Rails 6.1 has a "strict loading" Show archive.org snapshot mode that forces the developer to preload any association they plan to use. Associations no longer load lazily. An error is raised when reading an association that was not preloaded.

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Enabling strict loading is a tool to prevent n+1 queries Show archive.org snapshot .

Strict loading can be enabled for individual records, for a single association, for an entire model, or globally for all models.

See the linked article Show archive.org snapshot for details.