kratos-biz-layer

<essential_principles>

How Kratos Business Layer Works

Clean Architecture Dependency Rule

The business layer (biz) is the core of Clean Architecture in Kratos microservices:

Dependency Flow: Service → Biz → Data

• Biz defines interfaces that data layer implements
• Biz contains business logic independent of frameworks
• Biz uses domain models not ORM entities

Three Key Components

1. Business Models (internal/biz/models.go)

• Domain entities with validation tags
• Independent of database structure
• Use validator struct tags for validation

2. Repository Interfaces (internal/biz/interfaces.go)

• Define data access contracts
• Implemented by data layer
• Accept/return business models, not ORM entities

3. Use Cases (internal/biz/{entity}.go)

• Orchestrate business logic
• Depend on repository interfaces
• Handle validation, logging, error mapping

Wire Dependency Injection

All constructors must be added to ProviderSet in internal/biz/biz.go:

var ProviderSet = wire.NewSet(NewSymbolValidator, NewSymbolUseCase)

After changes, run make generate to regenerate Wire code. </essential_principles>

1. Create a new entity (use case + interface + model + validator)
2. Add methods to existing use case
3. Create standalone validator
4. View examples and patterns

Wait for response before proceeding.

After reading the workflow, follow it exactly.

<reference_index> All domain knowledge in references/:

Core Patterns: use-case-pattern.md, interface-pattern.md, model-pattern.md Code Style: naming-conventions.md

Additional patterns (error handling, logging, transactions, testing) are covered within use-case-pattern.md. </reference_index>

<workflows_index>

<success_criteria> Business layer code is correct when:

• Use case struct has repo, log, validator, tm fields
• Constructor function returns interface type (not struct)
• Methods accept context.Context as first parameter
• Validation happens before repository calls
• Errors are properly wrapped and logged
• Repository interface added to interfaces.go
• Business model added to models.go with validation tags
• Constructor added to ProviderSet in biz.go
• User reminded to run make generate </success_criteria>