feat(core) add more utility reflector methods

Author: kamilmysliwiec

packages/core/services/reflector.service.ts

@@ -1,4 +1,5 @@
 import { Type } from '@nestjs/common';
+import { isObject } from '@nestjs/common/utils/shared.utils';
 
 /**
  * Helper class providing Nest reflection capabilities.
@@ -32,12 +33,55 @@ export class Reflector {
    * @param targets context (decorated objects) to retrieve metadata from
    *
    */
-  public getAll<TResult extends any[] = any, TKey = any>(
+  public getAll<TResult extends any[] = any[], TKey = any>(
     metadataKey: TKey,
     targets: (Type<any> | Function)[],
   ): TResult {
     return (targets || []).map(target =>
       Reflect.getMetadata(metadataKey, target),
     ) as TResult;
   }
+
+  /**
+   * Retrieve metadata for a specified key for a specified set of targets and concat results.
+   *
+   * @param metadataKey lookup key for metadata to retrieve
+   * @param targets context (decorated objects) to retrieve metadata from
+   *
+   */
+  public getAllAndConcat<TResult extends any[] = any[], TKey = any>(
+    metadataKey: TKey,
+    targets: (Type<any> | Function)[],
+  ): TResult {
+    const metadataCollection = this.getAll(metadataKey, targets);
+    return metadataCollection.reduce((a, b) => {
+      if (Array.isArray(a)) {
+        return a.concat(b);
+      }
+      if (isObject(a) && isObject(b)) {
+        return {
+          ...a,
+          ...b,
+        };
+      }
+      return b;
+    });
+  }
+
+  /**
+   * Retrieve metadata for a specified key for a specified set of targets and return a first not undefined value.
+   *
+   * @param metadataKey lookup key for metadata to retrieve
+   * @param targets context (decorated objects) to retrieve metadata from
+   *
+   */
+  public getAllAndOverride<TResult = any, TKey = any>(
+    metadataKey: TKey,
+    targets: (Type<any> | Function)[],
+  ): TResult {
+    const metadataCollection = this.getAll(metadataKey, targets).filter(
+      item => item !== undefined,
+    );
+    return metadataCollection[0];
+  }
 }

packages/core/test/services/reflector.service.spec.ts

@@ -15,6 +15,7 @@ describe('Reflector', () => {
       expect(reflector.get(key, Test)).to.eql(value);
     });
   });
+
   describe('getAll', () => {
     it('should reflect metadata of all targets', () => {
       const key = 'key';
@@ -23,4 +24,25 @@ describe('Reflector', () => {
       expect(reflector.getAll(key, [Test])).to.eql([value]);
     });
   });
+
+  describe('getAllAndConcat', () => {
+    it('should reflect metadata of all targets and concat arrays', () => {
+      const key = 'key';
+      const value = 'value';
+      Reflect.defineMetadata(key, value, Test);
+      expect(reflector.getAllAndConcat(key, [Test, Test])).to.eql([
+        value,
+        value,
+      ]);
+    });
+  });
+
+  describe('getAllAndOverride', () => {
+    it('should reflect metadata of all targets and return a first not undefined value', () => {
+      const key = 'key';
+      const value = 'value';
+      Reflect.defineMetadata(key, value, Test);
+      expect(reflector.getAllAndOverride(key, [Test, Test])).to.eql(value);
+    });
+  });
 });