An operation is a single method or function that a caller can invoke. In an HTTP API context it's often called a route or endpoint.
This framework promotes a bottom-up approach to building APIs.
The first step to implementing a new operation is to define the request and response types along with an operation function.
type Request struct { // request params } type Response struct { // response data } func Operation(ctx context.Context, req Request) (Response, error) { // operation logic }Alternatively, the operation function can be defined as a method on a struct.
type Service struct { } func (s Service) Operation(ctx context.Context, req Request) (Response, error) { // operation logic }In case of an HTTP API, the next step is to define encoding and decoding functions for request, response and errors.
func DecodeOperationRequest(ctx context.Context, r *http.Request) (Request, error) { // decode request } func EncodeOperationResponse(ctx context.Context, w http.ResponseWriter, response Response) error { // encode response } func EncodeOperationError(ctx context.Context, err error, w http.ResponseWriter) bool { // encode error // return true if the error is considered "handled", false otherwise (error gets passed to the error handler) return true }Finally, create a constructor function for the HTTP handler.
func NewOperationHandler(op operation.Operation[Request, Response], errorHandler httptransport.ErrorHandler) http.Handler { return httptransport.NewHandler( op, DecodeOperationRequest, EncodeOperationResponse, EncodeOperationError, httptransport.WithErrorHandler(errorHandler), httptransport.WithOperationName("operation"), ) }Alternatively, the constructor function can instantiate the operation itself as well.
func NewOperationHandler(errorHandler httptransport.ErrorHandler) http.Handler { return httptransport.NewHandler( NewOperation(), DecodeOperationRequest, EncodeOperationResponse, EncodeOperationError, httptransport.WithErrorHandler(errorHandler), httptransport.WithOperationName("operation"), ) }Register the HTTP handler in the router.