Rails Create method Validation Error with one to one association - ruby-on-rails

Question

I have been learning ruby on rails from Coursera and am specifically at the one to one to one association module. I was trying to emulate the one to one association example in the tutorial on my own system however i get the ActiveRecord::RecordInvalid error. This is what i have done to reach this point:
1) rails g model person first_name last_name
2) rake db:migrate
3) rails g model personal_info height:float weight:float person references
4) rake db:migrate
5) Migration 20160725143537_create_people.rb has the following code:
class CreatePeople < ActiveRecord::Migration[5.0]
def change
create_table :people do |t|
t.string :first_name
t.integer :age
t.string :last_name
t.timestamps
end
end
end
6) Migration 20160727184247_create_personal_infos.rb has the following code:-
class CreatePersonalInfos < ActiveRecord::Migration[5.0]
def change
create_table :personal_infos do |t|
t.float :height
t.float :weight
t.references :person, foreign_key: true
t.timestamps null: false
end
end
end
7) The code in person.rb is as follows:
class Person < ApplicationRecord
has_one :personal_info
end
8) The code in personal_info.rb is as follows:-
class PersonalInfo < ApplicationRecord
belongs_to :person
end
9) The code in seeds.rb is as follows:-
Person.destroy_all
Person.create! [
{first_name: "Kalman", last_name: "Smith", age: 33, login: "kman", pass: "abc123"},
{first_name: "John", last_name: "Whatever", age: 27, login: "john1", pass: "123abc"},
{first_name: "Michael", last_name: "Smith", age: 15, login: "mike", pass: "not_telling"},
{first_name: "Josh", last_name: "Oreck", age: 57, login: "josh", pass: "password1"},
{first_name: "John", last_name: "Smith", age: 27, login: "john2", pass: "no_idea"},
{first_name: "Bill", last_name: "Gates", age: 75, login: "bill", pass: "windows3.1"},
{first_name: "LeBron", last_name: "James", age: 30, login: "bron", pass: "need more rings"},]
10) Now i go to the rails console (rails c) and type the following:
pi1 = PersonalInfo.create!(height:6.2, weight:220.0). This is when i get the aforementioned error which looks like this:
irb(main):002:0> pi1 = PersonalInfo.create!(height:6.2, weight:220.0)
(0.0ms) begin transaction
(0.0ms) rollback transaction
ActiveRecord::RecordInvalid: Validation failed: Person must exist
from C:/RailsInstaller/Ruby2.2.0/lib/ruby/gems/2.2.0/gems/activerecord-5.0.0/lib/active_record/validations.rb:78:in `raise_validation_error'
from C:/RailsInstaller/Ruby2.2.0/lib/ruby/gems/2.2.0/gems/activerecord-5.0.0/lib/active_record/validations.rb:50:in `save!'
from C:/RailsInstaller/Ruby2.2.0/lib/ruby/gems/2.2.0/gems/activerecord-5.0.0/lib/active_record/attribute_methods/dirty.rb:30:in `save!'
from C:/RailsInstaller/Ruby2.2.0/lib/ruby/gems/2.2.0/gems/activerecord-5.0.0/lib/active_record/transactions.rb:324:in `block in save!'
from C:/RailsInstaller/Ruby2.2.0/lib/ruby/gems/2.2.0/gems/activerecord-5.0.0/lib/active_record/transactions.rb:395:in `block in with_transaction_returning_status'
from C:/RailsInstaller/Ruby2.2.0/lib/ruby/gems/2.2.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/abstract/database_statements.rb:232:in `block in transaction'
from C:/RailsInstaller/Ruby2.2.0/lib/ruby/gems/2.2.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/abstract/transaction.rb:189:in `within_new_transaction'
from C:/RailsInstaller/Ruby2.2.0/lib/ruby/gems/2.2.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/abstract/database_statements.rb:232:in `transaction'
from C:/RailsInstaller/Ruby2.2.0/lib/ruby/gems/2.2.0/gems/activerecord-5.0.0/lib/active_record/transactions.rb:211:in `transaction'
from C:/RailsInstaller/Ruby2.2.0/lib/ruby/gems/2.2.0/gems/activerecord-5.0.0/lib/active_record/transactions.rb:392:in `with_transaction_returning_status'
from C:/RailsInstaller/Ruby2.2.0/lib/ruby/gems/2.2.0/gems/activerecord-5.0.0/lib/active_record/transactions.rb:324:in `save!'
from C:/RailsInstaller/Ruby2.2.0/lib/ruby/gems/2.2.0/gems/activerecord-5.0.0/lib/active_record/suppressor.rb:45:in `save!'
from C:/RailsInstaller/Ruby2.2.0/lib/ruby/gems/2.2.0/gems/activerecord-5.0.0/lib/active_record/persistence.rb:51:in `create!'
from (irb):2
from C:/RailsInstaller/Ruby2.2.0/lib/ruby/gems/2.2.0/gems/railties-5.0.0/lib/rails/commands/console.rb:65:in `start'
from C:/RailsInstaller/Ruby2.2.0/lib/ruby/gems/2.2.0/gems/railties-5.0.0/lib/rails/commands/console_helper.rb:9:in `start'
from C:/RailsInstaller/Ruby2.2.0/lib/ruby/gems/2.2.0/gems/railties-5.0.0/lib/rails/commands/commands_tasks.rb:78:in `console'
from C:/RailsInstaller/Ruby2.2.0/lib/ruby/gems/2.2.0/gems/railties-5.0.0/lib/rails/commands/commands_tasks.rb:49:in `run_command!'
from C:/RailsInstaller/Ruby2.2.0/lib/ruby/gems/2.2.0/gems/railties-5.0.0/lib/rails/commands.rb:18:in `<top (required)>'
from bin/rails:4:in `require'
from bin/rails:4:in `<main>'irb(main):003:0>
I am using rails 5.
I would really appreciate you guys helping me in resolving this error. Thanks in advance

Answer 1

As per your requirement you have defined has_one association between Person and PersonalInfo.
The best way to create PersonalInfo first you should create Person then PersonalInfo such as:
#person = Person.create!(first_name: "Kalman", last_name: "Smith", age: 33, login: "kman", pass: "abc123")
Now you can create PersonalInfo
#person.personal_info.create(height:6.2, weight:220.0)
I think it would help you. Still if you have any concern please let me know.

Answer 2

You'll need to set a person_id:
PersonalInfo.create!(person_id: 1, height:6.2, weight:220.0)

Answer 3

As you can see in your CreatePersonalInfos migration, the person reference has a foreign key constraint. This means you won't be able to create PersonalInfo without an associated Person. You can either create it by providing a valid person_id
PersonalInfo.create!(height:6.2, weight:220.0, person_id:1)
or through the association on Person
#person.create_personal_info(height:6.2, weight:220.0)
You can also remove the foreign_key option in your migration to remove the DB-level constraint.