Active Record Design Your Own

##Learning Competencies

• Use Active Record Migrations to create a database
• Use Active Record Queries to query a database

##Summary

Now that you've had a chance to implement Active Record in a couple of different defined problem spaces, it's time to take over and build from scratch on a problem space of your choice. The purpose of this exercise is to deepen your learning of Active Record and give you a sandbox to work in for the future.

The releases have suggested time boxes to keep you moving along. If you are well over the time suggested, call for help.

##Releases

###Release 0 : Choose A Problem Space and Requirements (30 min).

####Step 1: Choose a Problem Space A problem space is just a fancy way of saying choose what you want to work on and explore Active Record in. You can choose whatever you like as long as it meets these basic requirements:

• The data can be represented in a relational database with at least 3 tables and at least one many-to-many and one one-to-many relationship.
• There is data for you to use (like a csv file) or it is easy to create data using faker.
• You can write at least 5 user stories that define the requirements for your problem space. For example (You can list the senators from a state). At least 1 of these stories needs to be complex (require some calculation)
• You can succinctly define the problem space in two or three sentences.

####Step 2: Write the Requirements (User Stories) Requirements or User Stories define how we want our program to act. In this case, how we want our program to interact with the data. Write at least 5 user stories and 1 complex user story.

####Step 3: Design the Schema Use SQL Designer to design the schema that will meet these requirements.

####Step 4: Write the README.md In the ar-design-your-own directory, add your

• Problem Space description
• List of requirements
• Embedded Image of Schema Design

####Step 5: Check Off Grab a staff member, coach or (if neither of these are available, a student other than your pair) and walk through your README. Make sure you can describe what you are going to do and that your schema does in fact meet your requirements. If not, make adjustments as needed. In the last line of your README add a statement "Checked off by 'bob'".

###Release 1 : Build the Skeleton (1 hour) Up to this point, you have been building your AR challenges off of an existing skeleton. It's time for you to take ownership of this skeleton by writing on yourself. The goal of this step is to get you closer to understanding all the code in a skeleton (you may not get all of it which is ok).

####Step 1 : Use Existing Skeleton As A Guide You will be creating a skeleton that is essentially the same as the AR Skeleton skeleton. Open this and use it as a guide as you walk through the rest of these steps. DO NOT COPY AND PASTE

####Step 2: Create the Directories Inside your ar-design-your-own directory, add the following folders:

• app
• app/models
• db
• db/data (if you have external data files (like CSV))
• db/migrate
• lib
• spec

As you create each directory, discuss with your pair what will be stored here.

####Step 3: Setup Configuration Files. Many of the files in this skeleton are used to configure your application files and load external files. As you create each one, try to know why the file is important and what at least one line of code does. If you don't know all lines at this time that is ok, just type them in. ** DO NOT COPY AND PASTE **

Create these files in the root directory

• Gemfile
• Rakefile - modify to match your database file names, only add the tasks you will need.
• .gitignore
• (the .gitkeep file is empty so you don't need it yet)

Create these files in their appropriate sub folders

• db/config.rb

Remove files and references you are not using. (ex: 'legislators.csv' )

####Step 4: Up and Running Make sure your skeleton is configured well by creating the database, a migration and a model

• To create the database, run rake db:create
• To create the migration, run rake db:create_migration then edit the migration to add table and fields
• To run the migration, run rake db:migrate
• To create a model, add a file to the models folder with a model class and a link to the db/config file. Note - there are better ways to link files, but this will work for now

require_relative '../../db/config'

class YourModel < ActiveRecord::Base
# implement your YourModel model here
end

You should now be able to work with your model. To test this, run rake:console to open your application in irb. Test it out by running

• YourModel.create(creation data here)
• `YourModel.all - should list all the instances of your model.

You can also test by opening your database in sqlite3 and verifying your schema and data.

###Release 2 : Migrations (30 minutes) Create the migrations and models for all of the tables in your schema.

###Release 3 : Associations Create the associations for your models. Be sure to test these associations in rake:console and sqlite3.

###Release 4 : Validations Add at least one validation to each model. Test these validations in rake:console and sqlite3

###Release 5 : Seed the Database Create a seeds.rb file in the db directory. Add code to seed the database.

###Release 6 : Play (optional) There are a lot of ways you can experiment with this challenge. Here are a few:

• Add Rspec tests in the spec directory
• Add custom validation methods
• Create methods to query your data in various ways.

##Resources

• Validation Overview