1.2. Putting Rails
into Action
You could manually install all of the components
for Rails, but Ruby has something called gems. The gem installer accesses a web
site, Ruby Forge, and downloads an application unit, called a gem,
and all its dependencies. You can install Rails through gems,
requesting all dependencies, with this command:
gem install rails --include-dependencies
That's itRails is installed. There's one caveat:
you also need to install the database support for your given
database. If you've already installed MySQL, you're done. If not, go to http://rubyonrails.org for more
details on Rails installation. Next, here's how to create a Rails
project:
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In the mid-1970s, the MVC
(model-view-controller) strategy
evolved in the Smalltalk community to reduce coupling between
business logic and presentation logic. With MVC, you put your
business logic into separate domain objects and isolate your
presentation logic in a view, which presents data from domain
objects. The controller manages navigation between views, processes
user input, and marshals the correct domain objects between the
model and view. Good programmers have used MVC ever since,
implementing MVC applications using frameworks written in many
different languages, including Ruby.
Web developers use a subtly different variant of
MVC called Model2. Model2 uses the
same principles of MVC but tailors them for stateless web
applications. In Model2 applications, a browser calls a controller
via web standards. The controller interacts with the model to get
data and validate user input, and then makes domain objects
available to the view for display. Next, the controller invokes the
correct view generator, based on validation results or retrieved
data. The view layer generates a web page, using data provided by
the controller. The framework then returns the web page to the
user. In the Rails community, when someone says MVC, they're
referring to the Model2 variant.
Model2 has been used in many successful projects
spread across many programming languages. In the Java community,
Struts is the most common Model2 framework. In Python, the flagship
web development framework called Zope uses Model2. You can read
more about the model-view-controller strategy at http://en.wikipedia.org/wiki/Model-view-controller.
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>rails chapter-1
create
create app/controllers
create app/helpers
create app/models
create app/views/layouts
create config/environments
create components
create db
create doc
create lib
...
create test/mocks/development
create test/mocks/test
create test/unit
create vendor
...
create app/controllers/application.rb
create app/helpers/application_helper.rb
create test/test_helper.rb
create config/database.yml
...
We truncated the list, but you get the
picture.
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