ruby with jendiamond: April 2014

Wednesday, April 30, 2014

Instance Variables

http://www.railstutorial.org/book/rails_flavored_ruby#sec-a_user_class
In Rails, the principal importance of instance variables is that they are automatically available in the views, but in general they are used for variables that need to be available throughout a Ruby class.

Instance variables always begin with an @ sign, and are nil when undefined.

initialize, is special in Ruby: it’s the method called when we execute User.new.

https://www.ruby-lang.org/en/documentation/quickstart/2/

class Greeter
def initialize(name = "World")
@name = name
end
def say_hi
puts "Hi #{@name}!"
end
def say_bye
puts "Bye #{@name}, come back soon."
end
end

@name is an instance variable, and is available to all the methods of the class.

http://rubymonk.com/learning/books/4-ruby-primer-ascent/chapters/45-more-classes/lessons/110-instance-variables

http://www.rubyist.net/~slagell/ruby/instancevars.html

An instance variable has a name beginning with @, and its scope is confined to whatever object self refers to. Two different objects, even if they belong to the same class, are allowed to have different values for their instance variables. From outside the object, instance variables cannot be altered or even observed (i.e., ruby's instance variables are never public) except by whatever methods are explicitly provided by the programmer. As with globals, instance variables have the nil value until they are initialized.

Instance variables do not need to be declared. This indicates a flexible object structure; in fact, each instance variable is dynamically appended to an object when it is first assigned.

***http://rubyhacking.andhapp.co.uk/2011/01/30/chapter-1.html

Monday, April 28, 2014

RVM

Assumed knowledge

Don't type in the <> Just put whatever you want to use in there like the particular Rails version.
Don't type in the $ This means type it in your terminal.

$ rvm list - lists rubies

rvm rubies

ruby-1.9.3-p545 [ x86_64 ]
ruby-2.0.0-p451 [ x86_64 ]
=* ruby-2.1.1 [ x86_64 ]
# => - current # =* - current && default # * - default

$ rvm use ruby 2.1.0-p547 (p means patch)

$ rvm gemset list

gemsets for ruby-2.1.1 (found in /home/user/.rvm/gems/ruby-2.1.1)
(default)
global

L
rvm gemset use <rails 4.0>

rvm gemset create <name> - (for example: name = rails -v 4.0.4)
L
rvm gemset use

rvm install
L
rvm use <ruby>

Thursday, April 24, 2014

Yield

http://www.ruby-doc.org/core-2.1.1/Fiber.html

Fiber
Fibers are primitives for implementing light weight cooperative concurrency in Ruby. Basically they are a means of creating code blocks that can be paused and resumed, much like threads. The main difference is that they are never preempted and that the scheduling must be done by the programmer and not the VM.
As opposed to other stackless light weight concurrency models, each fiber comes with a small 4KB stack. This enables the fiber to be paused from deeply nested function calls within the fiber block.
When a fiber is created it will not run automatically. Rather it must be be explicitly asked to run using the Fiber#resume method. The code running inside the fiber can give up control by calling Fiber.yield in which case it yields control back to caller (the caller of the Fiber#resume).
Upon yielding or termination the Fiber returns the value of the last executed expression

yield(args, ...) → obj
Yields control back to the context that resumed the fiber, passing along any arguments that were passed to it. The fiber will resume processing at this point when resume is called next. Any arguments passed to the next resume will be the value that this Fiber.yield expression evaluates to.

http://stackoverflow.com/questions/3066703/blocks-and-yields-in-ruby

http://www.tutorialspoint.com/ruby/ruby_blocks.htm

Presenter Object

http://robots.thoughtbot.com/post/13641910701/ti dy-views-and-beyond-with-decorators

http://blog.steveklabnik.com/posts/2011-09-09-better-ruby-presenters
I hate not understanding a joke: Dijkstra's Algorithm

http://railscasts.com/episodes/287-presenters-from-scratch

http://stackoverflow.com/questions/20503445/using-presenters-ryan-bates-style-without-an-associated-model

http://eewang.github.io/blog/2013/09/26/presenting-the-rails-presenter-pattern/

Presenter is a Design Pattern
http://pivotallabs.com/presenter-sanity/
http://stackoverflow.com/questions/7860301/rails-patterns-decorator-vs-presenter

http://en.wikipedia.org/wiki/Model%E2%80%93view%E2%80%93presenter

Model–view–presenter (MVP) is a derivative of the model–view–controller (MVC) architectural pattern, also used mostly for building user interfaces.
In MVP the presenter assumes the functionality of the "middle-man" (played by the controller in MVC, although it must not be assumed that the presenter and controller play the same role). In MVP, all presentation logic is pushed to the presenter. Eventually, the model becomes strictly a domain model.

(The domain model is a conceptual model of all the topics related to a specific problem. It describes the various entities, their attributes, roles, and relationships, plus the constraints that govern the problem domain.) http://en.wikipedia.org/wiki/Domain_model

Presenter and Decorator in Rails Slideshare

http://www.slideshare.net/thaichor/presenter-and-decorator-in-rails

Now to take a break with a Bundler Core Team favorite, Bee and PuupyCat!

Wednesday, April 23, 2014

Chapter 4 Crafting Rails 4 Applications

I am stuck just trying to run rails plugin new handlers

First of all there is a typo on page 64 There should NOT be a dash in between plug and in

I did a lot of rvm management and now I am getting a openssl error
$ dpkg -l | grep openssl

Dave suggested that I check out:
https://groups.google.com/forum/#!topic/laruby-books/C1u-wZAYvHw
This didn't work

Cynthia suggested I install rvm

Interesting links people mentioned:
http://designinstruct.com/tool/responsive-html-email-framework-zurb-ink/

http://prose.io/

Rails Conf
http://www.railsconf.com/

Tuesday, April 22, 2014

more FB

Checked out the Facebook debugger.
URL Decoder

A canonical link element is an HTML element that helps webmasters prevent duplicate content issues by specifying the "canonical", or "preferred", version of a web page as part of search engine optimization.

Looked at the metadata for the Page
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>_________X | Official Shop of _________X </title>
<meta name="description" content="_________X">
<meta name="keywords" content="_________X">
<meta property="og:title" content="_________X" />
<meta property="og:url" content="https://_________X.com/"/>
<meta property="og:image" content="https://cloudfront.net/assets/logo_color_small.png"/>
<meta property="og:description" content= "_________X"/>
<meta content="_________X.com" name="host" />
<meta content="_________X" name="_________X" />
<meta content="authenticity_token" name="csrf-param" />
<meta content="_________X=" name="csrf-token" />

**Noticed that the meta content for the og:url and the og:image are wrong.
The og:image goes to https://cloudfront.net/assets/logo_color_small.png which is the small logo.

For the og:url
We wrote a new method in the application_helper
def current_path
request.original_url
end
Changed the meta property in the metadata partial

For the og:image
We wrote a new method in the application_helper
def current_crowdshop_image
current_inventory.cover.file
end
Changed the meta property in the metadata partial

Ideas

<meta content="inventories" name="stock[type]" />
request.original_url
original_url() publicReturns the original request URL as a String.

# get "/articles?page=2"

request.original_url # => "http://www.example.com/articles?page=2"

url_for( only_path: false )

Another idea...
app/views/crowdshops/_socialbar.html.erb
change...
u=

app/decorators/stock_decorator.rb

def to_facebook
CGI.escape(to_url)
end
def to_twitter
{
url: to_url,
via: "_________X",
text: "Look at this awesome design!",
related: h.current_metadata.twitter_id
}.to_query
end
def to_pinterest
{
url: to_url,
media: cover.file,
description: "#{name} by #{author}"
}
end

--------------------------------------------------------------
escape(string)
URL-encode a string.

url_encoded_string = CGI::escape("'Stop!' said Fred")
# => "%27Stop%21%27+said+Fred"
------------------------------------------------------------------

Layouts and Rendering in Rails

K is having me read: http://guides.rubyonrails.org/layouts_and_rendering.html
To understand what this is doing: <%= render partial: "file/metadata" %>

I already know that it is embeded ruby and with the inclusion of the = sign it prints whatever is in there to the view but what am I missing that is wrong?

The render method
render - read the files interprets the filepath

ActionController::Base#render https://gist.github.com/jcasimir/1210155

The render method is very overloaded in Rails. Most developers encounter it within the view template, using render :partial => 'form' or render @post.comments, but here we'll focus on usage within the controller. http://api.rubyonrails.org/classes/ActionView/PartialRenderer.html

partial - doesn't wrap (on either side) the contents in the layout file
Partial templates - usually just called "partials" - are another device for breaking the rendering process into more manageable chunks. With a partial, you can move the code for rendering a particular piece of a response to its own file.

A partial can use its own layout file, just as a view can use a layout.

http://guides.rubyonrails.org/layouts_and_rendering.html

Controller and View in the Model-View-Controller The Controller is responsible for orchestrating the whole process of handling a request in Rails, though it normally hands off any heavy code to the Model. But then, when it's time to send a response back to the user, the Controller hands things off to the View. It's that handoff that is the subject of this guide.

Controllers in Rails automatically render views with names that correspond to valid routes.

The rule is that if you do not explicitly render something at the end of a controller action, Rails will automatically look for the action_name.html.erb template in the controller's view path and render it.

Structuring Layouts
When Rails renders a view as a response, it does so by combining the view with the current layout, using the rules for finding the current layout that were covered earlier in this guide. Within a layout, you have access to three tools for combining different bits of output to form the overall response:

Asset tags

auto_discovery_link_tag
javascript_include_tag
stylesheet_link_tag
image_tag
video_tag
audio_tag

yield and content_for
Partials

My Ah ha moment:

I had copied and pasted the exact same information into the file as was being rendered by <%= render partial: "file/metadata" %> So it was there twice in different forms.

Friday, April 18, 2014

Styles

Use this for code blocks
<div style="background: #cfc; border: solid 1px #096; padding: 5px 5px 5px 5px;">
code block
</div>

test

test

Use this when quoting large areas of text
<blockquote>
<div style="background: #b9ffff; border: solid 1px #096; padding: 5px 5px 5px 5px;">
code block
</div>
</blockquote>

test

test

MIME Types and Magic Numbers

MIME Types

Multipurpose Internet Mail Extensions (MIME) is an Internet standard that extends the format of email to support:

character sets other than ASCII
Non-text attachments
Message bodies with multiple parts
Header information in non-ASCII character sets

Magic Numbers

In computer programming, the term magic number has multiple meanings. It could refer to one or more of the following:

A constant numerical or text value used to identify a file format or protocol; for files, see List of file signatures
Distinctive unique values that are unlikely to be mistaken for other meanings (e.g., Globally Unique Identifiers)
Unique values with unexplained meaning or multiple occurrences which could (preferably) be replaced with named constants

How could a magic number be bad?

Thursday, April 17, 2014

Block Procs Lambdas map&:(to_s) &:

How &: works? if it is a method, and where is it defined? > It is rails addition to ruby obviously. http://caboo.se/doc/classes/Symbol.html#M003931 Symbol#to_proc This is tricky thing to document. It exploits a ruby syntax quirk where prepending a & to a method argument calls "to_proc" on that object in an attempt to make it eligible to be a block. v.map(&:to_s) Is the same as: v.map { |i| i.to_s } https://www.ruby-forum.com/topic/154453 http://www.reactive.io/tips/2008/12/21/understanding-ruby-blocks-procs-and-lambdas/

Wednesday, April 16, 2014

algorithms

Algorithm - a small procedure that solves a recurrent problem.

What is a computer algorithm?

To make a computer do anything, you have to write a computer program. To write a computer program, you have to tell the computer, step by step, exactly what you want it to do. The computer then "executes" the program, following each step mechanically, to accomplish the end goal.

When you are telling the computer what to do, you also get to choose how it's going to do it. That's where computer algorithms come in. The algorithm is the basic technique used to get the job done. Let's follow an example to help get an understanding of the algorithm concept.

Let's say that you have a friend arriving at the airport, and your friend needs to get from the airport to your house. Here are four different algorithms that you might give your friend for getting to your home:

The taxi algorithm:

Go to the taxi stand.
Get in a taxi.
Give the driver my address.

(continue to site...)

http://algorithms.openmymind.net/

Top 10 Algorithms for Coding Interview

Videos
http://www.computerscienceforeveryone.com/Course_1/Unit_13/Lesson_1/

http://www.scifac.ru.ac.za/javabook/ch02.htm

SORTING ALGORITHMS IN RUBY, PART 1

Algorithm LargestNumber
Input: A non-empty list of numbers L.
Output: The largest number in the list L.
largest ← L0
for each item in the list (Length(L)≥1), do
if the item > largest, then
largest ← the item
return largest

Ruby Projects

https://www.learnstreet.com/lessons/study/ruby#get-hint

Pinterest, FB

The issue I have is to make sure the FB link posts a photo of the product and the url to it.

References:
https://developers.facebook.com/docs/reference/fql
https://developers.pinterest.com/pin_it/

Sharing with FaceBook
https://developers.facebook.com/docs/web/share
Publishing rich and structured Custom Stories, for example a story about cooking a meal, running a race, or reading a book:

FB has a few ways that you can provide these:

Social Plugins such as the Like and Share Buttons let people quickly recommend pieces of content to various audiences on Facebook. Social Plugins simply require copy and pasting a couple of bits of HTML, and are the easiest way for developers to get sharing into their apps, with no Facebook Login required.
The Feed Dialog, which can be invoked via the JavaScript SDK or through URL redirection, allows people to share content using a consistent UI that matches that of Facebook. You also don't need to implement Facebook Login to use the Feed Dialog, which makes it simpler for developers.
The Graph API can be used for any of these types of sharing, and is the only way to use Custom Stories on the web. This can offer more control of the sharing experience by letting you build your own UI, but requires that Facebook Login is also implemented.

Can I use the Share Dialog without using the Share Button?

Yes, although we recommend using the Share button to offer the simplest and most consistent experience for people using your site, you can invoke the Share Dialog using a link:
<a href="https://www.facebook.com/sharer/sharer.php?u=https%3A%2F%2Fparse.com" target="_blank">
Share on Facebook
</a>

**********************************
Add a _metadatafile to designs inventories and downloads directories
**********************************

_metadata.html.erb

app/helpers/application_helper.rb

def facebook_link_to(url)
open_to facebook_icon, "#{FACEBOOK_SHARE_URL}?#{{ u: url }.to_query}", class: "btn btn-info"
end

def twitter_link_to(text, url, via, related)
open_to twitter_icon, "#{TWITTER_SHARE_URL}?#{{ text: text, url: url, via: via, related: related }.to_query}", class: "btn btn-primary"
end

def pinterest_link_to(description, url, media = nil)
open_to pinterest_icon, "#{PINTEREST_SHARE_URL}?#{{ description: description, url: url, image: image, media: media }.to_query}", class: "btn btn-danger"
end

FACEBOOK_SHARE_URL = "https://www.facebook.com/sharer/sharer.php"
TWITTER_SHARE_URL = "https://twitter.com/share"
PINTEREST_SHARE_URL = "http://pinterest.com/pin/create/button"

----------------------------------------------------------------
to_query(key) public
----------------------------------------------------------------
Converts an array into a string suitable for use as a URL query string, using the given key as the param name.

['Rails', 'coding'].to_query('hobbies') # => "hobbies%5B%5D=Rails&hobbies%5B%5D=coding"

Facebook Debugger

Enter a URL to see some helpful feedback about your page markup. Enter an access token to see its expiry and user.

SOLUTION:

Add the metadata into the download and the design directories.

Side Note:
Chrome Developers Tools Tutorials

Tuesday, April 15, 2014

ssh

I have been trying to push changes to rubilicious for a while unsuccessfully. I kept getting the error: fatal: Authentication failed
VonC on StackOverflow had my answer which was to switch to an ssh url:
git remote set-url origin git@github.com:rubilicious/rubilicious.github.io.git

Friday, April 11, 2014

Heartbleed Bug Fixes

The Heartbleed Bug

The Heartbleed Bug is a serious vulnerability in the popular OpenSSL cryptographic software library. This weakness allows stealing the information protected, under normal conditions, by the SSL/TLS encryption used to secure the Internet. SSL/TLS provides communication security and privacy over the Internet for applications such as web, email, instant messaging (IM) and some virtual private networks (VPNs).
The Heartbleed bug allows anyone on the Internet to read the memory of the systems protected by the vulnerable versions of the OpenSSL software. This compromises the secret keys used to identify the service providers and to encrypt the traffic, the names and passwords of the users and the actual content. This allows attackers to eavesdrop on communications, steal data directly from the services and users and to impersonate services and users.

Things I had to do to fix it:

0. Update my Open SSL (which I did yesterday)

1. $ rvm implode Ignore this message:

Failed to completely remove /home/jen/.rvm -- You will have to do so manually.
Note you may need to manually remove /etc/rvmrc and ~/.rvmrc if they exist still.
Please check all .bashrc .bash_profile .profile and .zshrc for RVM source lines and delete or comment out if this was a Per-User installation.
Also make sure to remove `rvm` group if this was a system installation.
Finally it might help to relogin / restart if you want to have fresh environment (like for installing RVM again).

2. remove ssh secrets
remove all authorizations from github security
$ rm ~/.ssh/id_rsa ~/.ssh/id_rsa.pub

3. Remove all ssh keys from Github and
any other permissions in Security and Applications section

4. regenerate ssh keys
$ ssh-keygen -t rsa -C <"myname@email.com">

Generating public/private rsa key pair.Enter file in which to save the key (/home/jen/.ssh/id_rsa): (hit Enter/Return for default)
Enter passphrase (empty for no passphrase): (hit Enter/Return for default or add pswd)
Enter same passphrase again: (hit Enter/Return for default or add pswd again)
Your identification has been saved in /home/jen/.ssh/id_rsa.Your public key has been saved in /home/jen/.ssh/id_rsa.pub.The key fingerprint is: blah blah blah

5. get rid of ruby on computer

6. get a password manager for ubuntu

KeePassX saves many different information e.g. user names, passwords, urls, attachments and comments in one single database. For a better management user-defined titles and icons can be specified for each single entry. Furthermore the entries are sorted in groups, which are customizable as well. The integrated search function allows to search in a single group or the complete database.
KeePassX offers a little utility for secure password generation. The password generator is very customizable, fast and easy to use. Especially someone who generates passwords frequently will appreciate this feature.

Task for today:

K is pushing a branch I need to download it and test it

Thursday, April 10, 2014

Notes - Rails Tutorial Chapter 2 & Ubuntu Updates

Did an upgrade of all my Ubuntu packages including Open SSL

OpenSSL could be made to expose sensitive information over the network, possibly including private keys.

Neel Mehta discovered that OpenSSL incorrectly handled memory in the TLS
heartbeat extension. An attacker could use this issue to obtain up to 64k
of memory contents from the client or server, possibly leading to the
disclosure of private keys and other sensitive information.

rails console vs irb

The exact prompt you'll see in irb can vary and I see the same one you do in Rails 3. It's nothing to worry about. In fact, I see the simple prompt in plain irb, and the full prompt in rails console :-)

They are both irb, it's just that rails console is set up such that the rails environment is all set and ready to work with, while regular irb has almost nothing loaded by default.

Controller

A controller is a Ruby class which inherits from ApplicationController and has methods just like any other class. When your application receives a request, the routing will determine which controller and action to run, then Rails creates an instance of that controller and runs the method with the same name as the action.

Request methods

An HTTP 1.1 request made using telnet. The request, response headersand response body are highlighted.

HTTP defines methods (sometimes referred to as verbs) to indicate the desired action to be performed on the identified resource. What this resource represents, whether pre-existing data or data that is generated dynamically, depends on the implementation of the server. Often, the resource corresponds to a file or the output of an executable residing on the server. The HTTP/1.0 specification^[10]^{:section 8}defined the GET, POST and HEAD methods and the HTTP/1.1 specification^[1]^{:section 9} added 5 new methods: OPTIONS, PUT, DELETE, TRACE and CONNECT. By being specified in these documents their semantics are well known and can be depended upon. Any client can use any method and the server can be configured to support any combination of methods. If a method is unknown to an intermediate it will be treated as an unsafe and non-idempotent method. There is no limit to the number of methods that can be defined and this allows for future methods to be specified without breaking existing infrastructure. For example, WebDAV defined 7 new methods and RFC5789 specified the PATCH method.

GET: Requests a representation of the specified resource. Requests using GET should only retrieve data and should have no other effect. (This is also true of some other HTTP methods.)^[1] The W3C has published guidance principles on this distinction, saying, "Web application design should be informed by the above principles, but also by the relevant limitations."^[11] See safe methods below.
HEAD: Asks for the response identical to the one that would correspond to a GET request, but without the response body. This is useful for retrieving meta-information written in response headers, without having to transport the entire content.
POST: Requests that the server accept the entity enclosed in the request as a new subordinate of the web resource identified by the URI. The data POSTed might be, as examples, an annotation for existing resources; a message for a bulletin board, newsgroup, mailing list, or comment thread; a block of data that is the result of submitting a web form to a data-handling process; or an item to add to a database.^[12]
PUT: Requests that the enclosed entity be stored under the supplied URI. If the URI refers to an already existing resource, it is modified; if the URI does not point to an existing resource, then the server can create the resource with that URI.^[13]
DELETE: Deletes the specified resource.
TRACE: Echoes back the received request so that a client can see what (if any) changes or additions have been made by intermediate servers.
OPTIONS: Returns the HTTP methods that the server supports for the specified URL. This can be used to check the functionality of a web server by requesting '*' instead of a specific resource.
CONNECT: Converts the request connection to a transparent TCP/IP tunnel, usually to facilitate SSL-encrypted communication (HTTPS) through an unencrypted HTTP proxy.^[14]^[15] See HTTP CONNECT Tunneling.
PATCH: Is used to apply partial modifications to a resource.^[16]

HTTP servers are required to implement at least the GET and HEAD methods^[17] and, whenever possible, also the OPTIONS method.^{[citation needed]}

Resources

A resource is simply the object the user of the application will interact with.

Rails Tutorial Chapter 8.20

current_user=

First, you're reading the method names wrong (which is not surprising given how cryptic ruby method naming can be). def current_user=(user) is actually read as defining the method current_user= that takes an argument user, whereas def current_user defines a method current_user that takes no arguments. These are referred to respectively as setters and getters.

Setters and getters are like attr accessor and attr reader.

Github: https://github.com/activerecord-hackery/squeel
Documentation: http://rubydoc.info/gems/squeel/1.1.1/frames
Railscast: http://railscasts.com/episodes/354-squeel?view=asciicast

Squeel lets you write your Active Record queries with fewer strings, and more Ruby, by making the Arel awesomeness that lies beneath Active Record more accessible.

acts-as-taggable-on

Github: https://github.com/mbleigh/acts-as-taggable-on
Documentation: http://rubydoc.info/gems/acts-as-taggable-on/3.1.1/frames
Railscast: http://railscasts.com/episodes/382-tagging

In a social network, a user might have tags that are called skills, interests, sports, and more. There is no real way to differentiate between tags and so an implementation of this type is not possible with acts as taggable on steroids.
Enter Acts as Taggable On. Rather than tying functionality to a specific keyword (namely tags), acts as taggable on allows you to specify an arbitrary number of tag "contexts" that can be used locally or in combination in the same way steroids was used.

apartment

Github: https://github.com/influitive/apartment
Documentation: http://rubydoc.info/gems/apartment/0.24.3/frames
Railscast: http://railscasts.com/episodes/389-multitenancy-with-postgresql?view=comments

Apartment provides tools to help you deal with multiple tenants in your Rails application. If you need to have certain data sequestered based on account or company, but still allow some data to exist in a common tenant, Apartment can help.

paper_trail

Github: https://github.com/airblade/paper_trail
Documentation: http://rubydoc.info/gems/papertrail/0.9.9/frames
Railscast: http://railscasts.com/episodes/415-upgrading-to-rails-4?view=asciicast

Command-line client for Papertrail hosted log management service. Tails and searches app server logs and system syslog. Supports Boolean search and works with grep and pipe output (Unix).

carrierwave

Github: https://github.com/carrierwaveuploader/carrierwave
Documentation: http://carrierwave.rubyforge.org/rdoc/
Railscast: http://railscasts.com/episodes/253-carrierwave-file-uploads

CarrierWave makes it easy and clean to add file uploads to your application. It supports a variety of ORMs, frameworks and image processors.