Arun Gupta's Blog

Database-enabled Hello World RoR app

UPDATE: Simplified steps for GlassFish V2 are available here and for V3 here.

In this post I show how a Rails app can talk to database. Here are the steps I followed:

1. Deploy a RoR application as WAR on GlassFish using these steps.
2. Modify the application such that "Hello World!" is read from the controller instead of defined in the view (this is natural to RoR programmers anyway!).
   1. Define a new variable in controller as '@hello_string = "Hello World!"'.
   2. Replace the string in view with '<%= @hello_string %>'.
3. Download and install MySQL Community Server 5.0 and MySQL Connector/J 5.0.5.
4. Create database using the command: 'mysqladmin -u root create helloworld_development'.
5. Right select the NetBeans project, select 'Generate', select 'model', specify the arguments as 'table1', click 'OK'. This will generate, in NetBeans project, Database Migrations, migrate, 001_create_table1s.rb.
6. Open 001_create_table1s.rb, change self.up helper method such that it looks like:

   def self.up
     create table :table1s do |t|
       t.column :data, :string
     end
   end

7. Right-select NetBeans project, select 'Run Rake Target', 'db', 'migrate'. This generates the appropriate database tables.
8. In NetBeans Runtime tab, right click on 'Databases', 'New Connection ...'.
   1. In Name, select 'New Driver ...' and specify the location of mysql-connector-java-5.0.5-bin.jar from the MySQL Connector/J installation directory.
   2. In Database URL, give 'jdbc:mysql://localhost:3306/helloworld_development'.
   3. Expand the newly added database node, expand Tables, right-select 'table1s', select 'Execute Command ...'.
   4. Enter the following SQL "insert into table1s values (1, 'Hello from database')". Run the SQL.
9. Change the controller such 'hello_string' is initialized from the database. This is a contrived example but still convey the concept. Anyway, The code looks like:
   
   @hello_string = Table1.find(1).data
10. Start MySQL database by giving the following command:
    
    mysqld --console
11. Save all the files and refresh the page in the browser. If your controller name is 'say' and view is 'hello', then the URL will be 'http://localhost:3000/say/hello'. The browser will now display 'Hello from database'.

In a later post, I'll describe how this same application can be deployed as WAR in GlassFish V2.

Technorati: glassfish rubyonrails ror netbeans

Comments

• I'm so grateful for all that you've done. Thanks again for that nice essay and I would be most grateful if you would send me the latter ones....

  
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  Posted by: jklmno on June 19, 2008 at 09:37 AM

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