iluvruby

Interesting facts about Ruby programming language. Maintained by Milan Dobrota.

[rubyquicktips]

Using Enumerable::inject to modify a hash

Ever wanted to modify the keys and values of a Hash? Enumerable::inject has you covered.

Try this snippet from Stack Overflow:

my_hash = { a: 'foo', b: 'bar' } # => {:a=>"foo", :b=>"bar"} a_new_hash = my_hash.inject({}) { |h, (k, v)| h[k.upcase] = v.upcase; h } # => {:A=>"FOO", :B=>"BAR"}

[rubyloveinfo]

New Relic

Install New Relic into your application and get a free RC Helicopter.

[rubyloveinfo]

View source of a method in IRB

There is an awesome gem called method_source (used internally in pry). Example:

Set.instance_method(:merge).source.display # => def merge(enum) if enum.instance_of?(self.class) @hash.update(enum.instance_variable_get(:@hash)) else do_with_enum(enum) { |o| add(o) } end self end

You can also see the comment for a given method!

Set.instance_method(:merge).comment.display # => # Merges the elements of the given enumerable object to the set and # returns self.

In case of a class (singleton) method, replace

instance_method

with just

method

[rubyloveinfo]

Google Chrome extension for iluvruby released!

Google Chrome extension for iluvruby blog is out!!! Latest iluvruby posts now just one click away:

Check it out on Github

[rubyloveinfo]

Excellent introduction to AMQP

Michael Klishin - AMQP model explained

[rubyloveinfo]

Convert object to array

Have you ever been in a situation where you needed a method that does the following:

Converts nil to an empty array

Converts non-array variable n to [n]

Leaves array variable as is

The way to achieve this is using little known method Array()

> Array(nil)  => [] > Array([])  => [] > Array(1)  => [1] > Array([2])  => [2]

[rubyloveinfo]

Disabling transactions in single rspec test (describe block)

In rspec tests in which you have more than one database connection, uncommitted changes made using one connection are visible only through that connection. Rspec starts a transaction before each test and rolls it back at the end so the database is in the clean state for the next test. This can be turned off, in which case you would have to make sure you clean up the database manually if needed. This change can be applied in the scope of a describe block like this: 

describe Klass do self.use_transactional_fixtures = false ... end

[rubyloveinfo]

Add me on Google+

Google+ so far impressed me. Feel free to add me or post a comment with your email if you need an invitation.

[rubyloveinfo]

Ruby Symbols Stay in Memory

In ruby, symbols never get garbage collected. They stay in memory until the process exits. Get all the symbols in memory with the following command:

Symbol.all_symbols

[rubyloveinfo]

Ruby objects to go: Copyrb - Gem for copying and pasting ruby objects

I have written a quick gem that allows you to copy and paste ruby objects across terminals. This gem has been created primarily to simplify the process of copying objects between different rails environments for people that spend a lot of time in the Rails console (like me). Some examples include long strings, or perhaps strings that are hard to copy due to the escaping involved. You might find it handy to copy the ActiveRecord object that has been misbehaving in production, or to copy an array of objects (to seed the test/development database).

Installation is straightforward: gem install copyrb

You will need to require the gem in both (or more) terminals with: require 'copyrb'

first terminal: copy my_object

second terminal: paste #=> my_object

Feel free to check out the source on Github. Mac OSX only (for now).

[rubyflare]

Clean rspec output

[rubyloveinfo]

rubyflare:

I like my rspec progress dots to remain undisturbed by output generated by the application eg puts, restarting/reindexing sphinx, prince. I use the silence_stream rails kernel method to keep things quiet:

silence_stream(STDOUT) { Users.import }

[rubyloveinfo]

Add Routes in Rails Plugins

How to add routes in Rails plugins? Easier than you think. Just create a config/routes.rb file under your plugin root directory and it will be loaded automatically. 

[rubyloveinfo]

Loaded Gems

If you use RubyGems, you can get that information in the following manner:

Gem.loaded_specs.keys

[rubyloveinfo]

Rails 3 Cheat Sheets

I know it's old news, but in case somebody missed it: Rails 3 Cheat Sheets.

[rubyloveinfo]

How To (Temporarily) Disable ActiveRecord Timestamps (updated_at)

ActiveRecord will try to populate updated_at field every time a change on a given model has been persisted to the database. If for any reason (and you should ask yourself if your reasons are valid) you want to disable such functionality for a given class, this is how it's done:

MyModelClass.record_timestamps = false

I usually don't do this in the actual code, but sometimes I use it in the tests to force setting updated_at when date/time mocking gets in your way.

[rubyloveinfo]

Access Old Attribute Values in ActiveRecord Hooks

If you change the attribute on a given ActiveRecord object and then try to access it in one of the hooks (even if it is before_save or before_update) the new value will be returned. However, sometimes you will need to access the old attribute values as well, whether for your application logic or cleanup purposes, and you might be tempted to fetch that value directly from the database, since the changes haven't been persisted yet.

The good news is you don't have to do that. ActiveRecord provides you with an awesome group of methods for exactly this purpose. For every attribute, a method called <attribute>_was will be generated which will contain the old value. So if your attribute name was called username, the new method username_was will be defined. Pretty slick, Rails team.

[rubyloveinfo]

Gem dependencies

Find out about specific gem dependencies by running:

gem dependency gem_name

In case you need to find out the opposite (what gem are dependent on a given gem), there is a very useful website for that.