Views The MTV (or MVC) Development Pattern Configuring the Database Your First App Defining Models in Python Your First Model Installing the Model Basic Data Access Adding Model String Representations Inserting and Updating Data Selecting Objects Filtering Data Retrieving Single Objects Ordering Data Chaining Lookups Slicing Data Updating Multiple Objects in One Statement Deleting Objects What's Next? The Django Admin Site The django.contrib Packages Activating the Admin Interface Using the Admin Site Adding Your Models to the Admin Site How the Admin Site Works Making Fields Optional Making Date and Numeric Fields Optional Customizing Field Labels

6 x CONTENTS Custom ModeiAdmin Classes Customizing Change Lists Customizing Edit Forms Users, Groups, and Permissions When and Why to Use the Admin Interface-And When NotTo What's Next? CHAPTER 7 Forms Getting Data from the Request Object Information About the URL Other Information About the Request CHAPTER 9 Information About Submitted Data A Simple Form-Handling Example Improving Our Simple Form-Handling Example Simple Validation Making a Contact Form Your First Form Class Tying Form Objects into Views Changing How Fields Are Rendered Setting a Maximum Length Setting Initial Values Adding Custom Validation Rules Specifying Labels Customizing Form Design What's Next? PART 2 Advanced Usage CHAPTER 8 Advanced Views and URLconfs URLconfTricks Streamlining Function Imports Using Multiple View Prefixes Special-Casing URLs in Debug Mode Using Named Groups Understanding the Matching/Grouping Algorithm Passing Extra Options to View Functions Using Default View Arguments

7 CONTENTS xi '' '''.' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' 116 n NotT o '.' ' ' ' ' '.'.. ' ' '... ' ' ' ' ' ' '''... ' ' '' ' 155 CHAPTER 9 Special-Casing Views Capturing Text in URLs Determining What the URLconf Searches Against Higher-Level Abstractions of View Functions Wrapping View Functions Including Other URLconts How Captured Parameters Work with includeo How Extra URLcont Options Work with includeo What's Next? Advanced Templat~s Template Language Review RequestContext and Context Processors django.core.context_processors.auth django.core.context_processors.debug django.core.context_processors.i18n django.core.context_processors.request Guidelines tor Writing Your Own Context Processors Automatic HTML Escaping How to Turn It Ott Notes Automatic Escaping of String Literals in Filter Arguments Inside Template Loading Extending the Template System Creating a Template Library Writing Custom Template Filters Writing Custom Template Tags Writing the Compilation Function Writing the Template Node Registering the Tag Setting a Variable in the Context Parsing Until Another Template Tag Parsing Until Another Template Tag and Saving Contents Shortcut for Simple Tags Inclusion Tags Writing Custom Template Loaders Configuring the Template System in Standalone Mode What's Next?

8 xil CONTENTS CHAPTER 1 o Advanced Models Related Objects Accessing Foreign Key Values Accessing Many-to-Many Values Making Changes to a Database Schema Adding Fields Removing Fields Removing Many-to-Many Fields Removing Models Managers Adding Extra Manager Methods... : Modifying Initial Manager QuerySets Model Methods Executing Raw SOL Queries What's Next? CHAPTER 11 Generic Views Using Generic Views Generic Views of Objects Extending Generic Views Making "Friendly" Template Contexts Adding Extra Context Viewing Subsets of Objects Complex Filtering with Wrapper Functions Performing Extra Work What's Next? CHAPTER 12 Deploying Django Preparing Your Codebase for Production Turning Off Debug Mode Turning Off Template Debug Mode Implementing a 404 Template Implementing a 500 Template Setting Up Error Alerts Setting Up Broken Link Alerts Using Different Settings for Production DJANGO_SETIINGS_MODULE PART 3 CHAPTER 13 Usi1 Usi1 Sea Per Wh Ge ThE Pro Ger

9 CONTENTS xiii PART 3 Using Django with Apache and mod_python Basic Configuration Running Multiple Django Installations on the Same Apache Instance Running a Development Server with mod_python Serving Django and Media Files from the Same Apache Instance Error Handling Handling a Segmentation Fault An Alternative: mod_wsgi Using Django with FastCGI FastCGI Overview.~ Running Your FastCGI Server Using Django with Apache and FastCGI FastCGI and lighttpd Running Django on a Shared-Hosting Provider with Apache Scaling Running on a Single Server Separating Out the Database Server Running a Separate Media Server Implementing Load Balancing and Redundancy Going Big Performance Tuning There's No Such Thing As Too Much RAM Turn Off Keep-Alive Use Memcached Use Memcached Often Join the Conversation What's Next? Other Django Features CHAPTER 13 Generating Non-HTML Content The Basics: Views and MIME Types Producing CSV Generating PDFs Installing Reportlab Writing Your View Complex PDFs

10 xiv CONTENTS Other Possibilities The Syndication-Feed Framework Initialization A Simple Feed A More Complex Feed Specifying the Type of Feed Enclosures CHAPTER 15 Language URLs Publishing Atom and RSS Feeds in Tandem The Sitemap Framework Installation ~ Initialization Sitemap Classes Shortcuts Creating a Sitemap Index Pinging Google What's Next? CHAPTER 14 Sessions, Users, and Registration Cookies Getting and Setting Cookies The Mixed Blessing of Cookies Django's Session Framework Enabling Sessions Using Sessions in Views Setting Test Cookies Using Sessions Outside of Views CHAPTER 16 When Sessions Are Saved Browser-Length Sessions vs. Persistent Sessions Other Session Settings Users and Authentication Enabling Authentication Support Using Users Logging In and Out limiting Access to Logged-in Users limiting Access to Users Who Pass a Test Managing Users, Permissions, and Groups Using Authentication Data in Templates

11 CONTENTS xv Permissions, Groups, and Messages Permissions Groups Messages What's Next? CHAPTER 15 Caching Setting Up the Cache Memcached Database Caching Filesystem Caching Local-Memory Caching Dummy Caching (for Development) Using a Custom Cache Back-End CACHE_BACKEND Arguments The Per-Site Cache The Per-View Cache Specifying Per-View Cache in the URLconf Template Fragment Caching The Low-Level Cache API Upstream Caches Using Vary Headers Controlling Cache: Using Other Headers Other Optimizations Order of MIDDLEWARE_CLASSES What's Next? CHAPTER 16 django.contrib The Django Standard Library Sites Scenario 1: Reusing Data on Multiple Sites Scenario 2: Storing Your Site Name/Domain in One Place How to Use the Sites Framework The Sites Framework's Capabilities CurrentSiteManager How Django Uses the Sites Framework Flatpages Using Flatpages Adding, Changing, and Deleting Flatpages Using Flatpage Templates

12 xvi CONTENTS Redirects Using the Redirects Framework Adding, Changing, and Deleting Redirects CSRF Protection A Simple CSRF Example A More Complex CSRF Example Preventing CSRF Humanizing Data apnumber intcomma intword J ordinal Markup Filters What's Next? CHAPTER 18 lnt1 lnte lnte lnte Wh< CHAPTER 19 lnt 1 Hov CHAPTER 17 Middleware What's Middleware? Middleware Installation Middleware Methods lnitializer: _ init_(self) Request Preprocessor: process_request(self, request) View Preprocessor: process_view(self, request, view, args, kwargs) Response Postprocessor: process_response(self, request, response) Exception Postprocessor: process_exception(self, request, exception) Built-in Middleware Authentication Support Middleware "Common" Middleware Compression Middleware Conditional GET Middleware Reverse Proxy Support (X-Forwarded-For Middleware) Session Support Middleware Sitewide Cache Middleware Transaction Middleware What's Next? CHAPTER 20 Ho Hov Usi The Tr Not ge Wh Se The Sat Cro Cro Ses

13 CONTENTS xvii uest) view, , f, Ware) chapter 18 Integrating with Legacy Databases and Applications Integrating with a Legacy Database Using inspectdb Cleaning Up Generated Models Integrating with an Authentication System Specifying Authentication Back-Ends Writing an Authentication Back-End Integrating with Legacy Web Applications What's Next? chapter 19 lnternationalizatim How to Specify Translation Strings In Python Code In Template Code Working with Lazy Translation Objects How to Create Language Files Message Files Compiling Message Files How Django Discovers Language Preference Using Translations in Your Own Projects The set_language Redirect View Translations and JavaScript The javascript_catalog View Using the JavaScript Translation Catalog Creating JavaScript Translation Catalogs Notes for Users Familiar with gettext gettext on Windows What's Next? CHAPTER 20 Security The Theme of Web Security SOL Injection The Solution Cross-Site Scripting (XSS) The Solution Cross-Site Request Forgery Session Forging/Hijacking The Solution

14 xviii CONTENTS Header Injection The Solution Directory Traversal The Solution Exposed Error Messages The Solution A Final Word on Security What's Next? PART 4 Appendixes APPENDIX A Model Definition Reference Fields AutoField BooleanField CharField CommaSeparatedlntegerField DateField DateTimeField Decimal Field Field FileField FilePathField FloatField lmagefield lntegerfield IPAddressField NuiiBooleanField PositivelntegerField PositiveSmalllntegerField Slug Field SmalllntegerField TextField Time Field URLField XMLField APPENDIX B