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Just because it has a computer in it doesn't make it programming. If there is no code in your link, it probably doesn't belong here. Direct links to. 2 Learn Ruby on Rails: Book Two Version , 1 March Daniel Kehoe ii In this book, you'll build a working web application so you'll gain hands-on Hands-on learning with actual Rails applications is the key to absorbing and. Rails 3. Cloves Carneiro Jr., and Rida Al Barazi mpanion ok Available. A beginner's guide to building web applications with Ruby on Rails.

Or do it with Unix commands: This makes it easy to collaborate with other Rails developers, providing consistency and predictability. The mailers folder is for code that sends email messages.

Rails provides a basic model—view—controller framework but it is often necessary to extend it. Use the cd.. This chapter will introduce you to software source control, also called version control or revision control.

But it makes professional software development possible and, at the core, it is essentially a form of time travel. To understand time travel, we need to understand state. We know about states of matter. Water can be ice, liquid, or steam. Imagine a machine with a button that, each time it is pressed, changes water from one state to another. We call this a state ma- chine. Almost every software program is a state machine. When a program receives an input, it transitions from one state to another.

Light or dark. Ice, liquid, or steam. Or, in a web application: We look things up, we think, we type errors and we make corrections. We want to preserve the state of our work. More importantly, it archives a snapshot of the current state in a repository where it can be retrieved if needed.

We can go back and recover the state of our work at any point where we committed a snapshot to the repository. In software development, travel to the past is essential because we often make mistakes or false starts and have to return to a point where we know things were working correctly.

What about time travel to the future? Version control systems allow us to explore alternative futures by creating a branch for our work. Git The dominant version control system among Rails developers is Git, created by the developer of the Linux operating system.

Unlike earlier version control systems, Git is ideal for wide-scale distributed open source software development. Well-written com- mit messages describe your work to co-workers or open source collaborators. That means you can customize an open source project for your own needs. Fixing bugs large or small and adding features to open source projects are how you build your reputation in the Rails community. Collaboration is easy when you use a branch in Git.

If you and a coworker are working on the same codebase, you can each make a branch before adding to the code or making changes. Git supports several kinds of merges, so you can integrate your branch with the trunk when your task is complete. All the power of Git comes at a price.

Have you noticed how time travel movies require mental gymnastics, especially when you try to make sense of alternative futures and intersecting timelines? You can build the tutorial project without using Git.

But I urge you to use Git and a GitHub account for this project, for two reasons. Before I show you Git commands, I want to mention that some people use graphical client applications to manage Git.

It will take effort to master Git; the commands are not intuitive. But it is absolutely necessary to become familiar with Git basics. Is Git Installed? If Git is not found, install Git.

See the article Rails with Git and GitHub for installation instructions. Is Git Configured?

Make sure Git knows who you are. Every time you update your Git repository with the git commit command, Git will identify you as the author of the changes. Use the same email address for Git, your GitHub account, and Heroku to avoid headaches. Extending the time traveler analogy, initializing a Git repository is equivalent to setting up the time machine. We add the Unix symbol that indicates Git should be initialized in the current directory git init dot: Initialized empty Git repository in It creates a hidden folder named.

You can peek at the contents: GitIgnore The hidden. The rails new command creates a. Take a look at the contents of the. If you find yourself ignoring temporary files generated by your text editor or operating system, you probably want to add a global ignore instead: But the story of your project would be confusing and overly detailed.

Do so now: There are three forms of the git add command: Like time travel, Git will stretch your understanding of what makes sense. Most often, you can simply use the git add -A form of the command. Now commit your project to the repository: The pristine state of your new Rails application is now recorded in the repo. Fri Dec 18 I like to use the git log command with an option for a compact listing: The commit ID is abbreviated but it is all you need to travel back in time.

A fourth stage is important when you work with others: The repositories hosted on your GitHub account establish your reputation as a Rails developer for employers and developers you may work with. Did you create a GitHub account? Now would be a good time to add your repo to GitHub.

Go to GitHub and create a new empty repository for your project. If the repository is public, hosting on GitHub is free. Add GitHub as a remote repository for your project and push your local project to GitHub. Before you copy and paste the command, notice that you need to in- sert your own GitHub account name. Now you can view your project repository on GitHub at: Take a look. GitHub is abso- lutely essential to all open source Rails development. It will be good practice for using Git.

Markdown is a popular way to add formatting to improve readability. Very cool! The git log command will display your project history: Chapter 9 Gems The art of selecting gems is at the heart of Rails development. Some gems add functionality or features to a website. Other gems play a supporting role, making development easier or implementing basic infrastructure.

Gems are open source. Gems are often created when a developer has used the same code as a component in more than one web application. He or she will take time to release the code as a gem. There is no evaluation or review process in publishing gems.

Gems are hosted on a public server, rubygems. A single command, gem push, uploads a gem to the rubygems. Over 50, gems have been released since rubygems.

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Some of these gems are used by one or two developers on their own projects. GEMS Many others have been neglected and abandoned due to lack of interest.

Only a few thousand gems are popular and widely used. There is no single authoritative source of recommendations for gems. The Ruby Toolbox website categorizes and ranks many gems by popularity, and it is a good place to begin hunting for useful gems.

How many are closed? Popular gems are likely to have many reported issues, some of which are trivial problems or feature requests. Gems that are actively maintained will have many closed issues and, ideally, only a few open issues. Regular and recent activity in the commit log indicates the gem is actively maintained. Rails Gems Rails itself is a gem that, in turn, requires a collection of other gems.

This becomes clear if you look at the summary page for Rails on the rubygems. Each of these gems has its own dependencies as well. When you install Rails, a total of 44 gems are automatically installed in your development environment.

Gems for a Rails Default Application In addition to the Rails gem and its dependencies, a handful of other gems are included in every rails new default starter application: Where Do Gems Live? Gems are handled by the Ruby interpreter no differently than your own code. Experienced programmers who have used software libraries in other languages might wonder how it works.

Ruby has a require method that allows you to import software libraries into your programs. You can run the gem env command to reveal the RubyGems environment details which are normally hidden from you: If you use RVM, gems are saved to a hidden.

A global subfolder contains the Bundler gem. It lists each gem that the developer wants to use. Bundler checks to see if the gem is already installed and only downloads gems that are needed. Bundler checks for the newest gem version and records the version number in the Gem- file. Bundler also downloads any gem dependencies and records the dependencies in the Gemfile. More importantly, when other devel- opers install your application, Bundler will automatically install all the gems including dependencies and correct versions needed to run the application.

When you deploy the application to production for others to use, automated deployment scripts such as those used by Heroku install all the required gems. Bundler provides a bundle update command when we want to replace any gems with newer versions.

If you run bundle update, any new gem ver- sions will be downloaded and installed and the Gemfile. Be aware that updating gems can break your application, so only update gems when you have time to test and resolve any issues. You can run bundle outdated to see which gems are available in newer versions. The exception is the Rails gem itself. We always specify the version of Rails we are using for de- velopment.

GEMS gem 'jquery-rails' Turbolinks makes following links in your web application faster Read more: Some version numbers may be different if a newer Rails version was released since this was written.

Rails changes frequently and newer versions may not work as we expect. This is needed for au- tomated deployment scripts such as those used by Heroku. Other gems are commented out the lines begin with the character. These are suggestions and we can ignore them or remove them. If you remove the extra clutter in the Gemfile it will look like this: I learned of these gems from a variety of different sources: We want to stick with the Foundation 5 framework, not the newer Foundation 6 framework, to avoid some potential errors.

Rails let you specify groups for development, test, or production. What version of Rails is installed in your current gemset? Check with: Change this line as needed: Install the required gems on your computer: Fetching gem metadata from https: Resolving dependencies Using rake Your bundle is complete!

You can use your text editor to view the contents of Gemfile. Run gem list to see all the gems that are loaded into the development envi- ronment: If your devel- opment environment is not set up correctly, you may see error messages when Bundler attempts to install the Nokogiri gem.

Nokogiri is often needed by other gems it is a dependency of some gems and Nokogiri can become a problem to install. Unlike most gems that are written in pure Ruby, parts of Nokogiri are written in the C language and must be compiled using system tools that vary with different operating systems.

If you get a message: GIT 85 fatal: Not a git repository or any of the parent directories: You are probably not in your project directory. Use the Unix command pwd to see where you are. To investigate, enter: Configuration Security GitHub is a good place to store and share code. But when your repos are public, they are not a good place for secret account credentials. Operating systems Linux, Mac OS X, Windows provide mechanisms to set local environment variables, as does Heroku and other deployment platforms.

With a bit of Unix savvy, you can set environment variables using the Unix shell. The article Rails Environment Variables shows alternatives to using Unix en- vironment variables, if for any reason you cannot set environment variables on your machine. The shell is the program that gives us the command line interface we see in the Terminal or console application. Unix gives you a choice of shell programs with names like sh, bash, ksh, and zsh ; each has a slightly different way to set environment variables.

The most common shell program is bash. You should see either.

The command might not be exactly the same but it is likely you will see some export com- mands. Set Environment Variables Set the following environment variables in your.

You can use Command-Shift-. The credentials are the same you use to sign in to the SendGrid website. Add your SendGrid username and password to your. Have you already created a MailChimp mailing list? Troubleshooting Check that the SendGrid user name is set in your Unix environment variables: Close and reopen your terminal to make sure the environment includes any recent changes. Most computers use the bash shell and you can set environment variables in your.

But not every system is alike. Be sure to restart your server when you modify this file. Your secret key is used for verifying the integrity of signed cookies. If you change this key, all old signed cookies will become invalid!

Make sure the secret is at least 30 characters and all random, no regular words or you'll be exposed to dictionary attacks. Make sure the secrets in this file are kept private if you're sharing your code publicly. For development, use example. If you have your own domain name, you can use that instead. Be sure to use spaces, not tabs. Make sure there is a space after each colon and before the value for each entry. Replace the following: If your password contains any of these characters you should sur- round the string with single quotes: Go to your Rails application directory and create a new secret token: You can learn more in the article Send Email with Rails.

In the early days of the Internet, an experienced system administrator could set up an SMTP server to distribute email.

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Now, because of efforts to reduce spam, it is necessary to use an established email service to ensure deliverability. In production, for high volume transactional email and improved deliverability, it is best to use a service such as SendGrid. Alternatives are: For convenience during development, some developers use their own Gmail account to send email.

After the code you just added, add the statement: Send email in development mode? Later, after we add a contact form to the tutorial application, the application will be ready to send email messages. The pages are delivered fast and no Ruby code is required. Add a Home Page Make sure you are in your project directory. Start the application server: The Rails application server looks for any pages in the public folder by default.

Since then, index. Enter the URL http: If you are using Cloud9 or Nitrous. Introducing TDD With test-driven development, a developer tests behavior before implementing a feature, expecting to see an error condition.

Then the developer implements the feature and sees a successful result to the test. Beginners tend to think TDD is scary and complicated. Real TDD means writing tests in Ruby before implementing features, but the principle is the same. But what if you want to override the default behavior? Here is where it is helpful to have two terminal sessions going in different tabs.

There is no need to restart your application server to see the new behavior. If you need to start the server: The code is buried deep in the Rails framework. However, if you know the convention and the technique for overriding it, you have both convenience and power at your disposal. Web browsers make requests. The beauty and simplicity of the World Wide Web architecture, as conceived by Tim Berners-Lee in , is that the web is nothing more than a request from a web browser and a response from a web server.

We can reduce the mystery of how the web works to its simplest components when we investigate the request-response cycle. Figure The request-response cycle. Inside the Browser We can see the actual request, and the actual response, by using the diagnostic tools built into the web browser.


Start the application server if it is not already running: Even if you prefer Mozilla Fire- fox or Apple Safari, try this in Chrome, so you can follow along with the text. Alternatively, you can clear the browser cache. Select the Network tab in the Developer Tools View.

There is only one: The request is composed of: Viewing a request in the Developer Tools View. Now try requesting the home page by entering the URL http: For that, go to the server logs or the console window.

Notice how the diagnostic messages in the console window match the headers in the browser diagnostic view. Notice there are no console log messages for pages delivered from the public folder. Document Object Model What happens after the browser receives a response from the server?

It provides a structural representation of the document. Here is a diagram that shows what happens in the server during the request- response cycle. You learned earlier that, from the perspective of a software architect, Rails is organized to conform to the model—view—controller software design pattern.

The MVC design pattern is optimal for web applications and is a central organizing principle for Rails. The MVC design pattern originated in the design of desktop applications. We can see the reason for the quibble in the next diagram. The diagram shows the MVC architecture as part of the Rails software stack.

At the base of the stack is the web browser. Despite the quibble about nomenclature, the architecture is well understood and used by all Rails developers. The controller will obtain any needed data from a model. After obtaining data, the controller will render a response combining data from the model with a view component that provides markup and layout.

The model, view, and controller classes you create will inherit behavior from parent classes that are part of the framework, so you will have less code to write yourself. In most Rails applications, a model obtains data from a database, though some models obtain data from a remote connection to another server. For example, a User model might retrieve a user name and email address from a local database. The controller can obtain data from more than one model if necessary.

A controller can have more than one action. For example, a User controller might have actions to display a list of users, or add or delete a user from a list. We use the terms action and method interchangeably when we talk about a Rails controller; to be precise, controller actions are implemented as methods.

An index view might show a list of users. In many controllers, on com- pletion, the destroy action will redirect to the index view, and create will redirect to either show or new. This conceptual overview will be easier to grasp when you actually see the code for a model, view, and controller.

You can leave it in place.

Viewing request headers in the Developer Tools View. Model—View—Controller in Rails. Model—View—Controller stack in Rails. Our goal is to build a practical web application that you can really use. We can create the routes, model, view, and controller in any order. All must exist before our web application will respond to a request for a home page.

The Name Game Much of the art of programming lies in choosing suitable names for our cre- ations. In Rails, there is often a model with the same name as a controller though a controller can use data from multiple models.

Replace the contents with this: It will be become familiar soon and you can look up the details in the reference documentation, RailsGuides: Routing from the Outside In. Model Most Rails models obtain data from a database. When you use a database, you can use the rails generate model command to create a model that inherits from the ActiveRecord class and knows how to connect to a database.

This simple class provides an easy introduction to Ruby code. Software architects call these abstrac- tions objects. In Ruby, everything we create and manipulate is an object. Ruby makes it easy for a method to return data when called; the value assigned by the last statement will be delivered when the method is called.

The variable is named on the left side of the equals sign; a value is assigned on the right side. We call the equals sign an assignment operator. Not surpris- ingly, a number also can be assigned to a variable, either a whole number an integer or a decimal fraction a float. More interestingly, any Ruby object can be assigned to a variable. We can create our own objects, as we have by creating the Owner class.

Or we can use the library of objects that are supplied with Ruby. The Rails API gives us additional classes that are useful for web applications. Learning the syntax of Ruby code gets you started with Ruby programming; knowing the API classes leads to mastery of Ruby.

It is described in the Ruby API reference documentation. The Date class has a Date. You can see this syntax when we assign Date. The Date. Imagine a September birthday. You must use Date.

1. Check for Code Smells

If you enter a date in the format Date. When the Date. The Date class can perform complex calendar arithmetic. The variables birthdate and today are instances of the Date class.

The if Then we subtract today from birthday. This shows you the power of programming in Ruby. Notice that I needed 16 paragraphs and over words to explain 15 short lines of code. But without knowing more than this, we can build a simple web application.

View The Owner model provides the data we want to see on the Home page. In a typical application, one controller can render multiple views, so we make a folder to match each controller.

Want to add to the discussion?

Or use the Unix mkdir command: Some experi- enced developers prefer to add gems that provide the Haml or Slim templating engines. As you might guess, a View that uses the Haml templating syntax would be named new. This markup allows us to insert Ruby code which will be replaced by the result of evaluating the code.

You may have noticed that we refer to the Owner model with the variable owner. It will be clear when we create the Visitors controller why we use this syntax a variable name that begins with the character is called an in- stance variable. The Rails implementation becomes useful if the name is retrieved from a database or created programmatically. There is no way to display a calculation using only static HTML, so Rails gives us a way to display the birthday countdown calculation.

Controller The Visitors controller is the glue that binds the Owner model with the Visi- torsController new view. In this context, the character is only a documentation con- vention. The class name is written in camelCase with a hump in the middle, like a camel so we can combine two words without a space. We create an instance variable named owner and assign an instance of the Owner model.

Keep in mind the purpose of the controller. Each controller action method responds to a request by obtaining a model if data is needed and rendering a view. The new method is deceptively simple.

Hidden behavior inherited from the ApplicationController does all the work of rendering the view. We can make the hidden code explicit if we wish to. It would look something like this: Rails often offers default behavior that looks like magic because the underlying implementation is hidden in the depths of the Rails code library. Revealing the hidden code, we see that invoking the new method calls a render method supplied by the ApplicationController parent class.

The code underlying the render method is complex. Rails takes care of the rest. As you gain experience, you can dive into the Rails source code to unravel the magic.

Scaffolding This tutorial aims to give you a solid foundation in basic concepts. The model— view—controller pattern is one of the most important. For example, Rails Guides: Students often use scaffolding to create simple Rails applications. Enter the command: Dynamic home page shows days until a birthday. And the underlying code conforms to the conventions and structure of Rails.

Git At this point, you might have the Rails server running in your console window. You might think you have to enter Control-c to shut down the server and get the command prompt. You can open more than one console window.

Your terminal application lets you open multiple tabs so you can easily switch between windows without using a lot of screen real estate. It is convenient to have a console window open for the server and another for various Unix commands. Before we do any more work on our tutorial application, we need to learn about troubleshooting and debugging.

Use the git status command to check: Interactive Ruby Shell There will be times when you want to try a snippet of Ruby code just to see if it works. IRB is a Ruby interpreter that runs from the command line.

It executes any Ruby code and provides an immediate response, allowing you to experiment in real-time. If you enter a valid Ruby expres- sion, the interpreter will display the result of evaluating the expression.

This method generates a new receipt object, but it doesn't actually render it to a file or do anything with it, it just stores the information in memory so that prawn.

We've got everything connected, and we are ready to go and now we need to serve it up. That means that we're going to have to go into our charges controller and actually render this PDF out.

This show action is actually where we need to be writing that code. Sometimes, when you view the show, you want the JSON response, sometimes you want the html response, but in this case, we want the PDF response. This is something that you might not have been aware of, you can do a response to a format, and you can have your format html, you can have your format.

PDF, which will detect the. This is a method that allows us to send arbitrary data back, and we'll use the type option for this to set the content type so the browser knows what we're sending back and how to interpret the data. Now, we have to pass a couple other options here.

This will be the file name that will send over, and the browser will read that and see that is the file name to save the file as. So this is a very important option to pass in. The browser may or may not be able to interpret that or make a guess at it, but you're going to want to set the type to make sure it knows, and then one often useful feature here is the disposition setting that inline, and this will allow you to set your PDF to render inside of the browser, so it's a really useful thing to do, and I'm going to format this method call like so, and this will allow it to render inside of the browser.

This will take a second to load because it's gotta generate the PDF, and then it is automatically set up for you in the browser. That's it, you already have a working PDF generation working. Garner - A set of Rack middleware and cache helpers that implement various caching strategies. IdentityCache - A blob level caching solution to plug into ActiveRecord.

Readthis - High performance, pooled, ActiveSupport compliant caching with Redis. It supports object marshalling, timeouts, single or multiple nodes, and namespaces. It also provides a time-sensitive form submission. Voight-Kampff - A Ruby gem that detects bots, spiders, crawlers and replicants. Commander - The complete solution for Ruby command-line executables.

Main - A class factory and DSL for generating command line programs real quick. Optimist - A commandline option parser for Ruby that just gets out of your way. Rake - A make-like build utility for Ruby. Slop - Simple Lightweight Option Parsing. Terrapin - A small command line library Formerly Cocaine.

Thor - A toolkit for building powerful command-line interfaces. Don't remember a command? Ask Betty. Pastel - Terminal output styling with intuitive and clean API. Ru - Ruby in your shell. Produce highly readable terminal tables, even from large, unwieldy data sets and streams. Tmuxinator - Create and manage complex tmux sessions easily. Whirly - A simple, colorful and customizable terminal spinner library for Ruby. Fog - The Ruby cloud services library. ComfortableMexicanSofa - Powerful Rails 5.

Publify - A self hosted Web publishing platform on Rails. PushType - A next generation, open source content management system for Ruby on Rails. Radiant - A no-fluff, open source content management system designed for small teams. Code Analysis and Metrics Barkeep - Barkeep is a fast, fun way to review code.

Engineering organizations can use it to keep the bar high. Brakeman - A static analysis security vulnerability scanner for Ruby on Rails applications. Cane - Code quality threshold checking as part of your build. Coverband - Rack middleware to help measure production code coverage.

Fasterer - Make your Rubies go faster with this command line tool highly inspired by fast-ruby and Sferik's talk at Baruco Conf. Flay - Flay analyzes code for structural similarities.Here is the syntax: You can bring your own project which can be as simple as completing a tutorial. The application. Make sure the secret is at least 30 characters and all random, no regular words or you'll be exposed to dictionary attacks.

With a partner, Granda Fairbook, he founded Acme Manufacturing, later acquired by the Advent Corporation, to develop his discovery for use in the Turboencabulator. In Book One, I explain the culture and practices of the Rails community.

Rails notice messages will get styled with the Foundation success class. Ruby golf is the sport of writing code that uses as few characters as possible. Each program you start in a terminal window is a separate process and multiple processes can run simultaneously. Check the status to make sure:

CONCEPCION from Davenport
See my other posts. One of my hobbies is basque rural sports. I do like sharing PDF docs violently.