We'll begin by creating the migration, as that's the foundation that will allow us to build and complete the rest of the code. Let's create a new migration as follows:
$ mix ecto.gen.migration add_user_id_to_polls* creating priv/repo/migrations* creating priv/repo/migrations/20171030030840_add_user_id_to_polls.exs
We'll need to do two things here: add the user ID column (which is a reference to the user's table) and create an index on user_id, shown as follows:
defmodule Vocial.Repo.Migrations.AddUserIdToPolls do use Ecto.Migration def change do alter table(:polls) do add :user_id, references(:users) end create index(:polls, [:user_id]) endend
Running the migration after this should result in no error messages, as shown ...