Address already in use – bind(2) for “127.0.0.1” port 3000 (Errno::EADDRINUSE) | Check what process is running in your localhost

I was trying to create a new rails app and got this error:

Address already in use – bind(2) for “127.0.0.1” port 3000 (Errno::EADDRINUSE)

To fix it I first check which process used my port 3000:

And I got this output:

So now I can stopped it using its pid:

I checked again if something was running in my port 3000 and I didn’t get any output so I run my rails s command and everything worked fine!

Rails with JavaScript – Recipe Manager

So… Starting with my project!

In first place, I want to build the JSON API using the Active Model Serializers gem. I add to my Gemfile:

  • gem ‘active_model_serializers’, that¬†allows you to generate your JSON in an object-oriented and convention-driven manner.

How the JSON API works?

The user makes a request, clicking a link, filling a form… where we had added an event listener. That info is serialized, translated to JSON, and submitted via an AJAX POST or GET request. With that response or data we create a new JS object and then we append the info of that object that we want to show to the DOM using a jQuery selector.

Building a JSON API consists basically in creating the response with the right data to a request and the Active Model Serializers gem is the perfect tool for this. It allows us to format our JSON, select only the information we want, as well as get access to our relationships with a single request.

Setting up the Serializer files

One of the requirements for this project is render at least one index page and one show page via JS and an Active Model Serialization JSON Backend. I was thinking in rendering my recipes index and my recipes show pages.

At the moment¬† I am displaying a list with all the recipes and links to their show page. I am not displaying more info than the title of the recipe in this page, so that’s what I want.

First I add to my Gemfile and bundle install:

  • gem ‘active_model_serializers’

Then I create my serializer file for my recipes. I tipe in my terminal:

rails g serializer recipe

And after creating it I specify which info, attributes and info of its relations I would like to have, in this case, the id and the name of the recipe.

If we specify in our contoller to “render :json” and because I have installed Serializer, Rails will now look to this folder before rendering a resource. Every object we pass to “render :json” in our controllers needs a corresponding serializer file.

* If you want deep nesting by default, you can set a configuration property in an active_model_serializer initializer. (stack overflow)

Create the file: app/config/initializers/active_model_serializer.rb with the following content:

I am going to create my serializers and specify which info I want.

Configuring the Controller to respond to JSON requests.

This is my new index action in the recipes controller:

Uhhm…I just realize that I have a problem. I want different info depending on where the object is rendered. For the index page I only want the title and the id of the recipe but for the show page I want all the info.

Lets make some changes and create two different serializers for recipes.

At the end I created these serializers:

  • category_serializer.rb
  • comment_serializer.rb
  • full_recipe_serializer.rb
  • ingredient_serializer.rb
  • rating_serializer.rb
  • recipe_ingredient_serializer.rb
  • simple_recipe_serializer.rb
  • user_recipe_serializer.rb

A lot of serializers…. I started playing with my app and encounter this error when I was trying to get one of the recipes of my index:

I think that this error is due to the info that the function fetch() is getting is not JSON.
My solution was in the serializers, I wasn’t displaying correctly the info and the relations between the objects. When I was trying to create my JS recipe object my function didn’t have the necessary info. It didn’t have the info for the has_many relations, so when I was trying to create these objects like the comments or the ingredients for the recipe I got this error.
I realize too that I didn’t need a serializer for my user class doing some methods inside the serializers where I wanted that info, for example in the comment serializer I added a method to display the name of the user who create that comment. This is better too in terms of security. I am not displaying my users data.¬†Better not to have the associations because it will give access to the whole user object, including the authenticity token.¬†
This is how my serializers look now:
Two different serializers for a recipe and I have created some methods to get the info I needed and delete the belongs_to relations. I kept the has_many relations trying to avoid defining methods for relations as much as possible, because it’s not clean, neither maintainable¬†but didn’t do it in the case of the user info.

.

I have my serializers and the following images are my changes in my controllers to respond to JSON requests:

Comments controller:

Recipes controller:

Next steps are creating my event listener and JavaScript Object Models.

Creating my files for the JS code

I first add to my Gemfile:¬†gem ‘sprockets-rails’, :require => ‘sprockets/railtie’,¬†a Ruby library for compiling and serving web assets.

I continue adding a new file for all my JS:¬†app/assets/javascripts/main.js. I don’t have to require this directive(main.js) in my manifest (application.js) because this manifest has //= require_tree, which will include all JS files in the same folder that application.js is located.

I’ll have to load the manifest file in my layout, so in the file: app/views/layouts/application.html.erb, inside the head tag, I write:

<%= javascript_include_tag “application” %>
javascript_include_tag is a Rails helper that generates a script tag instructing the browser to load that JS file.

Using arrow syntax of ES6

It differs with the normal JS function by the treatment of this. A normal JS function gets a thisaccording to the calling context (traditional semantics), but the arrow functions keep the this of the context of definition.

Creating a comment with Ajax.

In my comments/new.html.erb I have a form to create a comment. What I want to do is set it up so that I use this form, but use jQuery and AJAX to submit it, so I can handle a JSON response and display the newly created comment without redirecting to the comment show page.

Web users like fast websites and AJAX (Asynchronous JavaScript and XML) is a good technique to keep users engaged. In AJAX we first deliver a page using HTML and CSS and then use JS to add more to the DOM.

Ajax relies on several technologies: promises, XMLHttpRequestObjects, a serialization format called JSON, asynchronous Input / Output and the event loop.

Browsers and servers are only able to pass strings of text to each other. By using JSON, we can structure this text in a way that a browser or server can read as a regular JS object.

I will use the JavaScript fetch() function to apply the AJAX technique.

First step is to set up a document ready in order to detect when our HTML page has loaded, and the document is ready to be manipulated.

Then we hook up an event handler to the form’s submit event, and then block the form from doing an HTML submit. We add¬†an event listener for $(‘div#new_comment’).on(‘submit’, function(event) {} to our document¬†ready().

I am using the jQuery on() method. The on() method attaches one or more event handlers for the selected elements and child elements.

To display error message I read this tutorial.

To create the comment via Ajax I need  a JavaScript Object Model too. I added two prototype functions.

This JMO allows me to get all of the attributes of a comment into javascript by passing the comment resource sent by the controller in response to the AJAX request for json and assigning its properties to a new javascript model object. We can then use the properties of this new javascript model object within my methods on the prototype to help me display the content to the page.

After creating this event listener I follow similar procedure to create another one to handle the comments when they are created in a nested resource, and after that one to get, not post, an index of recipes and show a recipe plus a JS Object model for Recipe, RecipeIngredient, Category and Rating.

Link to my repository.

Rails Portfolio Project – Recipe Manager

Recipe Manager was built using Ruby on Rails framework and Bootstrap. All users can safely signup, login and logout. I created authentication and authorization methods without using any gem. Recipe Manager include a third party signup/login via Github thanks to the OmniAuth gem.

Users can check the recipes, rate and comment them but only admin users can create and edit the recipes and the categories. The user can browse recipes by name and author and all the comments by author and recipe. The app include reasonable validations for its forms and an ActiveRecord scope method to get the newest recipe that can be seen in its own URL, in this case: http://localhost:3000/newest_recipe.

My models:

User

  • Has many recipes
  • Has many comments
  • Has many ratings
  • Attributes: name, email, password_digest, admin, and finally I added uid and provider for the signup/login with OmniAuth.

Recipe:

  • Belongs to a user
  • Has many recipe_ingredients
  • Has many ingredients through recipe_ingredients
  • Has many recipe_categories
  • Has many categories through recipe_categories
  • Has many comments
  • Has many ratings
  • Attributes: name, cooking_time, servings, directions, date created

Ingredient

  • Has many recipe_ingredients
  • Has many recipes through recipe_ingredients
  • Attributes: name

RecipeIngredient

  • Belongs to recipe
  • Belongs to ingredient
  • Attributes: quantity.

Category

  • Has many recipe_categories
  • Has many recipes through recipe_categories
  • Attributes: name

RecipeCategory

  • Belongs to Recipe
  • Belongs to Category

Comment

  • Belongs to user
  • Belongs to recipe
  • Attributes: content

Rating

  • Belongs to user
  • Belongs to recipe
  • Attributes: score

Generate my new application:

Generate my models with their associations and create my db:

*Adding :default => true to boolean in existing Rails column

Implementing a sign-in, login and logout functionality:

In order to encrypt the passwords I will use the gem bcrypt, include “has_secure_password” in my User model and have a password_digest attribute in my users table.

Sign in with Github

  • Add to your gemfile the OmniAuth gem and the provider-specific OmniAuth gem, in this case “omniauth-github”, and run bundle install.
  • Create a file named config/initializers/omniauth.rb. I will contain the following:
  • Create an application in Github.

[Settings/Developer Settings/OAuth Apps/Register a new OAuth application]

In homepage url enter: https://localhost:3000/

In the Authorization url: http://localhost:3000/auth/github/callback

After creating the app you get a client ID and a Client secret.

  • Add dotenv-rails to your Gemfile and run bundle install.
  • Create a file named .env at the root of the application and add your Github credentials.

  • Add .env to your .gitignore file.
  • Create a link to login via Github
  • The User model needs these attributes, all strings: name, email and uid, that it is the user’s ID on Github. *I added a provider attribute later on.
  • Create the route where Github will redirect users in the callback phase of the login process.
  • And in our Sessions controller we find or create the user who logging via github.
  • In our User model:

I want to add some helpful links:

Sinatra Portfolio Project

I would like to make a Content Management System for my daughter’s nursery. They keep the daily information about the children in notebooks full of very easy to lose post its and hope this app can help with it. The daily information will be referred to as activities.

The app provides a database and web interface for users to:
* Sign up, log in or log out securely as a nursery staff or parent.
* Nursery staff can create, read, update, and delete (CRUD) an activity.
* Parents can read only the personal profile page of their children.
* User inputs are validated.
I am using Sinatra to build the app, extended with Rake for working with a SQL database using ActiveRecord ORM.
Sinatra is a Domain Specific Language implemented in Ruby that’s used for writing web applications.
My first steps to create the app are:

-Create a repository in Github.

-The project structure following the MVC conventions.

-Set my environment and my config.ru. I am following the Modular Sinatra Pattern and having a¬†config.ru¬†file is one convention of it. The purpose of config.ru is to detail to Rack (Sinatra gem is built on top of Rack) the environment requirements of the application and start the application, mount my application controllers. Rack is a convention, or specification, that lets web applications “plug” into a common interface for handling HTTP requests. To actually serve requests, we need a¬†web server¬†‚ÄĒ something that can translate HTTP requests into Ruby calls. My gem ‘thin’ is a web server that do this job.

-Create my Gemfile with all gems that I am going to run trough Bundle, which is set up in my environment file.

Here are the gems I want to use:

Sinatra: to create my web application.
activerecord: it is my Object Relation Mapper, links my Ruby models with rows in my database table. It is a gem to have access to the database mapping and associations.

sinatra-activerecord: it gives me access to some Rake tasks.
rake: short for “ruby make”, it is a package that lets me quickly create files and folders, and automate tasks such as database creation.
require_all: for a simplier way to load code.

sqlite3: sqlite is a library that implements a SQL database engine. sqlite is my database adapter gem.

thin: it is a web server.

shotgun: this is my development server.
pry: my debugger.
bcrypt: it is a hashing algorithm for passwords.
tux: it gives me an interactive console that pre-loads my database and
ActiveRecord Associations.
rake: great gem to create actions and tasks, for example a pry console to test the models and the database. It needs a Rakefile in the root directory of the app with the environment specified and requiring¬†‚Äėsinatra/activerecord/rake‚Äô.
Model classes

I think that I will need at least 3 models, User, Activity and Student.

1. User: stores user attributes, including:
* Username
* Email
* Password (Secured with Bcrypt hashing algorithm)
* Nursery_staff, a boolean value to indicate if a user is a nursery staff
2. Activity: stores activity attributes, including:
* Date
* User_id, to associate Activity to User
* Student_id, to associate Activity to Student
* Breakfast
* Morning Snacks
* Lunch
* Afternoon Snacks
* Sleep
* Nappies
* Comments
3. Student: stores student attributes, including:
* Name
* User_id, to associate Student to User
* Key person
* Room
Model Associations
User has many students and has many activities
Student has many activities and belongs to a User (parent).
Activity belongs to a Student and belongs to User.

Is it works?

I am using Visual Studio Code and after creating the structure of my project with very basic info I tried to run shotgun and was getting the following error:

I had a server running in the background. After trying a lot of different things I could stopped it with the following I found in StackOverflow:

Ran lsof -i :9393 (9393 is the port I ran it on).

I killed the process using kill -9 *pid*. My pid was: 58152.

When I ran lsof -i :9393 again, nothing showed up.

I then ran shotgun and everything works fine now.

Model Validations
You can find all info about validations here.
I will use in my controllers the methods save and update, which trigger validations for themselves and will save the object to the database only if the object is valid.
I will use some helpers to validate that some specified attributes are not empty. I want to make sure that a user gives an username and an email and that an activity has a date and a student has a name at least. I will validate the uniqueness of the email too.

 

 

 

 

 

 

Authentication system

Enable sessions in your AppController and use the gem¬†bcrypt.¬†Make sure¬†your user model¬†has_secure_password and that on your users table you store the password like password_digest“.

 

 

 

 

Protecting the session secret by Martin Fowler:

I changed my configuration to look like this:

 

 

 

 

The password fails safe to a secure hex value if SESSION_SECRET is unset.

Database

Create a Database folder (db), run your migrations to create your tables. I have created one table for the students, another table for my users and a last one for the activities.

I run:

rake db:create_migration NAME=create_students

rake db:create_migration NAME=create_users

rake db:create_migration NAME=create_activities

Then modify my migration tables according to my needs.

And finally run rake db:migrate, and all your tables will be added.

Play with my models and the database.

I run tux in my console but I got the following error

config.ru does not support require_relative so I changed my link and everything works fine!

Now it is time to be more creative and design my routes in the controllers and my views. I am using Bootstrap.

To check this project follow the link.

My way

I’m still a long way from finishing my bootcamp at Flatiron, nowadays I’m working in the Sinatra section, but I have started to think about my life after it and how successfully I can get all the necessary skills to become a competent web developer.

Completing the course is a very good first step but I think I should work  in other aspects too.

I outlined a scheme in my OneNote with the following sections in which I would like to work:

My motivations

I wrote down my motivations so I can check them out when I need it. I felt a little bit down this week because it was hard to me to understand all the connections and how the routes work with Rack, Sinatra, ActiveRecord… It was very confusing at the beginning and I felt overwhelmed thinking that I was losing a lot of time in a lab and that at this path I would never finish my course. It was very handy to read again all my motivations and get a more positive view.

My motivations are:

  • Become a Software Engineer at a tech or not tech company that I like
  • Support my family financially
  • The joy of learning and growing
  • Help other people with my code or my monetary income

Readings

I believe that as a future web developer I should start creating my personal library. It seems to me an excellent practice to complete what I learned in the bootcamp reading books.
These are my books:

  • Coding with JavaScript for Dummies
  • Eloquent JavaScript
  • Static Site Generators
  • Metaprogramming Ruby 2: Program Like the Ruby Pros (Facets of Ruby).¬† This is the book that I am reading at the moment.

Hackathons / MeetUps

I have not yet gone to any of them but I want to do it soon and overcome my fear of ridicule. I think that I still do not know enough but I’m missing out on a great learning opportunity.
I’ve already started looking for MeetUps in my city about Ruby or women programmers.

Building a resume

It would be great to fill my resume with internships and side projects before starting with my job hunt.

I already made a few projects that don’t belong to the Flatiron curriculum like a static web page and a Solitaire Game using Javascript.

Coding interviews

I would like to study some structures and algorithms to pass coding interviews.

I can get some help from:

  • Books like¬†Cracking the Coding Interview
  • Websites to practice with exercises like
  • Or other websites with general info like

Job hunt

It is too early to start with this but I keep in mind that I would like to use Flatiron services as other recruiters and my Google Fu! Maybe my networking in Hackathons can help me too!

Local web server and Visual Studio Code

I am using Visual Studio Code to follow the HTML fundamentals lessons of Flatiron Bootcamp.

In order to get a running local web server to see my code in action I chose to use the following procedure which is valid for MAC or PC and I saw in this website: Visual Studio Code and local web server.

  • Create folder for your project and add an index.html file and a package.json file to it. Inside package.json file copy/paste the following text:

I tried that but it didn’t work, I was getting an error¬† (to see more about it check this link)¬†:
String does not match the pattern of "^(?:@[a-z0-9-~][a-z0-9-._~]*/)?[a-z0-9-~][a-z0-9-._~]*$".
So I changed the string ‘Demo’ to ‘demo’ and all good.

ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

    • Get the latest version of Node running:

brew update

    • Install node running:

brew install node

    • Test that you got Node running:

node -v

    • Test that you got NPM running:

npm -v

  • Install the web server running:

npm install

This will install lite-server (defined in package.json), a static server that loads index.html in your default browser and auto refreshes it when application files change.

  • Start the local web server running:

npm start

Done!!

CLI Project Review day

Today is my CLI project review and I reserved my day to review for the last time my code and check that everything is working in my interface.

As soon as I opened the web page that I am scraping I noticed that they have changed their content. Glup! I checked to see if my code was still working….and…not, that new exhibition was not included in my list of exhibitions.

PANIC! I am nervous because is my first project review and I really don’t know how is going to be. And¬† now I found that some exhibitions were not included and‚Ķ Oh! Wait, I found out that that web page has links to more pages. I should scrape those pages too to get a full list of the exhibitions and I don’t have much time.

I started to make all the changes to get everything working well. I was inspecting the page but I din’t see why my CSS selector was not working. It seems that only the recommended exhibitions are listed, when I wanted all of them. I tried like 20 different selectors and I can not get that new exhibition! I struggle with CSS selectors‚Ķ I find them very difficult!

After 4 hours and with a mental speech to explain why my code is not working properly and I didn’t do anything to fix it I found out that I was looking to a different web page. I was looking to the archive page and not to the “whats on” page, the one I wanted‚Ķ

OK, everything is fine after all!

But I want to share this experience. I have learnt a few new things like  how to get attribute info with a CSS selector in a Nokogiri document.

 

 

And finally I have learnt another important lesson like, when you are nervous and you don’t have much time left, don’t change your code. Don’t break everything in the last minute like I did. Keep calm and later explain what you have found and try to fix it, but not in a rush. Go for a walk, breath some fresh air and take it easy. Chocolate cookies help too.