Rapid Prototyping with Rails: Lesson 1

01 Oct 2014

Items covered:

Bundle Install/Bundle Exec
Creating your Rails App
Folder Directory
Rake Routes
Relational Databases

Bundle Install

Before you couldn't have multiple versions of gems installed on your machine when switching b/w projects.

Bundler creates a sandbox in your application where the proper versions of your gems are stored.

Bundle exec

does the samething and is used when your system level rake (rake db:migrate) for example is not compatible with the current settings. Therefore you have to use bundle exec rake db:migrate or just bundle exec.

Heroku also uses Bundler.

Creating your app:

Files you should always look at:

1. database.yml

Tells the application how to connect to the database *In development - we use sqlite3 *In production - we use postgres (although in this course Heroku takes care it for us)

For sqlite - your database is in your code base and its one file, unlike others where is an application and usually your database is hosted somewhere:

production
        adapter: mysql
        database: myapp_development
        host: localhost
        username:
        password:

You will want to mimick your local enviornment as much as possible to your production enviornment in order to catch bugs

2. Gemfile

3. Routes File

How the request initally get's routed. The blueprint of your application ad its capabilities.

Folder Directory

app - where you spend most time
  assets - where you put all static files, images, etc.
  controllers
  mailers - outbound mail. Not good to use because you can easily get flagged as spam
   (use a transactional email provider (stmp mailers) hosts such as mailgun, postmark, etc. )
   models
   views - where our erb goes
bin - where your executable code goes - we never touch this
application.rb - sets application defaults such as timezone, load path
enviornment folder - configurations for development and production, and testing.
                  - you can also create custom enviornments - such QA, intergration or staging
initializers folder - where you files that you want to load when your application
                    is initialized
Config folder
  locales - yml files - is a way to internationalize your app. Is comprised of comlicated hashes
        and you no longer write using strings. Extremely painful to manage files
Lib - you can also put assets in there
Tasks - you can place rake tasks in here
log - stores all terminal logs from your application
public - where you store your error pages
      - robosts - tell search engines where to go within your application
Vendor - a relic from the past
.gitignore - tells git what files to ignore when committing. (.files are hidden files)
Readme - is what is dispayed when you push your app to Github.

Rake Routes

shows all possible endpoints in your application You can also view your routes in your browser by going to localhost:3000/rails/info/routes in Rails 4 only or you can use the terminal: rake routes | grep _______

Relational Databases:

A series of spreadsheets.

To connect these tables in order to link infromation: 1. primarykey in rails is the "id" 2. foreignkey is the creation of a "userid" column with the primarykey in on other tables to connect to the main table.

There are 2 Views

Data View: very much like Excel
Schema View: lists the column name and the data type allowed for that column.

1:M

the Foreign_key is always on the many side of a one to many relationship

ORMs

ActiveRecord is an ORM (Object Relational Mapper), a pattern created by Martin Fowler which describes how to abstract data from a database into code. Prior to this, using PHP, you would write sql code directly in the views.

In console, using "= _" is equivalent to your last returned item.

Rails is good for simple, applications with quick builds that aren't for existing application is analytics.

Setting up 1:M b/w posts and users (Posts were previously created)

Create user table Terminal: rails g migration create_users
Create Users model Create model - singular, snack_case of Class name
Need to add foreign key to the many side (the Posts table) Terminal: rails g migration adduseridtoposts

Inside migration file:

def change
    add_column :table_name :foreign_key (which is normally the resource+primary_key), :datatype (always will be integer)

    add_column :posts, :user_id, :integer
  end

Write in hasmany and belongsto on the models

Virtual Attribute

attributes that are not columns, are given through associations

Mass Assignment

The ability create/update AR obj through a hash where the keys match the attirbute or virtual attribute. example:

Post.new(title: "some title", url: "some url", user = User.first)

Post.new & Post.create

Both can be used for mass assignment. Post.new is in memory (no user id assigned) while Post.create will update to the database immediately.

Post.build and Post.new are the same.

When in the console:

You can run the following commands:
  user = User.first
  post = Post.first
  post.user **** virtual attribute
  post.title
  post.user_id = user ***NO, you can only set objects to object and integers to integers
  post.user_id = user_id

grit| commit