ecto

name: ecto description: Ecto conventions for schemas, changesets, query composition, and migration design. Use when modifying schemas, context queries, constraints, indexes, transactions, or migrations.

Ecto

Rules

1. Always use changesets for insert/update operations.
2. Preload associations before template access to avoid N+1 queries.
3. Use transactions for multi-step operations that must succeed together.
4. Add database constraints and mirror them in changesets.
5. Keep Repo usage inside context modules, not web layer modules.
6. Add indexes for foreign keys and high-frequency query fields.
7. Keep migration changes reversible and explicit.

Use This Skill When

• Editing schemas, changesets, context query functions, or migrations.
• Designing table constraints and index strategy.
• Reviewing database access boundaries in contexts.

Workflow

1. Start from schema and changeset rules.
2. Add/update migration for structural changes.
3. Expose operations through context APIs.
4. Add tests for valid and invalid paths.

References

• ./references/ecto-conventions.md
• ../elixir/references/project-structure.md

Related Skills

• elixir
• testing