Book Image

Grails 1.1 Web Application Development

By : Jon Dickinson
Book Image

Grails 1.1 Web Application Development

By: Jon Dickinson

Overview of this book

Web development is trickyóeven a simple web application has a number of context changes ready to trip up the unwary. Grails takes the everyday pain out of web application development, allowing us to focus on delivering real application logic and create seamless experiences that will address the needs of our users. This book will take the pain out of Grails by showing you exactly how to build a web application with a minimum of fuss. With this book, even if you are new to Grails, you will be up and running before you know it. You will be able to code faster and your code will be better. This clear and concise book is packed with examples and clear instructions to help you build your first Grails application and gives you the skills to speed up your application development by adding a different angle for learning about the topic. After a brief introduction to the dynamic JVM-based Groovy programming language, which teaches you enough about Groovy to understand the relationship between Grails and the Groovy scripting language, it shows how to use Grails and a number of key plug-ins to deliver valuable web applications. It also takes you through creating, developing, testing, and deploying an example team collaboration application in Grails. Using an incremental and iterative approach you will learn how to build a basic web application with secure authentication and different levels of authorization. You will learn how to handle file upload allowing users to share files. Some advanced features of object-oriented persistence will be introduced through adding tags for messages and files to giving users a robust categorization system. You will then build on the basic application to enhance the user experience through AJAX and the RichUI plug-in. You will take a further step into the world of Web 2.0 by adding an RSS feed and a REST service to the application. Once the entire application is up and running, you will learn how to create your own plug-in for tagging. Finally, you will learn how to deploy this application to a production environment.

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Grails 1.1 Web Application Development
Jon Dickinson
May, 2009 | 328 pages
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Table of Contents (20 chapters)
Grails 1.1 Web Application Development
Grails 1.1 Web Application Development
Credits
Credits
About the author
About the author
Acknowledgement
Acknowledgement
About the reviewers
About the reviewers
Preface
Preface
Free Chapter
1
Getting Started with Grails
Getting Started with Grails
Why Grails?
Installing Grails
Build a team communication portal
Summary
2
Managing Users with Scaffolding
Managing Users with Scaffolding
What is scaffolding?
Create the domain classes
Creating controllers to enable scaffolding
Control through constraints
Meeting the relations
Bootstrapping demo data
Summary
3
Posting Messages
Posting Messages
Message domain class
Rendering a form
Handling user input
Create a home page
Styles and navigation
Tidying up
Summary
4
Introduction to Groovy
Introduction to Groovy
What is Groovy?
Why Groovy?
Running Groovy
Groovy features
Summary
5
Authentication with JSecurity Plug-in
Authentication with JSecurity Plug-in
Where to find plug-ins
Installing a plug-in
Configuring JSecurity plug-in
Add the missing pieces
JSecurity tags
Who posted that?
Summary
6
Testing
Testing
Writing unit tests
JUnit refresher
Unit tests in Grails
Integration testing
Integration tests in Grails
Functional testing
Functional testing In Grails
Testing guidance
Summary
7
File Sharing
File Sharing
File domain object
FileController
File Upload GSP
Saving the file
Viewing files
Modeling for efficiency
Downloading files
Summary
8
More GORM and Criteria
More GORM and Criteria
More GORM relationships
Querying with criteria
Updating FileController
Render file versions
Fix file download
Summary
9
Services
Services
Introducing services
Implementing FileService
Summary
10
Managing Content through Tagging
Managing Content through Tagging
Add basic tagging
Customize the home page
All Messages and Files
Summary
11
AJAX and RIA Frameworks
AJAX and RIA Frameworks
Edit tags inline
Auto-complete tags
Introducing tag clouds
Summary
12
Searching, RSS, and REST Services
Searching, RSS, and REST Services
Searching
RSS
REST services
Summary
13
Build your own Plug-in
Build your own Plug-in
The tagger plug-in
Using plug-in events
Summary
14
Deployment and the Real World
Deployment and the Real World
Set up the environment
Configure Grails
Hosting options
Next steps
Summary

Modeling for efficiency

The implementation we have for file upload works fine and is easy to understand, but it is also quite naive in terms of efficiency. The problem is that every time a user views the information about a file, all the binary data for the file will be loaded into the memory. By altering our domain model slightly, we can easily improve the performance. We will need a domain class to represent the data as a one-to-one relationship with the File object. We saw in Chapter 5 that relationships between domain objects are lazy by default. This means that, by extracting the data out into its own object, retrieving a list of files will not load the binary data of the file, unless we request it specifically.

Create a new domain class named FileData in the same package as the File domain class:

package app
class FileData {
private static final int TEN_MEG_IN_BYTES = 1024*1024*10
static belongsTo = [file:File]

byte[] data
static constraints = {
data( nullable: false, minSize: 1, maxSize...
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