--- name: kratos-service-layer description: Generates gRPC\/HTTP service handlers for go-kratos microservices. Creates service structs, handler methods, and integrates with protobuf definitions. Use when implementing RPC handlers, adding API endpoints, creating dual transport (HTTP\/gRPC) handlers, or connecting transport layer to business logic in kratos services. --- ## How Kratos Service Layer Works ### Service Layer Role Connects transport (gRPC\/HTTP) to business logic: **Responsibilities**: - Handle gRPC\/HTTP requests - Map proto DTOs to business models (via mapper) - Call use case methods - Map results back to proto responses - Convert business errors to gRPC status codes ### Service Struct Pattern ```go type {Entity}Service struct { pb.Unimplemented{Entity}ServiceServer \/\/ Embed unimplemented server uc biz.{Entity}UseCase \/\/ Use case dependency } ``` ### Handler Method Pattern ```go func (s *{Entity}Service) Create{Entity}(ctx context.Context, in *pb.Request) (*pb.Response, error) { \/\/ 1. Map request to business model entity := {Entity}FromRequest(in) \/\/ 2. Call use case result, err := s.uc.Create{Entity}(ctx, entity) if err != nil { return nil, toServiceError(err) \/\/ Map business error to gRPC error } \/\/ 3. Map result to response return &pb.Response{Entity: toProto{Entity}(result)}, nil } ``` <\/essential_principles> What would you like to do? 1. Create service handlers for new entity 2. Add handler methods to existing service 3. View handler patterns and examples **Wait for response before proceeding.** <\/intake> | Response | Workflow | |----------|----------| | 1, "create", "new" | `workflows\/create-service.md` | | 2, "add", "extend" | `workflows\/add-handlers.md` | | 3, "examples", "patterns" | `workflows\/view-examples.md` | **After reading the workflow, follow it exactly.** <\/routing> **Core**: handler-pattern.md, service-structure.md, error-mapping.md **Mappers**: mapper-conventions.md <\/reference_index> | Workflow | Purpose | |----------|---------| | create-service.md | Generate service handlers and mappers | | add-handlers.md | Add methods to existing service | | view-examples.md | Show patterns | <\/workflows_index> Service layer code is correct when: - Service struct embeds Unimplemented{Entity}ServiceServer - Constructor added to service.ProviderSet - Handlers map DTOs via mapper functions - Errors converted to gRPC status codes - All methods have godoc comments - User reminded to run `make generate` <\/success_criteria>