Configuring the Application

Rails uses a flat file located in config/database.yml to store the information on how to connect to the database. This file should be edited to look like this:

# MySQL (default setup).  Versions 4.1 and 5.0 are recommended.
#
# Install the MySQL driver:
#   gem install mysql
# On MacOS X:
#   gem install mysql -- --include=/usr/local/lib
# On Windows:
#   There is no gem for Windows.  Install mysql.so from RubyForApache.
#   http://rubyforge.org/projects/rubyforapache
#
# And be sure to use new-style password hashing:
#   http://dev.mysql.com/doc/refman/5.0/en/old-client.html
development:
  adapter: mysql
  database: student
  username:
  password:
  host: localhost

# Warning: The database defined as 'test' will be erased and
# re-generated from your development database when you run 'rake'.
# Do not set this db to the same as development or production.
test:
  adapter: mysql
  database: student_test
  username: root
  password:
  host: localhost

production:
  adapter: mysql
  database: student_production
  username: root
  password:
  host: localhost

Now let us write the maintenance application. In a command window type:
c:/rails/work/student>ruby script/generate scaffold Participant Admin

That single command has written a basic maintenance application. The Participant parameter told the command the name of the model we want, and the Admin parameter specifies the name of the controller. Let's try our application. First, we'll start a local WEBrick-based web server, supplied with Rails. Let's connect to it. Remember, the URL we give to our browser contains both the port number (3000) and the name of the controller in lowercase (admin) ie. http://localhost:3000/admin

It's showing us a list of participants, and there aren't any participants. Let's remedy that. Click the New participant link, and a form should appear. Fill in the details and click on the Create button, you should see the new participant in the list. See the screenshot. The User Interface is not good, but it works. We can show this to our client for his/her approval. The client can play with the other links (showing details, editing existing participants etc.).

Rails Scaffolds
A Rails scaffold is an autogenerated framework for manipulating a model. When we run the generator, we tell it that we want a scaffold for a particular model (which it creates) and that we want to access it through a given controller (which it also creates). In Rails, a model is automatically mapped to a database table whose name is the plural form of the model's class. In our case, we asked for a model called Participant, so Rails associated it with the table called participants. And how did it find that table? We told it where to look when we set up the development entry in config/database.yml. When we started the application, the model examined the table in the database, worked out what columns it had, and created mappings between the database data and Ruby objects. We created the participant maintenance scaffolding in the Admin controller, which is why the URL that accesses it has admin at the start of its path. The scaffold is the starting point of an application, not a finished application. And we're about to make use of that fact as we move on to the next iteration in our project.

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