Overview

In this exercise you will write migrations to add, remove and alter columns in the database.

Skills needed

Command line:

rake db:migrate
rake db:rollback
rails g migration AddXXXToYYY
rails g migration RemoveXXXToYYY
rails g migration NNN

Migrations:

add_column :table, :column, :type, :options
remove_column :table, :column, :type, :options
change_column :table, :column, :new_type, :options
rename_column :table, :column, :new_name

Setup

Whenever you receive a new rails project there are a few steps you probably want to perform. Can you think what those might be?

bundle install
rake db:setup #or rake db:create db:schema:load

commit these to memory!

This exercise is broken into several pieces on different branches. You'll be asked to create various migrations for each exercise and you'll be given tests to help you verify your work.

After you complete an exercise, you'll commit and then change branches. (your changes on branch A won't show up on branch B) Make sure you have NO changed files BEFORE changing branches. You can use git status to check.

Since the database is different on each branch you'll need to set it up again. You can do rake db:drop db:setup to get the database setup again.

Here's a list of those steps one more time:

Make sure you have no unstaged commits git status
Checkout the branch: `git checkout 1_ingredients_table
rake db:drop db:create db:migrate
Complete the exercise and run tests rspec spec/models/FILENAME
If successful, commit and move on.

If when running tests you ever encounter an ActiveRecord::PendingMigrationError that means you generated a new migration - but haven't run it yet.

Running tests

Each exercise comes with an rspec test. To run it:

> rspec spec/models/FILENAME

Exercises

Exercise 1: Add ingredients table

branch: 1_ingredients_table
spec: ingredient_spec.rb

Please add a new table for ingredients. Start on the 1_ingredients_table branch

It should have the following columns and types:

name - string
quantity - float
brand - string

Once you're done run the spec file: bundle exec rspec spec/models/ingredients_spec.rb

Hopefully you see something like:

Ingredient
  should have db column named name
  should have db column named quantity
  should have db column named brand
  should have db column named name of type string
  should have db column named quantity of type float
  should have db column named brand of type string

Finished in 0.01286 seconds (files took 1.57 seconds to load)
6 examples, 0 failures

If you see errors: first read them - maybe you can solve this. If not:

rollback the migration rake db:rollback
either edit the migration file itself OR delete it and generate a new one
migrate again
run the tests again

If the tests pass, you're done. Move onto the next exercise.

Exercise 2: Add authors table

branch: 2_authors_table
spec: authors_spec.rb

Now I'd like you to add a new table to store authors in. It should have the following columns:

authors

name - string
age - integer
address - string
email - string
bio - text

Run the test file spec/models/authors_spec.rb

Exercise 2b: no address

branch: same
spec: author_2b_no_address_spec.rb

Sorry, I changed my mind. We don't really need the author's address. Email is enough.

Please write a migration to remove it.

You can test your change with spec/models/author_2b_no_address_spec.rb

Exercise 2c: oops!

branch: same
spec: author_2c_no_age_spec.rb

Oops, we shouldn't track age like that! Age is a value we can calculate if we have the birthdate. Let's track birthdate's instead.

We'll do this in two steps (2c and 2d). First create a migration to remove the age field.

Test this with spec/models/author_2c_no_age_spec.rb

By the way! If you were to run spec/models/author_spec.rb right now - how many errors would you see? Why?

Exercise 2d: add birthdate

branch: same
spec: author_2d_birthdate_spec.rb

Now create another migration to add the new date.

birthdate - date

You can test this with spec/models/authors_2d_birthdate_spec.rb

Exercise 3: Use only one migration

branch: 3_modify_users_address
spec: user_spec.rb

Start on the 3_modify_users_address branch.

In the previous exercise you used two separate migrations to modify one table. In this exercise your goal is to use only 1 migration to make all the changes.

Take a look at the current users table. It currently has:

name - string
phone - integer
address - string

We want to split address up into its constituent parts. But this time do the entire change in one migration.

Rename address to street_address
Add state, zip, country and street_address2.
Change the type of phone from integer to string

A good name for this migration might be AddAddressDetailsToUsers

Bonus Exercise 4: Add column constraints

branch: 4_constraints (don't start on 3!)
spec: user_spec.rb

This time we'll make a different change set to the users table.

Please make the name field REQUIRED (null: false)
Also add a boolean admin field with a default of false.

You can do this in 1 migration, but since these are sort of different tasks 2 is also OK.

sfnewzgirl / guest-repo-1