Rake tasks step by step

01 June 2014

Rake tasks step by step

Rake tasks are placed in lib/tasks directory of application and files have .rake extension

Simple Example

First, you must write a “Rakefile” file which contains the build rules. Here’s a simple example:

task :default => [:test]

task :test do
  ruby "test/unittest.rb"
end

This Rakefile has two tasks:

A task named “test”, which - upon invocation - will run a unit test file in Ruby.
A task named “default”. This task does nothing by itself, but it has exactly one dependency, namely the “test” task. Invoking the “default” task will cause Rake to invoke the “test” task as well.

Running the “rake” command without any options will cause it to run the “default” task in the Rakefile:

% ls
Rakefile     test/
% rake
(in /home/some_user/Projects/rake)
ruby test/unittest.rb
....unit test output here...

Simple greet rake task

# lib/tasks/welcome.rake
task :greet do
 	 puts “Hello !!”
end

## Execute task
rake greet

Adding description to rake task

# lib/tasks/welcome.rake
desc “This is new style of greet”
task :greet do
	puts “Hello !!”
end

## Execute task
rake greet

Adding namespace to rake tasks

It’s nothing but prefix that takes while executing rake task. Benefit of adding namespace is to categories similar rake tasks.

# lib/tasks/welcome.rake
namespace :introduction do
desc “This is one style of introduction”
task :greet do
  puts “Hello !!”
end
desc “This is 2nd style of introduction”
task :hi do
  puts “Hi ”
end
end

## Execute task
rake introduction:greet
rake introduction:hi

Passing arguments to rake tasks

# lib/tasks/welcome.rake

namespace :introduction do
desc “This is one style of introduction”
task :greet do
  puts “Hello !!”
end

desc “This is 2nd style of introduction”
task :hi => :enviroment do
  puts “Hi #{ENV['name']}”
end
end


## Execute task
rake introduction:hi name=Raj

Ruby 14

Rails 7