Error in your foreign key creations instructions page.

https://loopback.io/doc/en/lb4/todo-list-tutorial-sqldb.html#specify-the-foreign-key-constraints-in-todo-model
In your example below.

@model({
  settings: {
    foreignKeys: {
      fk_todo_todoListId: {
        name: 'fk_todo_todoListId',
        entity: 'TodoList',
        entityKey: 'id',
        foreignKey: 'todoListId',
      },
    },
  },
})
export class Todo extends Entity {
  //etc.
}

When following the setup above to run database migration for my local postgresdb as part of todo example tutorial, I encountered the following error:

Cannot migrate database schema error: column "todoListId" referenced in foreign key constraint does not exist
    at Parser.parseErrorMessage (/Users/andywongcheeming/Projects/poc/todo-list/node_modules/pg-protocol/dist/parser.js:283:98)

I was left puzzled why the instructions did not work as expected. I dig up online and my personal ChatGPT to understand if Postgres DB has case-sensitive when comes to table and field naming conventions. It turns out that it does.

When I go back and check my local postgres todo definitions via psql cli.

todo_db=# \d todo
                  Table "public.todo"
   Column   |  Type   | Collation | Nullable | Default
------------+---------+-----------+----------+---------
 id         | integer |           | not null |
 title      | text    |           | not null |
 desc       | text    |           |          |
 iscomplete | boolean |           |          |
 todolistid | integer |           |          |

It turns our the foreign key todolistid comes out as lower case by default when running Loopback db migration tool. The sample @model code above supplied as {foreignKey: 'todoListId'}.

I corrected it to use lower-case, dropped the database and started the migration all over again. The migration works this time.

Thus, I must ask - shouldn't the instructions be updated to use lowercase since the plugin creates tables and field names in lowercase by default?

Inizia dalla sezione sulle chiavi esterne collegata nel tutorial sul database SQL dell’elenco Todo di LoopBack e confronta il relativo valore foreignKey con lo schema PostgreSQL prodotto dalla migrazione. Aggiorna l’esempio in modo che il vincolo documentato corrisponda al nome della colonna generata, quindi verifica che l’esempio Todo venga migrato correttamente su PostgreSQL.