Sample Store Catalog using using Groovy and Grails and the Java Persistence API on Glassfish with MySQL

Posted by caroljmcdonald on July 7, 2008 at 7:54 PM PDT

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grailsexample

Sample Store Catalog using using Groovy and Grails and the Java
Persistence API on Glassfish with MySQL

I modified this href="http://weblogs.java.net/blog/caroljmcdonald/archive/2008/04/sample_store_ca.html">Groovy
and Grails Catalog Sample application to use JPA entity java
classes instead of Groovy domain classes. I followed the steps in
this InfoQ article href="http://www.infoq.com/articles/grails-ejb-tutorial">Grails + EJB
Domain Models Step-by-Step and I was really surprised at how
easy it was !

href="https://techdayscode.dev.java.net/servlets/ProjectDocumentList?folderID=9118&expandFolder=9118&folderID=9118">
download Catalog sample code

Overview of the Technologies and Frameworks in the Sample Application

The
Java Persistence API
provides a POJO-based persistence model for
Java EE and Java SE applications. It handles the details of how
relational data is mapped to Java objects, and it standardizes
Object/Relational (O/R) mapping.

Grails aims to bring the
"coding by convention" paradigm to Groovy. It's an open-source web
application framework that leverages the Groovy language and
complements Java Web development.

Groovy is an agile and dynamic
language for the Java Virtual Machine, it compiles
to Java bytecode, and it combines popular features from
languages such as Smalltalk, Python, and Ruby.

Grails is a
Model-View-Controller based framework that simplifies the development
of web applications by reducing the need for configuration files
and by generating a lot of the things needed in
a database-backed Web application.

src="http://weblogs.java.net/blog/caroljmcdonald/archive/mvc.gif"
style="width: 304px; height: 334px;">

The Sample Application

The sample application displays an online catalog of pets sold in a pet
store. The image below shows the Catalog Listing page, which allows a
user to
page through a list of items
in a store.

src="http://weblogs.java.net/blog/caroljmcdonald/archive/listpet.jpg"
height="532" width="353">

The Model - JPA Entity Classes

The Model is your application's persistent business domain objects.
A JPA Entity
instance represents a row in a database table. Item
is an Entity class -- a typical Java Persistence entity
object -- which maps to an ITEM table that stores the item instances.

The Item
class has a many-to-one relationship
with the Address
class, this is specified using the

 style="color: rgb(153, 0, 0);">@ManyToOne

annotation in
the Item
class and the

 style="font-weight: bold; color: rgb(153, 0, 0);">@OneToMany style="color: rgb(153, 0, 0);">(mappedBy = "address")

annotation
in the Address
entity class shown below:

cellspacing="0">

Code Sample from: style="font-weight: bold;">model\Item.java

package model;

            

// import ....

            

            @Entity style="color: rgb(153, 0, 0);">
            @Table(name = "item")

public class Item
implements Serializable{

    @Id

    private Long id;

    private String name;

    private String description;

    private String imageurl;

    private String imagethumburl;

    private BigDecimal price;

    @ManyToOne(optional
= false)

               
@JoinColumn(name = "address_id")

    private  style="color: rgb(0, 0, 153); font-weight: bold;">Address  style="color: rgb(0, 0, 153); font-weight: bold;">address;

    // getters and
setters ...

 style="color: rgb(0, 0, 153); font-weight: bold;">}

cellspacing="0">

Code Sample from: style="font-weight: bold;">model\Address.java

package model;

            

// import ....

@Entity

@Table(name = "address")

public class  style="color: rgb(0, 0, 153); font-weight: bold;">Address

implements
Serializable

{

    @Id

    private Long id;

    private String street1;

    private String street2;

    private String city;

    private String state;

    private String zip;

    private BigDecimal latitude;

    private BigDecimal longitude;

    private BigInteger version;

                 style="font-weight: bold; color: rgb(153, 0, 0);">@OneToMany style="color: rgb(153, 0, 0);">(mappedBy = "address")

    private Collection< style="color: rgb(0, 0, 153); font-weight: bold;">Item>  style="color: rgb(0, 0, 153); font-weight: bold;">items ;

// getters and setters ...

   style="color: rgb(0, 0, 153); font-weight: bold;">

}

src="http://weblogs.java.net/blog/caroljmcdonald/archive/classrel.gif"
height="134" width="274">

SQL Sample for items table style="font-family: monospace;">



CREATE TABLE item (

 id BIGINT NOT NULL,

 product_id BIGINT NOT NULL,

 name VARCHAR(30) NOT NULL,

 description VARCHAR(500) NOT NULL,

 imageurl VARCHAR(55),

 imagethumburl VARCHAR(55),

 price DECIMAL(14,2) NOT NULL,

 address_id BIGINT NOT NULL,

 primary key (id),

 foreign key (address_id) references address(id),

 foreign key (product_id) references product(id)

);

Using the Java Persistence API With Grails and MySQL

Entering the Grails command

[prettify]> grails create-app catalog[/prettify]
creates a standard directory structure for a grails application named
catalog. After you have your directory structure , to use JPA
entities with a grails application:

copy your entity files into the application name style="font-weight: bold;">\src\java
directory, in this case I copied the model.Item and the
model.Address java files into the catalog\src\java\model
directory.
copy the MySQL jdbc driver mysql-connector-java-5.1.6-bin.jar
into the directory catalog\lib
.

modify the DataSource.groovy
file in the catalog\grails-app\conf
directory to use MySQL as the data base and the GrailsAnnotationConfiguration
class to use the annotations in the JPA entities as shown below :

cellspacing="0">

Code Sample from: catalog\grails-app\conf style="font-weight: bold;">\DataSource.groovy

 

          import
org.codehaus.groovy.grails.orm.hibernate.cfg.GrailsAnnotationConfiguration

dataSource {

     style="font-weight: bold; color: rgb(153, 0, 0);">configClass =
GrailsAnnotationConfiguration.class

    pooled = false

    driverClassName =
"com.mysql.jdbc.Driver"

    username = "root"

    password = ""

    dialect =
"org.hibernate.dialect.MySQL5InnoDBDialect"

}

hibernate {

    cache.use_second_level_cache=true

    cache.use_query_cache=true

   
cache.provider_class='org.hibernate.cache.EhCacheProvider'

}

// environment specific settings

environments {

    development {

        dataSource {

            dbCreate =
"update"

             style="font-weight: bold;">url = "jdbc:mysql://localhost/petcatalog"

        }

    }

    test {

        dataSource {

            dbCreate =
"update"

            url =
"jdbc:mysql://localhost/petcatalog"

        }

    }

    production {

        dataSource {

            dbCreate =
"update"

            url =
"jdbc:mysql://localhost/petcatalog"

        }

    }

}

In order for Grails to recognize the JPA Entity classes as domain
classes, add the hibernate.cfg.xml file shown
below to the catalog\grails-app\conf\hibernate directory:

cellspacing="0">

Code Sample from: catalog\grails-app\conf\hibernate style="font-weight: bold;">\hibernate.cfg.xml

 <?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE hibernate-configuration PUBLIC

        "-//Hibernate/Hibernate
Configuration DTD 3.0//EN"

      
 "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

          

<hibernate-configuration>

    <session-factory>

        <mapping package="model"
/>

        <mapping
class="model.Item" />

        <mapping
class="model.Address" />

    </session-factory>

</hibernate-configuration>

The Controller



Entering the Grails command  (in the directory catalog)
> grails 
generate-controller
 class="userinput"> model.Item

will generate the ItemController.groovy
class for the model.Item
entity class.

Controllers handle incoming http requests, interact with the model to
get data and to process requests, invoke the correct view, and
direct domain data to the view for display.
In Grails, http requests are handled by Controller classes which
are made up
of one or more action methods that are executed on request and then
either render
a Groovy Server Page or redirect to another
action. Grails routes requests to the controller action which
corresponds to the URL mapping for the request. In Grails the default
mapping from URL to action method follows this convention: http://host/ style="font-weight: bold;">app/controller/action/id . For
example the URL http://host/catalog/item/list
calls the
list style="font-family: monospace; font-weight: bold;"> style="color: rgb(0, 0, 153);"> style="font-weight: bold;">action method in the style="font-weight: bold;"> item controller style="font-family: monospace;"> style="color: rgb(0, 0, 153); font-weight: bold;">class
shown below. href="http://grails.codehaus.org/Scaffolding">Grails
Scaffolding provides a series of standardized
Controller action methods for listing, showing, creating, updating, and
deleting
objects of a class. These standardized actions
come with both controller logic and default view Groovy Server Pages.
The style="color: rgb(0, 0, 153); font-weight: bold;">ItemController
style="color: rgb(0, 0, 153); font-weight: bold;">list
action renders a view with a paginated list of item objects.

Code Sample from: grails-app\ style="font-weight: bold;">controllers\ItemController.groovy

class ItemController
{

def index = {
redirect(action:list,params:params) } style="font-family: monospace;">

def list = {

if(!params.max) params.max = 10

[ itemList: Item.list( params ) ]

}

. . .

When a URL has a controller but no action (e.g.
http://localhost:8080/catalog/item/ ), Grails defaults to the
index action. In the style="font-weight: bold;"> style="font-family: monospace;"> style="color: rgb(0, 0, 153); font-weight: bold;">ItemController
code the style="color: rgb(0, 0, 153); font-weight: bold;"> style="font-family: monospace;"> style="color: rgb(0, 0, 153); font-weight: bold;">index
action method redirects to the style="color: rgb(0, 0, 153); font-weight: bold;">list
action. The style="color: rgb(0, 0, 153); font-weight: bold;">ItemController
style="color: rgb(0, 0, 153); font-weight: bold;">list action
method calls the style="color: rgb(0, 0, 153); font-weight: bold;">Item.list() method
which returns an ArrayList of item objects retrieved from the item
database table . If there are more than style="font-family: monospace;">params.max objects in the
table, Grails creates next and previous pagination links automatically.
The itemList style="font-family: monospace;"> variable is
automatically made available to the view by the framework.

After executing
code, actions usually render a GSP in the views directory
corresponding to the name of the controller and action, for example the
list action will render the grails-app\views\item\list.gsp .

The View

Entering the Grails command (in the directory catalog)
[prettify]> grails generate-views model.Item[/prettify]
will generate the create.gsp ,
edit.gsp, list.gsp, show.gsp groovy server pages for the style="font-weight: bold;">model.Item entity class.

The view layer generates a web
page, using data from domain objects provided by the controller. In
Grails, the view is rendered using href="http://docs.codehaus.org/display/GRAILS/Developer+-+Groovy+Server+Pages">Groovy
Server Pages. Below is part of the list.gsp for the Catalog
application (note I modified the html table format from the default
generated).

Code Sample from: grails-app\ style="font-weight: bold;">views\item\list.gsp



<table>

   <thead>

     <tr>

         style="color: rgb(0, 0, 153); font-weight: bold;"><g:sortableColumn
property="name" title="Name" />

        <g:sortableColumn
property="imagethumburl" title="Photo" />

        <g:sortableColumn
property="price" title="Price" />

     </tr>

   </thead>

   <tbody>

      style="color: rgb(0, 0, 153); font-weight: bold;"><g:each
in="${itemList}"
status="i"
var="item">

        <tr class="${(i % 2) == 0
? 'odd' : 'even'}">

           <td>

            
      <g:link
action="show" id="${item.id}">

               
${item.name?.encodeAsHTML()}</g:link>

           </td>

           <td>

            
<img src="${createLinkTo(dir:'images',file: style="color: rgb(0, 0, 153); font-weight: bold;">item.imagethumburl)}"/>

           </td>

          
<td>${item.price?.encodeAsHTML()}</td>

        </tr>

     </g:each>

  </tbody>

 </table>

      

<div class="paginateButtons">

 <g:paginate
total="${Item.count()}" />

</div>

The view uses instance variables set by the controller to
access the data it needs to render the GSP.

GSP has a GroovyTagLib similar to the JSP tag library. <g: are
GroovyTags.

<g:sortableColumn

The href="http://grails.codehaus.org/GSP+Tag+-+sortableColumn">sortableColumn
tag renders a sortable column to support sorting in tables.

<g:each
in="${itemList}" status="i"
var="item">

loops through each object in the itemList style="font-family: monospace;"> variable,
which is an ordered style="font-weight: bold;">ArrayList of

 style="color: rgb(0, 0, 153); font-weight: bold;">Item

model
objects, and assigns each

 style="color: rgb(0, 0, 153); font-weight: bold;">Item

model object to the

 style="color: rgb(0, 0, 153); font-weight: bold;">item

variable.

<g:link
action="show"
id="${item.id}">${item.name?.encodeAsHTML()}</g:link>

 href="http://grails.org/doc/1.0.x/ref/Tags/link.html">the
<g:link>

GroovyTag creates an html anchor tag href
based on the action, id, controller
parameters specified. In this example it generates a link to the
item/show/id action which when clicked will display the
corresponding item details. For
example this line will generate the following HTML for the variable item:

<a class="attribute-name"> href="/catalog/item/show/2">Friendly Cat</ class="end-tag">a>

<img
src="${createLinkTo(dir:'images',file:item.imagethumburl)}"/>

style="color: rgb(0, 0, 153); font-weight: bold;">

The href="http://docs.codehaus.org/display/GRAILS/Tag+-+createLinkTo">createLinkTo
tag generates an HTML link for the

item's
imagethumburl

 style="color: rgb(0, 0, 153); font-weight: bold;">

attribute.

${item.price?.encodeAsHTML()}

displays the value of the

 style="color: rgb(0, 0, 153); font-weight: bold;">item 's price

attribute
as
escaped HTML text.

<g:paginate
total="${Item.count()}" />

The href="http://grails.codehaus.org/GSP+Tag+-+paginate">paginate tag
creates next/previous buttons and a breadcrumb trail to allow
pagination of results using the Item.count()
domain method.

The Show Action Method

In Grails the mapping for the URL http://host class="attribute-value">/item/show/1 (
http://host/controller/action/id
) will
route to the style="color: rgb(0, 0, 153); font-weight: bold;">show
action in the style="color: rgb(0, 0, 153); font-weight: bold;">ItemController
passing 1 to the method as the style="color: rgb(0, 0, 153); font-weight: bold;">id of
the style="color: rgb(0, 0, 153); font-weight: bold;">params parameter
hash. The style="color: rgb(0, 0, 153); font-weight: bold;">show
action of the style="color: rgb(0, 0, 153); font-weight: bold;">ItemController class
is shown below. The style="color: rgb(0, 0, 153); font-weight: bold;">ItemController
style="color: rgb(0, 0, 153); font-weight: bold;">show
action renders a view showing the details of the item object
corresponding to the id parameter.

Code Sample from: grails-app\controllers\ItemController.groovy

def show = {

   def item = style="color: rgb(0, 0, 153); font-weight: bold;">Item.get( style="color: rgb(0, 0, 153); font-weight: bold;">params.id )

   if(!item) {

      flash.message = "Item not found with id
${params.id}"

      redirect(action:list)

   }

   else { return [ item : item ] }

}

The style="color: rgb(0, 0, 153); font-weight: bold;">show
action method calls the style="color: rgb(0, 0, 153); font-weight: bold;">Item.get()
style="color: rgb(0, 0, 153); font-weight: bold;">

 style="font-family: monospace;"> style="color: rgb(0, 0, 153); font-weight: bold;">method
which queries the items table returning the style="font-family: monospace;">  style="font-family: monospace;"> style="color: rgb(0, 0, 153); font-weight: bold;">item instance
variable corresponding to the item with the attribute  style="font-family: monospace;"> style="color: rgb(0, 0, 153); font-weight: bold;">id
(primary key)
equal to the   style="color: rgb(0, 0, 153); font-weight: bold;">id
parameter. This is the equivalent of the following sql :  style="font-family: monospace;">select * from items where id=' style="font-family: monospace;"> style="color: rgb(0, 0, 153); font-weight: bold;">1' .
The  style="color: rgb(0, 0, 153); font-weight: bold;">item variable
is automatically made available to the Show view by the framework. style="font-weight: bold;">




The Show View GSP


After executing
code in the action, the  style="color: rgb(0, 0, 153); font-weight: bold;">show action
renders the app/views/item/show.gsp . Below is the GSP for
the item show view : 






  
    
      
    
    
      Code Sample from: grails-app\ style="font-weight: bold;">views\item\show.gsp 
  

<h2> Detail of item</h2>

      

<table>

<tbody>

    <tr class="prop">

      <td valign="top"
class="name">Name:</td>                          
      

      <td valign="top"
class="value">${item.name}</td>                          
      

   
</tr>                   
      

    <tr class="prop">

        <td valign="top"
class="name">

          
Description:

       
</td>                           
      

        <td valign="top"
class="value">

          
${item.description}

       
</td>                          
      

   
</tr>                       
      

    <tr class="prop">

        <td valign="top"
class="name">Imageurl:</td>                          
      

        <td valign="top"
class="value">

           
<img src="${createLinkTo(dir:'images',file: style="color: rgb(0, 0, 153); font-weight: bold;">item.imageurl)}"
/>

       
</td>                           
      

   
</tr>                                           
      

    <tr class="prop">

        <td valign="top"
class="name">Price:</td>                           
      

        <td valign="top"
class="value">$
${item.price}</td>                           
      

    </tr>

    <tr class="prop">

        <td valign="top"
class="name">Address:</td>                           
      

        <td valign="top"
class="value">

         
${item?.address?.street1},
${item?.address?.city},    
      

         
${item?.address?.state}

       
</td>                          
      

   
</tr>                       
      

</tbody>

</table>    


      

      






${item.description}

displays the value of the   style="color: rgb(0, 0, 153); font-weight: bold;">item 's 
description style="color: rgb(0, 0, 153); font-weight: bold;"> 
attribute.


<img
src="${createLinkTo(dir:'images',file:item.imageurl)}" />
 style="color: rgb(0, 0, 153); font-weight: bold;"> 
generates an HTML

image tag for the  style="color: rgb(0, 0, 153); font-weight: bold;">item's imageurl


attribute.




${item?.address?.city}
displays the value of the   style="color: rgb(0, 0, 153); font-weight: bold;">item's 
 style="font-family: mon;">address city
 style="color: rgb(0, 0, 153); font-weight: bold;"> 
attribute.





The image below shows the resulting page for the url

http://host/catalog/item/show/105, which displays the item 105's

details:




    


 src="http://weblogs.java.net/blog/caroljmcdonald/archive/showpet.jpg"

 height="728" width="677"> 




Layouts
Grails layouts 

let you put common html on multiple views (for

example page headers,  footers, sidebars).  Default layout

templates are in the views layouts directory with a file name

corresponding to the controller, or you can associate a view with a

layout using the "layout" meta tag to your page:

<meta name="layout" content= class="code-quote">"main">


To add a title and parrot image to the

top of the Pet Catalog pages, I put this table in the

app\views\layouts\main.gsp  layout: 







Code Sample from: app/views/layouts/main.gsp








  


   


   


 

Pet Catalog 


     
src="${createLinkTo(dir:'images',file:'pet_logo.jpg')}"/>


   



      

      
 












Conclusion


This concludes the sample application which demonstrates how to work

with Groovy and Grails  to page through a list

of  Item JPA Entities

which are retrieved using Item

Controller action methods, and

displayed using Item View GSPs.






Setting Things Up and Running the Sample code on  style="font-weight: bold;">MySQL and Jetty:



  If MySQL
is already installed, then download  href="https://glassfish.dev.java.net/downloads/v2ur1-b09d.html">GlassFish
v2 UR1. Otherwise you can also Download  href="http://glassfish.java.net/">GlassFish v2 UR1
and MySQL co-bundle
from the usual Download
Page ( href="http://docs.sun.com/app/docs/doc/820-3797/ggkei?l=en&q=mysql&a=view">instructions).
    

    

  

  Download and
install Grails.

    

  

  Download the  href="http://techdayscode.dev.java.net/servlets/ProjectDocumentList?folderID=8159">sample
code and extract its contents. You should now see the newly
extracted directory as <sample_install_dir>/Catalog
,

where <sample_install_dir> is the directory where

you unzipped the sample package. For example, if you extracted the

contents to C:\ on a Windows machine, then your newly

created directory should be at C:\Catalog.  


The

file 

"/Catalog/grails-app/conf/DataSource.groovy"

is configured

for a MySQL

configuration.


    

  
Start the MySQL database as follows:


    


> mysqld_safe --user root
--console


        

      


 Create the pet-catalog database:


    


> mysqladmin
create petcatalog --user root


        
 href="http://dev.mysql.com/doc/refman/5.0/en/batch-commands.html">


         



 href="http://dev.mysql.com/doc/refman/5.0/en/batch-commands.html">Create

the tables in the MySQL pet-catalog database as follows:


    



        [prettify]shell&gt; mysql <em class="replaceable"><code>pet-catalog<em class="replaceable"><code> < </code></em>catalog.sql[/prettify]
      

using the file catalog.sql file from the /Catalog

directory. 

        

      

    

  

  Run the project as follows:

in a command window in the /Catalog directory enter the command 

  

  
    > grails run-app

This will run the Application using the built-in Jetty Servlet engine.

When you run the project, your browser should display the Catalog home
page at http://localhost:8080/catalog/ .

Run the Sample code on Glassfish:

Use the WAR file in
<sample_install_dir>/Catalog/Catalog.war
or Create a WAR file:

[prettify]> grails war[/prettify]

Copy the WAR file (catalog-0.1.war) to your
Glassfish installation "domains/domain/autodeploy"
directory. (Start Glassfish and MySQL if you haven't already)

Enter the URL http://localhost:8080/catalog-0.1/
in
your browser, you should see the home page of the Sample
Application.

For more information:

Grails
+ EJB Domain Models Step-by-Step

To learn how to build a Grails CRUD app see: href="http://blogs.sun.com/arungupta/entry/totd_30_crud_application_using">TOTD
#30: CRUD Application using Grails - Hosted on Jetty and HSQLDB

To learn how to run a Grails app on Glassfish and mySQL
see: href="http://weblogs.java.net/blog/arungupta/archive/2008/04/totd_31_crud_ap.html">TOTD
#31: CRUD Application using Grails - Hosted on GlassFish and MySQL

Grails framework

Groovy

href="http://dev.mysql.com/doc/refman/5.0/en/mysql-commands.html">MySQL
commands

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Sample Store Catalog using using Groovy and Grails and the Java Persistence API on Glassfish with MySQL