Polymorphic association in rails?

rubyonrails-docs
1

Hi All,

Please provide idea or best practice link for polymorphic association step by step example.

Please explain with an compelete example.

Thanks

Learning rails 6 .

2

the docs on this are actually a great reference and provide some examples that are really helpful

1 Like
3

I would like to know how to execute query on polymorphic association model.

i have Human, Company, Address, model.

Run command for Address model as :

rails g model Address h_number:string city:string country:string disst:string addressable:references{polymorphic}

class Human < ApplicationRecord
  belongs_to :company
  has_one :address, as: :addressable
end

class Company < ApplicationRecord
  has_many :humen
  has_one :address, as: :addressable
end

class Address < ApplicationRecord
  belongs_to :addressable, polymorphic: true
end

schema

irb(main):036:0> Address
=> Address(id: integer, h_number: string, city: string, country: string, disst: string, addressable_type: string, addressable_id: integer, created_at: datetime, updated_at: datetime)

irb(main):037:0> Human
=> Human(id: integer, first_name: string, last_name: string, sal: integer, age: integer, company_name: string, company_id: integer, created_at: datetime, updated_at: datetime)

irb(main):038:0> Company
=> Company(id: integer, name: string, year: integer, emp: integer, head: string, value: integer, created_at: datetime, updated_at: datetime)

insert data

Company.create(name: "jain inc", year: 1994, emp: 15000, head: "bharat", value: 900000)

Human.create(first_name: "learning", last_name: "rails", sal: 70000, age:28, company_name: "jain inc", company_id: 1)

When i am execute query h = Human.first.address it is not getting address of comapny and human.

gettting nil :

Human Load (0.8ms)  SELECT "humen".* FROM "humen" ORDER BY "humen"."id" ASC LIMIT $1  [["LIMIT", 1]]
  Address Load (0.7ms)  SELECT "addresses".* FROM "addresses" WHERE "addresses"."addressable_id" = $1 AND "addresses"."addressable_type" = $2 LIMIT $3  [["addressable_id", 1], ["addressable_type", "Human"], ["LIMIT", 1]]
=> nil

Please any idea how to get Address of Company and Human. One more thing i am a bit confuse about addressable, polymorphic association is it class or module or concern?

Thanks

learning rails 6 .

4

please any idea for this ?

5

Spelling error. Not sure if this is the whole problem

6

this is fine, because it accept plural

7

Have you created Address records corresponding to the Human or Company you are looking for ?

For your example, an Address with those attributes : ["addressable_id", 1], ["addressable_type", "Human"]

8

no, can you explain?

how should I do this?

9 
Address.create!(
  addressable_type: 'Human', 
  addressable_id: 1, 
  city: 'my city'
)

Then you can retrieve it with h = Human.first.address

10

this is fine.

thank you