03-21-16-introduction_to_sinatra.md

Sinatra

Ruby gem
Domain-specific language (DSL)
minimal effort Ruby library that makes HTTP access and simple web apps easy
Much more light weight than rails so more suitable for smaller simpler applications.

Things about Sinatra

modular vs classic style
Rack-compatible
config.ru file

Web Guesser File structure

Mimics Rails organizational structure using MVC (Model, View, Controller)

Sinatra project folder
- Server file
- Views folder
  - erb files

Server File

Contains routing with HTTP verbs (GET, POST, PUT, DELETE)
Client says GET me something from...
- example.com/ --> get '/'
- example.com/people --> get '/people'
- example.com/posts --> get '/posts'
What you put in your server file determines what the client gets back.

Routing in Server file

get '/' do
  #stuff to be done
  erb :index # which erb file to render
end

Sending Variables to Views

Instance Variables

get '/' do
  @number = 8
  erb :index
end

Local Variables

get '/' do
  number = 8
  erb(:index, locals => { :variable_in_view => variable_in_server })
  # the key :variable_in_view is the name of the variable in the 
  # erb file the value it is pointing to is the actual variable you 
  # want to send.
end

Views in Sinatra

Server file specifies which view to send back to client
Views are .erb files (Embedded RuBy)
Interprets any ruby and sends back pure HTML to client

embed Ruby code in HTML using the below syntax

<% ruby_code_here %>

embed Ruby code you want display in HTML using the below syntax

<%= ruby_code_here %>

Example HTML with ERB

    <html>
      <head>
      </head>
      <body>
        <%= ruby_variable %>
      </body>
    </html>

Forms in HTML

    <form>
      <input type="text" name="firstname">
      <input type="text" name="lastname">
      <input type="submit" value="Click here!">
    </form>

Data submitted by user in a form comes in as a hash called "params"
The input the user typed on line 2 can be accessed in your server file as params[:firstname]
The input the user typed on line 3 can be accessed in your server file as params["lastname"]

notice that you can use strings or symbols for your key names

Accessing Params in Routes

    get '/dashboard' do
      @name = params["firstname"]
      erb :dashboard
    end

jwashke/03-21-16-introduction_to_sinatra.md