refactor(@nestjs/microservices) extract magic strings into constants

packages/microservices/client/client-grpc.ts

@@ -8,6 +8,7 @@ import { ClientOptions } from '../interfaces/client-metadata.interface';
 import { GRPC_DEFAULT_URL } from './../constants';
 import { ClientGrpc, GrpcOptions } from './../interfaces';
 import { ClientProxy } from './client-proxy';
+import { GRPC_CANCELLED } from './constants';
 
 let grpcPackage: any = {};
 
@@ -25,7 +26,7 @@ export class ClientGrpcProxy extends ClientProxy implements ClientGrpc {
     this.grpcClient = this.createClient();
   }
 
-  public getService<T extends {}>(name: keyof T): T {
+  public getService<T extends {}>(name: string): T {
     const { options } = this.options as GrpcOptions;
     if (!this.grpcClient[name]) {
       throw new InvalidGrpcServiceException();
@@ -59,14 +60,15 @@ export class ClientGrpcProxy extends ClientProxy implements ClientGrpc {
   ): (...args) => Observable<any> {
     return (...args) => {
       return new Observable(observer => {
-        const call = client[methodName](...args);
         let isClientCanceled = false;
+        const call = client[methodName](...args);
+
         call.on('data', (data: any) => observer.next(data));
         call.on('error', (error: any) => {
-          if (error.details === 'Cancelled') {
+          if (error.details === GRPC_CANCELLED) {
             call.destroy();
-            if ( isClientCanceled ) {
-              return; // do not error if cancel was inititiated by Client
+            if (isClientCanceled) {
+              return;
             }
           }
           observer.error(error);
@@ -76,10 +78,11 @@ export class ClientGrpcProxy extends ClientProxy implements ClientGrpc {
           observer.complete();
         });
         return () => {
-          if (!call.finished) {
-            isClientCanceled = true;
-            call.cancel();
+          if (call.finished) {
+            return undefined;
           }
+          isClientCanceled = true;
+          call.cancel();
         };
       });
     };

packages/microservices/client/constants.ts

@@ -1,2 +1,3 @@
 export const ECONNREFUSED = 'ECONNREFUSED';
-export const CONN_ERR = 'CONN_ERR';
+export const CONN_ERR = 'CONN_ERR';
+export const GRPC_CANCELLED = 'Cancelled';

packages/microservices/constants.ts

@@ -10,6 +10,7 @@ export const MESSAGE_EVENT = 'message';
 export const ERROR_EVENT = 'error';
 export const CLOSE_EVENT = 'close';
 export const SUBSCRIBE = 'subscribe';
+export const CANCEL_EVENT = 'cancelled';
 
 export const PATTERN_METADATA = 'pattern';
 export const CLIENT_CONFIGURATION_METADATA = 'client';

packages/microservices/interfaces/client-grpc.interface.ts

@@ -1,3 +1,3 @@
 export interface ClientGrpc {
-  getService<T extends {}>(name: keyof T): T;
+  getService<T extends {}>(name: string): T;
 }

packages/microservices/server/server-grpc.ts

@@ -1,11 +1,11 @@
+import { fromEvent } from 'rxjs';
+import { takeUntil } from 'rxjs/operators';
 import { InvalidGrpcPackageException } from '../exceptions/invalid-grpc-package.exception';
 import { InvalidProtoDefinitionException } from '../exceptions/invalid-proto-definition.exception';
 import { GrpcOptions, MicroserviceOptions } from '../interfaces/microservice-configuration.interface';
-import { GRPC_DEFAULT_URL } from './../constants';
+import { CANCEL_EVENT, GRPC_DEFAULT_URL } from './../constants';
 import { CustomTransportStrategy } from './../interfaces';
 import { Server } from './server';
-import { fromEvent } from 'rxjs';
-import { takeUntil } from 'rxjs/operators';
 
 let grpcPackage: any = {};
 
@@ -106,7 +106,7 @@ export class ServerGrpc extends Server implements CustomTransportStrategy {
       const handler = methodHandler(call.request, call.metadata);
       const result$ = this.transformToObservable(await handler);
       await result$.pipe(
-        takeUntil(fromEvent(call, 'cancelled')),
+        takeUntil(fromEvent(call, CANCEL_EVENT)),
       ).forEach(data => call.write(data));
       call.end();
     };