Developing a Sample Website using Grails Framework

Hello again! :)

Today I'm showing you the most basic things we can do with Grails. In last post we installed Grails and now let's find out how to create a small sample website using it.

1. Creating demoapp

Open cmd prompt or terminal and navigate to a place where you would like to create your first grails app. For my convenience I create my app inside the grails folder I used to install grails in last post.

grails create-app demoapp

This command will create an app called "demoapp". After creating you will see a url like this - http://localhost:8080/demoapp/ in the command prompt (or the terminal). Type the url in the browser and you will see a page like following.

Default Grails App Home Page

If you go inside the demoapp folder you will see following folder structure.

So let's start coding!

2. Creating domain classes

Run following command in cmd/terminal. You should be located inside the created demoapp directory. Mine is C:\grails\demoapp

grails create-domain-class Student

Now if you go to your demoapp/grails-app/domain directory you will see there is a new folder created named demoapp (same name as our app). Inside that folder there will be a new Student.groovy file. that is the domain class we just created. If you open it with a text editor you'll see a code like this.

package demoapp

class Student {
        static constraints = {
    }

We'll create two more domain classes to demonstrate our app.

grails create-domain-class School
grails create-domain-class Subject

Let's modify the code now.

Student.groovy

package demoapp

class Student {

 String firstName
 String lastName
 School school
 Date created
 
 static hasMany = [subjects:Subject]
 static belongsTo = School
 
 static constraints = {
  firstName(nullable:false)
  lastName(nullable:false)
  school(nullable:false)
  created(nullable:false)
 }
}

School.groovy

package demoapp

class School {
 String name
 String address
 Date created
 
 static hasMany = [students:Student, subjects:Subject]
 
 static constraints = {
  name(nullable:false)
  address(nullable:false)
  created(nullable:false)
 }
}

Subject.groovy

package demoapp

class Subject {
 String subjectCode
 String subjectName
 Date created
 
 static belongsTo = [school:School]
 
 static constraints = {
  subjectCode(nullable:false)
  subjectName(nullable:false)
  created(nullable:false)
 }
}

3. Creating controllers and views

After coding the demo classes you should create the controllers and the views. In order to do that you can use "generate-all" command (refer documentation to learn the other available commands).

grails generate-all demoapp.School
grails generate-all demoapp.Subject
grails generate-all demoapp.Student

After doing above steps you will see in the project folder that the new controller files and views have been created with default methods and layouts. :)

Finally, when you run the app your first page will be like this.

If you click on the links and check out the inside of the app you will see the required forms and lists and all other spices have been already added by Grails itself. :)

3. Configuring our application to MySQL database

Since Grails is built on Java technology setting up a data source requires a JDBC driver. If you use a database other than H2 you'll need that respective driver. For example for MySQL we would need Connector/J.
So download the latest Connector/J (I used: mysql-connector-java-5.1.21.zip) and extract the JAR file (Mine is: mysql-connector-java-5.1.21-bin.jar) to demoapp/lib directory.

Create a new database called demoapp using MySQL. Don't create the tables, grails will do that for you :)

Now change the DataSource.groovy file in demoapp/grails-app/conf folder as follows (Remember these are only the minimum changes required. You can change other things also. But be knowledgeable before changing anything.)

dataSource {
    pooled = true
    driverClassName = "com.mysql.jdbc.Driver"
    username = "root"
    password = ""
}
hibernate {
    cache.use_second_level_cache = true
    cache.use_query_cache = false
    cache.region.factory_class = 'net.sf.ehcache.hibernate.EhCacheRegionFactory'
}
// environment specific settings
environments {
    development {
        dataSource {
            dbCreate = "update" // one of 'create', 'create-drop', 'update', 'validate', ''
            url = "jdbc:mysql://localhost:3306/demoapp"
        }
    }
    test {
        dataSource {
            dbCreate = "update"
            url = "jdbc:mysql://localhost:3306/demoapp"
        }
    }
    production {
        dataSource {
            dbCreate = "update"
            url = "jdbc:mysql://localhost:3306/demoapp"
            pooled = true
            properties {
               maxActive = -1
               minEvictableIdleTimeMillis=1800000
               timeBetweenEvictionRunsMillis=1800000
               numTestsPerEvictionRun=3
               testOnBorrow=true
               testWhileIdle=true
               testOnReturn=true
               validationQuery="SELECT 1"
            }
        }
    }
}

Also remember here I have used the same url for all 3 environments. But in a real environment you would probably want to define a different database for each one or at least for production use.

Then uncomment the mysql dependency in the grails-app/conf/BuildConfig.groovy file to as follows.

...
dependencies {
    // specify dependencies here under either 'build', 'compile', 'runtime', 'test' or 'provided' scopes eg.

    runtime 'mysql:mysql-connector-java:5.1.21'
}
...

Go back to the command line and type "grails clean". Then run the app.

grails clean
grails run-app

Now check your MySQL databases using command line tool or phpMyAdmin or even MySQL workbench. You will see that grails crated the database structure for you.

So from now on when you save data using the application those data will be saved permanently in your database.

You can go on developing your website like this. Main things we do when creating our own site are:

• Change the css files (style the site as our need)
• Change the design according to our requirements
• Change the application logic
• Use appropriate plugins to get the work done
• etc.

So major things regarding starting off a fresh web site using Grails Framework is done here. But you have lot more to do if you are developing a real world product.

I hope to cover some more areas I have already touched in Grails in the future. Till then, Happy Coding!!! /bye