Duplicate column name 'id' when the scope already selects columns

[mbillard]

If the scope already selects columns:

@items = Item.select('`items`.*')

Then calling the cache on the scope directly will raise an error:

cache [@items] do
  ...

The error:

Mysql2::Error: Duplicate column name 'id': SELECT CONCAT(`id`, '-', `updated_at`) FROM (SELECT  `items`.*, items.id, items.updated_at FROM ...

[mbillard]

A workaround is to explicitly load the relation before calling the cache:

@items.load
cache [@items] do
  ...