# Repositories And Data Access

> Implement repository interfaces for data persistence and abstraction over database operations using Bun ORM. Use when this capability is needed.

- Skill: `tomevault-io/repositories-and-data-access` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add tomevault-io/repositories-and-data-access`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/repositories-and-data-access/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: tomevault-io (https://skillmd.com/u/tomevault-io)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/tomevault-io/repositories-and-data-access

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# Repositories & Data Access

## When to use this skill

- Create data access layer abstractions for entities
- Implement Bun-based repositories for database operations
- Define repository interfaces that services depend on
- Add transaction support (WithTx) to repositories

## Key principles

1. **Interface segregation**: One repository interface per domain model
2. **Bun ORM**: Use Bun for type-safe database operations
3. **Transaction support**: Every repository implements `WithTx(tx bun.IDB)`
4. **Context-aware**: All operations accept `context.Context`
5. **No business logic**: Repositories only handle CRUD; logic lives in services

## Pattern

Repositories are data access only:

- Define interface with CRUD operations (Create, GetByID, Update, Delete)
- Implement with Bun in `bun_*.go` files
- Accept `bun.IDB` at construction (not concrete `*bun.DB`)
- Return interfaces from constructors
- Missing records return `nil, nil` for single queries; empty slice for batch queries

## Example

See [examples/bun_todo_repository.go](examples/bun_todo_repository.go) for:

- ITodoRepository interface definition
- bunTodoRepository Bun implementation
- CRUD and batch query patterns

## Common mistakes

1. Returning errors for missing records (use nil instead)
2. Forgetting `WithTx()` method
3. Putting business logic in repositories
4. Not passing context to Scan/Exec
5. Repository-to-repository calls instead of service orchestration

## References

- [internal/repositories/interfaces.go](../../../internal/repositories/interfaces.go) - Core repository interfaces
- [internal/repositories/bun_user_repository.go](../../../internal/repositories/bun_user_repository.go)
- [internal/repositories/bun_account_repository.go](../../../internal/repositories/bun_account_repository.go)

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> Source: [Authula/authula](https://github.com/Authula/authula) — distributed by [TomeVault](https://tomevault.io).
<!-- tomevault:4.0:skill_md:2026-06-17 -->