I am building out a musician social site. Users can create bands, and they are considered from then on the manager of the band. I want to refer to a bands instance of a user as the manager.

Despite specifying the relationship in the models, and specifying class_name: "User" and foreign_key: "manager", the app will not save a new Band to the database.

user.rb

class User < ApplicationRecord

    has_many :bands, foreign_key: 'manager'



    validates_presence_of :name

    validates_presence_of :password_digest

    validates_presence_of :username

    validates_uniqueness_of :username



    has_secure_password



    def admin?

        self.role == "admin"

    end

end

band.rb

class Band < ApplicationRecord

    belongs_to :manager, class_name: 'User', foreign_key: 'manager'

    validates_presence_of :name

    validates_uniqueness_of :name

    validates_presence_of :description

end

schema.rb

ActiveRecord::Schema.define(version: 2018_12_27_040935) do



    create_table "bands", force: :cascade do |t|

        t.string "name"

        t.text "description"

        t.integer "manager_id"

        t.datetime "created_at", null: false

        t.datetime "updated_at", null: false

        t.index ["manager_id"], name: "index_bands_on_manager_id"

    end



    create_table "users", force: :cascade do |t|

        t.string "name"

        t.string "username"

        t.string "password_digest"

        t.datetime "created_at", null: false

        t.datetime "updated_at", null: false

        t.string "role", default: "user"

    end



end

seeds.rb

Edited seeds.rb

User.destroy_all

Band.destroy_all



user = User.new(name: 'John')

user.save

user = User.find_by_name('John')



user_band = user.bands.new(name: 'Band #1', description: 'My first band')



if user_band.save

    puts "Done"

else

    puts "Incomplete"

end

I run rails db:seed, and expect to see 'Done' in the console.
I get 'Incomplete'.

Testing in the rails console, the band instance has the error of "Manager must exist"

Also, a single user instance exists, with and id of 1.

Update associations as follows:

band.rb

belongs_to :manager, class_name: 'User', foreign_key: 'manager_id'

user.rb

has_many :bands, foreign_key: 'manager_id'

Before creating band, manager should be present in user table.

manager = User.find(1)

band = manager.bands.new(name: "Jams", description: "Hey, its our first band.") 

if band.save

   puts "Done"

else

   puts "Incomplete"

end

band.rb

belongs_to :manager, class_name: 'User', foreign_key: 'manager_id'

user.rb

has_many :bands, foreign_key: 'manager_id'

To test try this:

manager = User.create(...user_information)

jms = Band.new(name: "Jams", description: "Hey, its our first band.")

jms.manager = manager

jms.save

If it fails, what is the output of jms.errors?

Okay, so I changed my migration file, which apparently was causing the issue. The schema.rb looks identical, but the seeds.rb is now this…

models

user.rb
has_many :bands, foreign_key: 'manager_id'

band.rb
belongs_to :manager, class_name: 'User', foreign_key: 'manager_id'

seeds.rb

User.destroy_all

Band.destroy_all



user = User.new(name: 'John', username: "johnny", password: "nice")

user.save

user = User.find_by_name('John')



user_band = Band.new(name: 'Band #1', description: 'My first band', manager_id: user.id)



if user_band.save

    puts "Done"

else

    puts "Incomplete"

end

The errors were: ActiveRecord::StatementInvalid: SQLite3::SQLException: no such table: main.managers: INSERT INTO "bands" ("name", "description", "manager_id", "created_at", "updated_at") VALUES (?, ?, ?, ?, ?)

Changed migration file for bands

Previously

create_table :bands do |t|

    t.belongs_to :manager, foreign_key: true

    t.string :name

    t.text :description

    t.timestamps

end

Changed To

create_table :bands do |t|

    t.belongs_to :manager

    t.string :name

    t.text :description

    t.timestamps

end

Removed option , foreign_key: true, Dropped DB, ran migrations, and now.

It Works…