Ecto Patterns for Phoenix/Elixir Ecto is the data layer for Phoenix applications: schemas, changesets, queries, migrations, and transactions. Good Ecto practice keeps domain logic in contexts, enforces constraints in the database, and uses transactions for multi-step workflows. Schemas and Changesets Guidelines - Keep casting/validation in changesets; keep business logic in contexts. - Always pair validation with DB constraints ( , ). - Use for updates; avoid mass assigning without casting. Migrations Safe migration tips - Prefer additive changes: add columns nullable, backfill, then enforce…