Discover Method handlers and meta

package.json

@@ -23,7 +23,7 @@
     "typescript": "^3.2.4"
   },
   "scripts": {
-    "publish": "lerna run tsc && lerna publish",
+    "publish:lerna": "lerna run build && lerna publish",
     "build": "lerna run build",
     "clean": "rimraf packages/**/lib",
     "test": "jest"

packages/common/src/discovery/discovery.interfaces.ts

@@ -0,0 +1,20 @@
+import { Injectable } from '@nestjs/common/interfaces';
+import { InstanceWrapper } from '@nestjs/core/injector/container';
+
+export interface MethodMeta<T> {
+  meta: T;
+  handler: Function;
+  methodName: string;
+  provider: Injectable;
+}
+
+export interface ProviderMeta<T> {
+  meta: T;
+  provider: InstanceWrapper<Injectable>;
+}
+
+export type MetaKey = string | number | Symbol;
+
+export type ProviderFilter = (
+  injectableWrapper: InstanceWrapper<Injectable>
+) => boolean;

packages/common/src/discovery/discovery.service.ts

@@ -4,12 +4,7 @@ import { InstanceWrapper } from '@nestjs/core/injector/container';
 import { ModulesContainer } from '@nestjs/core/injector/modules-container';
 import { MetadataScanner } from '@nestjs/core/metadata-scanner';
 import { flatMap } from 'lodash';
-
-export type MetaKey = string | number | Symbol;
-
-type ProviderFilter = (
-  injectableWrapper: InstanceWrapper<NestInjectable>
-) => boolean;
+import { MetaKey, MethodMeta, ProviderFilter } from './discovery.interfaces';
 
 type HandlerFilter = (
   injectable: NestInjectable,
@@ -57,23 +52,25 @@ export class DiscoveryService {
   }
 
   /**
-   * Discovers all the handlers that exist on providers in a Nest App that match a filter
+   * Discovers all the handlers that exist on providers in a Nest App that contain metadata under a specific key
    * @param providerFilter
    * @param handlerFilter
    */
-  discoverHandlers(
+  discoverHandlersWithMeta<T>(
     providerFilter: ProviderFilter,
-    handlerFilter: HandlerFilter
-  ) {
+    metaKey: MetaKey
+  ): MethodMeta<T>[] {
     const providers = this.discoverProviders(providerFilter);
 
     return flatMap(providers, provider => {
       const { instance } = provider;
       const prototype = Object.getPrototypeOf(instance);
 
-      return this.metadataScanner.scanFromPrototype(instance, prototype, name =>
-        handlerFilter(instance, prototype, name)
-      );
+      return this.metadataScanner
+        .scanFromPrototype(instance, prototype, name =>
+          extractMeta<T>(metaKey, instance, prototype, name)
+        )
+        .filter(x => !!x.meta);
     });
   }
 
@@ -83,3 +80,20 @@ export class DiscoveryService {
     );
   }
 }
+
+function extractMeta<T>(
+  metaKey: MetaKey,
+  provider: NestInjectable,
+  prototype: any,
+  methodName: string
+): MethodMeta<T> {
+  const handler: Function = prototype[methodName];
+  const meta: T = Reflect.getMetadata(metaKey, handler);
+
+  return {
+    meta,
+    handler,
+    provider,
+    methodName
+  };
+}

packages/common/src/discovery/discovery.spec.ts

@@ -1,7 +1,6 @@
 import { Injectable, Module, ReflectMetadata } from '@nestjs/common';
 import { Test, TestingModule } from '@nestjs/testing';
 import { DiscoveryModule, DiscoveryService, providerWithMetaKey } from '.';
-import { handlerWithMetaKey } from './discovery.service';
 
 const ExampleClassSymbol = Symbol('ExampleClassSymbol');
 
@@ -16,8 +15,8 @@ const ExampleMethodDecorator = (config: any) => (target, key, descriptor) =>
 @Injectable()
 @ExampleClassDecorator('class')
 class ExampleService {
-  @ExampleMethodDecorator('method')
-  method() {}
+  @ExampleMethodDecorator('example method meta')
+  specialMethod() {}
 
   anotherMethod() {}
 }
@@ -38,25 +37,36 @@ describe('Discovery', () => {
     await app.init();
   });
 
-  it('should discover providers based on metadata', () => {
+  it('should discover providers based on a metadata key', () => {
     const discoveryService = app.get<DiscoveryService>(DiscoveryService);
 
-    const testProviders = discoveryService.discoverProviders(
+    const providers = discoveryService.discoverProviders(
       providerWithMetaKey(ExampleClassSymbol)
     );
 
-    expect(testProviders).toHaveLength(1);
-    console.log(testProviders[0].instance);
+    expect(providers).toHaveLength(1);
+    const [provider] = providers;
+    expect(provider.metatype).toBe(ExampleService);
+    expect(provider.instance).toBeInstanceOf(ExampleService);
   });
 
-  it('should discover method handlers based on a predicate', () => {
+  it('should discover method handler meta based on a metadata key', () => {
     const discoveryService = app.get<DiscoveryService>(DiscoveryService);
 
-    const handlers = discoveryService.discoverHandlers(
+    const handlerMeta = discoveryService.discoverHandlersWithMeta(
       injectable => true,
-      handlerWithMetaKey(ExampleMethodSymbol)
+      ExampleMethodSymbol
     );
 
-    console.log(handlers);
+    expect(handlerMeta.length).toBe(1);
+
+    const meta = handlerMeta[0];
+
+    expect(meta).toMatchObject({
+      meta: 'example method meta',
+      methodName: 'specialMethod'
+    });
+
+    expect(meta.provider).toBeInstanceOf(ExampleService);
   });
 });

packages/common/src/discovery/index.ts

@@ -1,2 +1,3 @@
+export * from './discovery.interfaces';
 export * from './discovery.module';
 export * from './discovery.service';

tsconfig.json

@@ -4,6 +4,8 @@
     "declaration": true,
     "noImplicitAny": false,
     "removeComments": false,
+    "strict": true,
+    "strictNullChecks": true,
     "noLib": false,
     "emitDecoratorMetadata": true,
     "experimentalDecorators": true,