Add type for srv.on('error') and fix srv.send overload (#9)

CHANGELOG.md

@@ -6,7 +6,13 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/).
 
 ## Version 0.2.0 - tbd
 
-### Changed
+### Added
+
+- Type for special error listener `srv.on('error')`
+
+### Fixed
+
+- `srv.send` overload to also allow optional headers
 
 
 ## Version 0.1.0 - 2023-12-13

apis/services.d.ts

@@ -171,7 +171,7 @@ export class Service extends QueryAPI {
     <T = any>(details: { event: types.event; data?: object; headers?: object }): Promise<T>
     <T = any>(details: { query: ConstructedQuery; data?: object; headers?: object }): Promise<T>
     <T = any>(details: { method: types.eventName; path: string; data?: object; headers?: object }): Promise<T>
-    <T = any>(details: { event: types.eventName; entity: LinkedDefinition | string; data?: object; params?: object }): Promise<T>
+    <T = any>(details: { event: types.eventName; entity: LinkedDefinition | string; data?: object; params?: object; headers?: object }): Promise<T>
   }
 
   /**
@@ -216,6 +216,7 @@ export class Service extends QueryAPI {
   on<F extends CdsFunction>(unboundAction: F, handler: ActionEventHandler<F['__parameters'], void | Error | F['__returns']>): this
   on(eve: types.event, entity: types.target, handler: OnEventHandler): this
   on(eve: types.event, handler: OnEventHandler): this
+  on(eve: 'error', handler: OnErrorHandler): this
 
 
   // onSucceeded (eve: types.Events, entity: types.Target, handler: types.EventHandler): this
@@ -290,6 +291,10 @@ interface OnEventHandler {
   (req: Request, next: Function): Promise<any> | any | void
 }
 
+interface OnErrorHandler {
+  (err: Error, req: Request): any | void
+}
+
 // `Partial` wraps any type and allows all properties to be undefined
 // in addition to their actual type.
 // This is important in the context of CRUD events, where

test/typescript/apis/project/cds-services.ts

@@ -103,6 +103,7 @@ await srv.emit({ event: 'UPDATE', data: {} })
 await srv.send({ event: 'AuthorCreated', data: {}, headers: {} })
 await srv.send({ event: 'feeEstimation', entity: networkGroups, data: {name:'Volta'}})
 await srv.send({ event: 'feeEstimation', entity: networkGroups, data: {name:'Volta'}, params: {my: 7,new: 8}})
+await srv.send({ event: 'feeEstimation', entity: networkGroups, data: {name:'Volta'}, params: {my: 7,new: 8}, headers: {accept: 'application/json'}})
 
 // single args
 await srv.send('CREATE', 'Books', {}, {})
@@ -180,6 +181,11 @@ srv.on('CREATE', Books, (req, next) => {
   next()
 })
 
+// special error handler
+srv.on('error', (err, req) => {
+  err.message
+  req.event
+})
 
 // Typed bound/ unbound actions
 // The handler must return a number to be in line with action's signature (or void)