# Fat Controller

> A defect in which controllers hold validation, business rules, persistence and response formatting.

Record: `architecture:fat-controller`
Kind: anti-pattern
Layer: [Enforcement Core](https://banes-lab.com/records/layer/enforcement-core.md)
Severity: discouraged
Scope: correctness_verification, security_governance, control_coordination
Canonical: https://banes-lab.com/ontology#architecture-fat-controller

Listed in [Architecture principles](https://banes-lab.com/api/records/architecture.md), after [Transaction Script Sprawl](https://banes-lab.com/records/architecture/transaction-script-sprawl.md) and before [Repository Dump](https://banes-lab.com/records/architecture/repository-dump.md).

## Repair

- Refactored by: extract_use_case, move_domain_logic, add_request_mapper, add_application_service
- Detected by: controller_method_too_large, repository_calls_plus_business_rules, domain_logic_in_route_handler
- Violated by: Put validation, business rules, persistence orchestration, mapping, authorization, and response formatting in the controller layer.
- Measured by: controller method size, repository calls from controllers
- Enforced by: layer rules that keep domain logic out of controllers, size limits

## Severity

- [discouraged](https://banes-lab.com/records/vocabulary/severity-discouraged.md)

## Category

- [Anti-patterns](https://banes-lab.com/records/architecture-category/anti-patterns.md)

## Force

- [Control coordination](https://banes-lab.com/records/force/control-coordination.md)
- [Correctness verification](https://banes-lab.com/records/force/correctness-verification.md)
- [Security governance](https://banes-lab.com/records/force/security-governance.md)

## Negated by

- [Domain Service](https://banes-lab.com/records/architecture/domain-service.md)

## Linked from

- [Anti-patterns](https://banes-lab.com/ontology/principles/architecture-category-anti-patterns.md)
- [Domain Architecture](https://banes-lab.com/ontology/principles/architecture-category-domain-architecture.md)
- [Severity levels](https://banes-lab.com/ontology/schema/the-vocabulary-severity.md)
- [The forces](https://banes-lab.com/ontology/schema/the-forces.md)