If in our joke listing template ( index.rhtml) we wanted to display only the first 20 characters of each joke, we might modify the template code to look like this: įirst up, this code loops through all of the jokes in the collection we set up in our controller above. rhtml files is generally limited to short snippets that output dynamic values or loop through sets of records to output a piece of HTML once for each record. rhtml files that contain inline Ruby code, but because most of your application’s logic will be in the model and controller, the code that goes in your. In Rails, you typically build pages using a simple template language called Embedded Ruby (ERb). Once you’ve got the logic of the model right, you’ll want to adjust the Web pages that present the model to the user (the view). It’s easy to be thrown by these after the terseness of most other languages, but when you realise that in Ruby you trade having to remember complicated XML configuration file syntax (common in Java) for these very readable names, you’ll adjust quickly. Very “talking out loud” sounding names like validates_presence_of and validates_uniqueness_of are common in Ruby. a joke must contain text, and that text must be unique) on newly-created or updated jokes that are submitted through the admin interface: class Joke "published = 1") We can also modify our model ( joke.rb) to set up some requirements (e.g. We can then modify the default action (which is called index) in our joke list controller ( jokelist_controller.rb) to display a list of published jokes, instead of all jokes (the default): def = Joke.published_jokes You’d modify the joke.rb file that defines the model for jokes in the database: def self.published_jokesįind(:all, :conditions => "published = 1") Say you want to be able to show only jokes that have been marked for publication. A Rails application is therefore made up of objects based on database records (the model), Web pages to display and edit those objects (the view), and a set of actions that tie the two together (the controller).Įditing the model files lets you control how records are pulled out of the database. Rails follows a Model-View-Controller (MVC) pattern in the code it generates. Application development then becomes a process of slowly modifying and replacing that auto-generated code to get the specialized functionality you want. With this file in place, you can run a command to generate a Rails scaffold, which is a set of auto-generated files that let you display, create, update, and delete database records using a set of Web pages. You can set up separate databases for development, testing, and production: development:
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With this in mind, the first code you write is a little file called database.yml that tells Rails how to connect to your database, so that it can set up all those intelligent defaults. With very few exceptions, the only time you need to write code in Rails is when your needs are different from the most common case. Because you have a database table called posts, and Rails hooks it all up for you. “Where does the variable come from, and how does it get filled with database records?” you might wonder. What this means in practice is that, instead of having to write a bunch of configuration files and standard boilerplate code for every project you undertake, you can simply code to a set of assumptions and all that grunt work will be done for you.Īs a result, the experience of examining Ruby on Rails code for the first time can be bewildering. Ruby on Rails is the poster child for a principle of agile development frameworks: convention over configuration. The following is republished from the Tech Times #128. But what about the code that you do have to write? Since yesterday’s post announcing Ruby on Rails 1.0, a lot of people have chimed in asking what it’s like when you get past the hype. Ruby on Rails got its reputation based on how little code you have to write to get common Web development tasks done.
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