Data Model + Migration

Scope

Use this skill when introducing or modifying persisted data.

Checklist

• Generate migrations via mix ecto.gen.migration and update priv/repo/migrations/*.
• Define schemas in lib/app/model with use App, :model, explicit field types, and timestamps.
• Validate with App.Validate helpers and App.Field types (e.g. Field.TrimmedString).
• Avoid casting programmatically-set fields; set them explicitly on the struct when creating records.
• Use Ecto.Changeset.get_field/2 to read changeset values (no access syntax).
• Preload associations before rendering in templates.
• Add or update fixtures in test/support/fixtures when tests need new data.