Rails 4 Migration | Add Table with Reference - ruby-on-rails

Question

I am attempting to create a Collaboration table in my Rails 4 project, but I've run into an issue. I wish it to belong_to a single user, the collaborator.
I ran the following command to generate the model and the migration, which I've also copied below.
rails generate model Collaboration project:references collaborator:references accepted:boolean
Migration:
class CreateCollaborations < ActiveRecord::Migration
def change
create_table :collaborations do |t|
t.references :project, index: true, foreign_key: true
t.references :collaborator, index: true, foreign_key: true
t.boolean :accepted
t.timestamps null: false
end
end
end
Model:
class Collaboration < ActiveRecord::Base
belongs_to :project
belongs_to :collaborator, class_name: 'User'
end
I updated the Collaboration model to include , class_name: 'User' as shown above. Similarly, I updated the existing Strategy model to include a has_many :collaborations
class Project < ActiveRecord::Base
has_many :collaborations
end
When I run rake db:migrate, I get the following error reported.
rake aborted!
StandardError: An error has occurred, this and all later migrations canceled:
PG::UndefinedTable: ERROR: relation "collaborators" does not exist
I'm a bit puzzled as to wy this is happening. Any assistance would be greatly appreciated! Thank you. :)
EDIT:
Adding code for my User model as well.
class User < ActiveRecord::Base
authenticates_with_sorcery!
has_many :projects
has_many :collaborations
end
I edited out validations for fields such as password, email, etc to try to remove clutter.

Answer 1

This part of your migration:
t.references :collaborator, index: true, foreign_key: true
will try to create a foreign key inside the database so that the collaborator_id column of the collaborations table will be guaranteed to be NULL or contain the id of a column in the collaborators table. You can't create that FK until the collaborators table exists.
The error you're getting is:
relation "collaborators" does not exist
and that's just telling you that you don't have a collaborators table but you're trying to reference it.
You need a migration to create the collaborators table before you create your collaborations table.

Answer 2

In Rails 5, at least, you can use foreign_key: {to_table: ... }} as follows.
create_table :messages, id: :uuid do |t|
t.references :from_user, type: :uuid, index: true, null: false, foreign_key: {to_table: :users, on_delete: :cascade}
t.references :to_user, type: :uuid, references: :user, index: true, null: false, foreign_key: {to_table: :users, on_delete: :cascade}
t.text :body, null: false
t.timestamps
end

Answer 3

sorry for being late, but essentially it's all about convenience, remember that's the essence of rails. so; every reference should be targeting the table that should be in the plural (since a table holds many "objects") therefore, you must make the reference to plural so rails will generate a reference to a singular object. button line, your migration should look more like;
class CreateCollaborations < ActiveRecord::Migration
def change
create_table :collaborations do |t|
t.references :projects, index: true, foreign_key: true
t.references :collaborators, index: true, foreign_key: true
t.boolean :accepted
t.timestamps null: false
end
end
end
Now, if you follow the conventions, then you should have no problem with the rest, just keep in mind that belong_to is to a singular object and has_many is to a plural object.
PS: I would not use past reference for the column, like accepted
Happy Coding