Retrieve All Model Objects of Specified Type from Database

Task

Retrieve all the records from a model database table and load those data into model objects.

Reset and reseed database:

rails db:migrate:reset && rails db:seed

Launch Rails console:

rails console

Retrieve all Person objects from database:

all_people = Person.all

SQL command SELECT "people".* FROM "people" retrieves all rows and columns from people table.
all_people now references Relation (like array) of Person objects.

Iterate through array of Person objects, printing each’s first_name:

all_people.each do |current_person|
  puts current_person.first_name
end

Retrieve all Person objects, sorted first by last_name, then by first_name:

all_people_sorted = Person.order(:last_name, :first_name)

SQL SELECT with arguments ORDER BY "people"."last_name" ASC, "people"."first_name" ASC runs.
all_people now references sorted Relation of Person objects.

Iterate through sorted array of Person objects, printing each’s last_name and first_name:

all_people_sorted.each do |current_person|
  puts current_person.last_name + ", " + current_person.first_name
end

Exit Rails console:

exit