Ten-Things-You-Didn't-Know-Rails-Could-Do.md

Presenter: James Edward Gray II (@jeg2)

Bio

James (@JEG2) has been a Rails programmer for about as long as it has been fashionable to be one and a Rubyist even longer than that. As you probably know from listening to him on the Ruby Rogues podcast, James loves to dig into how our community and code works.

Abstract

Rails is huge. Even if you have worked with it for a long time, it's unlikely that you have stumbled across everything yet.

Do you really know what all of the built-in Rake tasks do? Have you seen all of the methods ActiveSupport makes available to you? Are you aware of all the queries ActiveRecord is capable of?

In this talk, I'll dig into the extras of Rails and see if I can't turn up some features that you don't see all of the time, but that might just be handy to know about anyway. I'll make sure you come out of this able to impress your friends at the hackfest.

Notes

Really, 42 things.

From @james_gary

• FridayHug.com
• Interfaces - Ways to give Rails a huge
• thesmallestrailsapp.com
• rake notes:todo, or rake notes:fixme
  • rake notes:custom ANNOTATION=JEG2
• Sandbox Your Console
  • rails c --sandbox # rolls back changes
• You can call helper methods in the console
• Use Non-Webrick servers in development
• Allow you to tap into its configuration
  • require Railtie, with config.custom in Railtie
  • You can configure plugins the same way you configure Rails
• Understand Shorthand Migrations
  • Default is string, can add limits
• Add indexes to migrations
• Add associations to a Migration rails g resource article user:references subject body:text rails g resource article user:belongs_to subject body:text
• Show you the status of the db
  • rake db:migrate:status
• Import your csv (see slides)
• Store CSV in your db
• Pluck fields out of your database
  • User.select(:email).map(&:email)
  • User.pluck(:email)
  • User.uniq.pluck(:email)
• Count Records in Groups
• Allow you to override associations
• Instantiate records without a db (tricky, maybe evil)
  • User.instantiate("id" => 42...)
• Use limitless strings in postgresql (see slide)
• Use full text search in postgresql
  • rails g resource article subject body:text
  • t.column :search, "tsvector"
  • CREATE INDEX articles_search_index ON articles USING gin(search);
  • (see slides)
• Use a different database for each user
  • config = ActiveRecord::Base.configurations["development"].merge("database" -> "db/${name}.sqlite3)
  • Reset activerecord
• Intermission
  • Why do this?
    • Trying to give us new ideas
    • Studies show this will help you solve Rails problems
    • It's fun! Remember to have fun
• Refine your fashion sense, @tenderlove
• Ruby extensions - Updating Ruby's fashion sense
• Write Files Atomically
  • File.atomic_write(...)
• Merge Nested Hashes
  • Hash#deep_merge
• Remove specific keys from a hash
  • params.except(:foo, :bar)
• Add defaults to hash
  • reverse_merge
• "foo".inquiry.foo?
  • Can use method_missing to make it natural
• Views
  • Hide comments from your users
  • <%# ERb comments don't show %>
• Understand a shorter erb syntax
  • % foo instead of `<% foo %>
• Use blocks to avoid assignments in view <% calculate_tax @cart.total do |tax| %> (can use tap if you already have value)
• Generate Multiple tags at once
  • content_tag_for(:div, articles)
• Render any object
  • Now, Ruby asks object, not class, how to render
  • render as
• Group menu entries
  • select_tag(::grouped_menu, grouped_options_for_select) Hash
• Build forms the way you like them
  • ActionView::Helpers::FormBuilder
• Inspire theme songs about your work (Ruby Hero Tenderlove on youtube)
• Actions
  • Route Exceptions
    • config.exceptions_app = routes
    • match '/404', to: 'errors#foo'
• Route to Sinatra (see slides)
• Stream CSV to Users
  • format.csv do .. end
  • set headers['Content-Disposition']
• Do some work in the background
  • require 'thread'
• Publish a static site using rails

From @benjaminoakes

• Who
  • He's on Ruby Rogues
  • Rubyist for 8 years
  • Ruby code/documentation
  • CSV
• Rails 3.2.3
• Rails app in a single file
• rake notes for TODO, FIXME, OPTIMIZE
  • rake notes:custom ...
  • TextMate bundle
• Sanbox rails console
  • DB changes reverted
  • rails c --sandbox
• Helper methods in console
  • helper objecdt
• Non-webrick servers in dev: rails s thin
• In Railties: tap into config
  • require first

Database

• Migration shorthand
  • string by default, limits in {})
  • Indexes at command line name:index
  • Associations: user:references or user:belongs_to, column, add_index, and association (belongs_to)
  • rake db:migrate:status tells you whether a migration is applied
• CSV
  • Import CSV data (see slide). @jeg2 gets this all the time
  • CSV in database (use load and dump for serialize)
• Pluck
  • Foo.select(;email).map(&:email) same as Foo.pluck(:email)
• Records in groups Foo.group(:bar).count
• Override associations: def foo=
• Instatiate records without a DB: tell its id, etc Foo.instantiate('id' => 1) #evil
• Limitless strings in PostgeSQL (rather than a text field? I'm confused) FIXME
• Full text search in PostgreSQL: t.column :search, "tsvector" SQL: gin(search) (same as what Sphinx uses)
  • Too quick; see slides FIXME
  • Does stemming, case insensitive
• User in own database
  • SQLite is good for this
  • Uses ActiveRecord.establish_connection (he made a library... user_database?) TODO
  • Need a before_filter or similar
  • Could trigger by by subdomain
  • Not fighting with other users

Ruby

• File.atomic_write (makes a tempfile and moves it into place at the end; not good on NFS)
• Merge nested hashes: Hash#deep_merge in Rails
• Remove keys from a Hash: Hash#except(:foo, :bar)
• Hash#merge overwrites; not good for params, so for defaults, use Hash#reverse_merge
• Predicates on strings. Familiar example: Rails.env.development. "foo".inquiry.magic?. Works well with validates_inclusion_of

Views

• HTML coments or ERb comments. Slower using ERb, but not visible.
• Shorthand ERb: erubis broke: % if foo.bar?. @Jeg2 has a pull request for this. TODO link
• Blocks to avoid assignemnts (each and tap, or write a helper method that takes a block)
• Multiple tags at once with content_tag FIXME I think this isn't quite right
• Render any object using Foo#to_partial_path using render partial: @foo
• Group menu entries: select_tag(...) FIXME missed option name
• Make your own form builder (ActionView::Helpers::FormBuilder). See also default_form_builder and field_error_proc
• @tenderlove's theme song (on YouTube) TODO link

Actions

• Route exceptions to any Rack app
• match '/404', to: 'foo'
• Route to Sinatra. Example: Resque's interface. mount Foo, at: 'bar/baz'
• Stream CSV to users: format.csv and headers["Content-Disposition"] for filename. ANything that responds to each and <<. Use something like Foo.find_each to prevent defeating the purpose. :)
• Background work: Queue.new (threadsafe) and Thread.new. Then find the queue and then append something that has run (e.g., a lambda)
• Publish a static site using Rails. Page cache everything. cache_page(...)
  • Too fast FIXME fill in from slides
  • Spiders and writes everything out
  • Then rsync

From @danbernier

@jeg2 is known as "Mr. Ruby Rogue."

Uh-oh: it's now FORTY-TWO things.

1. Get a hug, every Friday

Interfaces: give Rails a hug

Run a rails app from a single file, under 20 lines.

Find TODOs: rake notes:todo rake notes:fixme rake notes:custom ANNOTATION=foo

TODO blah

foo stuff

---

Sandbox your consolerails c --sandbox

Run Helper Methods in the Console

helper.time_ago_in_words(3.days)

Use non-webrick servers in dev

rails s thin

Custom configuration with Railties ActiveSupport::OrderedOptions.new

Database

Shorthand migrations:

rails g resource user name:index email:uniq token:string{6} bio:text string{6}: a lengith limit :index: adds an index :uniq: adds a unique index

Associations: rails g resource article user:references OR rails g resource article user:belongs_to

rake db:migrate:status - tell you whether a migration has been run

Import your CSV, with headers:true, header_convertions: symbol

Store CSV in your database, with load & ...dump?

Pluck fields out of the database.

User.select(:email).map(&:email) -> User.pluck(:email)

Count records in groups Event.group(:trigger).count: group them, & count 'em up

Let you override associations belongs_to :previous_owner, class_name: "Owner"

Instantiate Records w/o a database User.instantiate('id' => 1, 'email' => 'j@ex.com')

Use limitless strings in postgresql ...something like, :delete_limit?

Use Full Text Search in Postgresql

rails g resource article subject bodi:text Use "tsvector" type in your migration Uses a generic inverted index plainto_tsquery('english', ?) -- postgres function for queriing it It does stemming for you.

Use a different database for each user. You end up having to connect to it in each controller action, so you're hitting the right database for each request.

---

Why do this?

• To give us new ideas
• It's fun!

---

Ruby Extensions

Updating Ruby's fashion sense

Atomic file writes File.atomic_write { |f| f.puts 'um' }

Merge nested hashes Hash#deep_merge

Remove specific Keys from a Hash Hash#except(:key1, :key2)

Add defaults to a Hash Hash#reverse_merge

Answer questions about strings "magic".inquiry.magic? #-> true

Views

Hide comments from your users with <%# ERb comments %>

Use a shorter ERb syntax % if current_user.try(:admin?) <%= render "edit_links" %> % end ...but you have to include PercentLineEnhancer into Erubis. The whole line has to be ruby, and it's all removed from the output.

Use blocks to avoid assignment in views. Write helper methods to a) do your math for you, and b) yield the value to a block. Delimits the scope of the variable. (You can also use #tap.)

Generate multiple tags at once. content_tag_for(:div, @article) now operates on collections.

Render any object: class MyModel def to_partial_path "not_my_normal_model_path" end end render :partial as ('as' is the important bit)

Group menu entrieswith grouped_options_for_select

Subclass ActiovView::Helpers::FormBuilder, and then... f.labeled_text_field_with_errors :my_attribute (You have to add these methods.)

---

@tenderlove has a THEME SONG???

Route Exceptions the rails router is a rack application, so then: match "/404"...

Route to Sinatra (for APIs) ...and he gave some kind of authorization example that I kind of missed.

Stream CSV to users with format.csv, and headers['Content-Dispostion']

Do some work in the background require 'thread' @thread ||= THread.new do while job = queue.pop job.call end end ...(rest of the example) But you can queue up just a plain old lambda. That's pretty nice.

Publish a static site using rails - cache everything, then he has a rake task that touches earch page on the site. (This one included to ensure EVERYONE learned something from the talk.)

Slides are coming online, at http://speakerdeck.com/u/jeg2

@zachmorek

42 things you didn't know

On Rail 3.2.3

1- Friday hugs

Rails application in one File TODO / FIXME / OPTIMIZE - rake task Sandboxing console Non WEBrick Servers... rails s thin Tap into config

rake db:migrate status User.uniq.pluck(:email) Event.group.count

Full text search in postgres

Different database for each user Atomic file writing - file.atomic_write("#{id}.txt") Deep merge of hashes someHash.except(:user_id) Erb comments

=======

From @skalnik

• Annontated comments rake notes
• Sandbox mode: rails c --sandbox
• Shorthand migrations: rails g resource user name email token:string{6} => rails g resource user:string name:string email:string …
• Specify indexes in command line migration rails g
• rails g resource article user:references => Adds foreign key & index for ya
  • Also understands belongs_to if you don't like references
• rake db:migrate:status
• Import CSV data by just converting each row into a hash
• You can store CSV in DB if you create a simple serializer
• User.select(:email).map(&:email) => User.pluck(:email)
• You can override association methods and then invoke the normal one via super
• Instantiate reocrds w/o DB if you want to set ID or something: User.instantiate(<# Hash>)
• Postgres doesn't have to have a limit on string length, but Rails tries to use one. Can be configured to turn off
• Use full text search in postgres. Uses same algorithm as Sphinx!
• Multi-DB apps are not too difficult (find link for code)
• Write files atomically: File.atomic_write
• Merge nested hash with deep_merge
• ERB comments <%# %> disappear on compile (Users can never see it)
• Shorter ERB syntax:

    % if current_user.try(:admin?)
      <%= render "edit_links" %>
    % end

• Multiple tags at once with content_tag_for(:div, @articles)
• to_partial_path in your object will allow you to change partial path for it
• grouped_options_for_select lets you group select input
• Can make custom form builders by inheirting from ActionView::Helpers::FormBuilder and config.action_view.default_form_builder
• Can route exceptions to a Rack app (That's how Rails does it internally!)
• Can use constraints in routes to validate user is admin (Crafting Rails Apps)
• Mount rack app like resque server
• Do work in background by spawning off a thread that pulls from a simple in-app queue (Crafting Rails Apps)
• Generate static sites by telling it to cache ALL the things, then spider it & dump files
• "I feel so bad for the people trying to take notes"

External Links

• Friday hugs
• Slides
• The Smallest Rails app