MatijaL
Hi guys,
I’m trying to build something similar to Twitter where users can follow other users. I’m not sure exactly how to properly create self-referencing schema in this case.
Migrations:
defmodule MyApp.Repo.Migrations.CreateUsers do
use Ecto.Migration
def change do
create table(:users) do
add :username, :string
end
end
end
defmodule MyApp.Repo.Migrations.CreateFollows do
use Ecto.Migration
def change do
create table(:followings) do
add :follower_id, references(:users, on_delete: :delete_all)
add :followed_id, references(:users, on_delete: :delete_all)
timestamps()
end
create index(:followings, [:follower_id, :followed_id], unique: true)
end
end
Schemas:
defmodule MyApp.User do
use Ecto.Schema
schema "users" do
field :username, :string
...
end
end
defmodule MyApp.Follow do
use Ecto.Schema
schema "followings" do
---
end
end
Can someone help me write the schemas properly using many_to_many please?
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tfwright
Did you try following this example in the docs? Basically it’s just a normal schema that you pass to the
join_throughoption ofmany_to_manyinstead of the table name directly. Although it’s maybe worth noting that you don’t need to use a join schema. Personally I often prefer to avoid dealing with non-intuitive concept names like a “Follow”…MatijaL
I did check those pages abut I’m not entirely sure which approach even to take as it’s the self-referencing schema.
tfwright
What part of the self-referencing is causing you problems?
MatijaL
To be honest, I don’t even know… I also don’t like those abstract names, what do you think about a table called “followings” with “user_id” and a “follower_id”?