Show Menu
Cheatography
  1. Home >
  2. Cheat Sheets >

RubyForBeginners Cheat Sheet by

Ruby on Sinatra Using The Twitter API

Ruby Variables

local variable
local_­var­iable
instance variable
@insta­nce­_va­riable
class variable
@@clas­s_v­ariable
global variable
$globa­l_v­ariable

Ruby Data Types

String
 
"­Seq­uence of charac­ter­s."
or 
'Sequence of charac­ters.'
Symbol (ident­ifier)
 
:a_symbol, :anoth­er_­symbol, :name
Integer
 
42, 100, 1002, -256
Float (floating point)
 
1.1, 3.1415926, 5.5, -128.6
Numeric Methods
 
+, -, *, /, %
Comparison Operators
 
==, !=, >, >=, <, <=
Return Value
Last line of a ruby method­/bl­ock­/ex­pre­ssion in IRB
Boolean
 
true
or 
false
 
nil
counts as false in Ruby, everything counts as true
Array (0 indexed)
 
letters = ["a", "­b", "­c"]
 
letters[2]
#returns "­c"
 
letters[1] = "­mon­key­"
 
["a", "­mon­key­", "­c"]

ERB

ERB
Embedded Ruby for making dynamic HTML templates
 
erb :hello
Sinatra looks in "­vie­ws" folder for hello.erb file
Show @tweets
<% if @tweets %> <% @tweet­s.each do |tweet| %> <p>­<%= tweet %><­/p> <% end %> <% end %>
Instance Variables
Any instance variables you declare in your routes, will be accessible in these erb files

Ruby Expres­sions

seen_it = "seen again"
Save string to variable
 
num = 3
Save integer to variable
 
other_num = 5
Save another integer to another variable
 
answer = (num + other_num) * 6
Save result of adding­/mu­lti­plying.

String Interp­olation

dog_speak = "­woo­f!"
 
puts "Dogs say #{dog_­spe­ak}­"
or
 
puts "Dogs say " + dog_speak

Condit­ionals

if/else
 
if input == admin_­pas­sword
  
admin_­log­ged_in = true
  
else
  
puts "­Sorry, wrong passwo­rd."­
  
end

Useful Ruby Methods

split
Breaks a string into an array.
 
join
Takes an array and joins into a string.
 
upcase
Makes characters capital letters.
 
reverse
Reverse characters in a string.
 
sample
Randomly choose element.
 
map
Do the same thing to every element.

Research

Cmd+Click (Mac) or Ctrl+Click
Open links in new tabs.
ruby-d­oc.org ("The Ruby Docs")
Ruby coding best practices.
Stack Overflow
Oops. Research your error.
Guides and blog posts
Has someone done this before?
 

Sinatra

Sinatra
Framework for building a web server written in Ruby
Routing
Action taken in response to request
Path
text and slashes after domain
http:/­/lo­cal­hos­t:4­567­/hello
Sinatra looks for 
get '/hello'
  
get '/hello' do
  
#code to return a response to the browser
  
end
String Response
 
get '/hello'
  
"­Hello, friendly web travel­er!­"
  
end
HTML File Response
 
get '/hello' do
  
erb :hello
  
end
Get tweets route
 
get '/' do
  
@tweets = $clien­t.u­ser­_ti­mel­ine.map { |tweet| tweet.text }
  
erb :index
  
end
 
Redirect '/'
Get server to run code in get '/' route

Array Methods

push
Add to end of array: 
letters << "­ele­pha­nt"
or 
letter­s.p­ush­("el­eph­ant­")
 
<<
Shovel operator. Push to end of array.
 
unshift
Add element to beginning of array: 
letter­s.u­nsh­ift­("ze­bra­")
 
pop
Remove from end of array. 
letter­s.pop
 
shift
Remove from start of array. 
letter­s.shift
 
.metho­d(a­rgu­ments)
Call a method with arguments. Some methods require no arguments.
 
letter­s.pop
Method without arguments.

Hashes

Instan­tiate a Hash (hash rockets)
 
person = {:name => "­Lau­ren­", :age => 89, :sex => "­fem­ale­"}
Instan­tiate a Hash (shortcut)
 
person = {name: "­Lau­ren­", age: 89, sex: "­fem­ale­"}
Access value by key.
 
person­[:name]  # returns "­Lau­ren­"
Update value by key.
 
person­[:age] = 12
Insert key, value pair.
 
person­[:g­ender] = "cis female­"
Remove value by key.
 
person.de­let­e(:sex)  # returns "­fem­ale­"

Methods

Greeting Method Accepts Name
 
def create­_gr­eet­ing­(name)
  
return "­Wel­come, #{name­}"
  
end
Call Greeting Method
 
create­_gr­eet­ing­("La­ure­n")
  
#returns 'Welcome, Lauren­"
Upcase On Call To Greeting Method
 
create­_gr­eet­ing­("La­ure­n").u­pcase
Arguments
Input given to methods.
Parameters
Define what can be passed to a method.
Return value
Output from a function
Implicit Return
Returning last line of method without explicit "­ret­urn­"
 

Command Line

Ruby gems
Download, install, and use ruby software packages on your system
 
$ ruby -v
Get Ruby Version
 
$ irb
Load up intera­ctive Ruby
 
$ gem install sinatra
Install sinatra gem
 
$ gem install twitter
Install twitter gem
 
$ ruby server.rb
Tell Ruby interp­reter to run code.
Ctrl+C
Stop server from running.

Web and HTTP

Server
has IP address, processes requests made by the (client) browser
HTTP
protocol enabling commun­ication between clients and servers
HTTP Verbs
 
GET, POST, PUT, PATCH, DELETE
GET
Request Tweets­(data) from Twitter API
POST
Submit Tweet(­data) to Twitter API
https:
scheme
twitte­r.com
domain
lauren­_n_­rot­h/s­tat­us/­699­996­428­429­561856
path
Params hash
 
params­[:t­weet]

Loops

times
 
10.times do
  
puts "­Hel­lo!­"
  
end
times loop with counter
 
10.times do |counter|
  
puts "­#{c­oun­ter­}"
  
end
 
each 
letters = ["a", "­b", "­c"]
  
letter­s.each do |letter|
  
puts "­Letter #{lett­er}­"
  
end
 
map
 
capita­l_l­etters = letter­s.map do |letter|
  
letter.upcase
  
end
block style
 
letter­s.each { |letter| puts "­Upcase #{lett­er.u­pc­ase­}!" }
elegant map method
 
capitals = letter­s.map { |letter| letter.upcase }

Twitter API

Download files
bit.ly­/db­c-t­wit­ter­-si­natra
Sign Up To Use Twitter API
apps.t­wit­ter.com
Create New App
1. Create new App 2. Create Access Tokens 3. Ensure permis­sions are read/write
Set up Twitter $client global variable
 
require twitter
  
$client = Twitte­r::­RES­T::­Cli­ent.new do |config|
  
config.co­nsu­mer_key        = "­YOU­R_C­ONS­UME­R_K­EY"   config.co­nsu­mer­_secret     = "­YOU­R_C­ONS­UME­R_S­ECR­ET"   config.ac­ces­s_token        = "­YOU­R_A­CCE­SS_­TOK­EN"   config.ac­ces­s_t­oke­n_s­ecret = "­YOU­R_A­CCE­SS_­SEC­RET­"
  
end
Get user timeline
 
$clien­t.u­ser­_ti­meline
Send tweet
 
$clien­t.u­pda­te(­"omg I am tweeting from the command line. So cool!")
 

Metadata

  • Languages:
  • Published: 25th February, 2016
  • Last Updated: 12th May, 2016
  • Rated: 4 out of 5 stars based on 2 ratings

Favourited By

Jota gamliel seidkarl amc538 dhollinger

Comments

No comments yet. Add yours below!

Add a Comment

Your Comment

Please enter your name.

    Please enter your email address

      Please enter your Comment.