Merge pull request #3320 from abpframework/feature/type-safe-track-by-deep

Type-safe byDeep method in TrackByService

npm/ng-packs/package.json

@@ -83,6 +83,7 @@
     "snq": "^1.0.3",
     "symlink-manager": "^1.4.2",
     "ts-node": "~7.0.0",
+    "ts-toolbelt": "^6.3.6",
     "tsickle": "^0.37.0",
     "tslint": "~5.20.0",
     "typescript": "~3.5.3",

npm/ng-packs/packages/core/src/lib/services/track-by.service.ts

@@ -1,18 +1,17 @@
 import { Injectable, TrackByFunction } from '@angular/core';
+import { O } from 'ts-toolbelt';
+
+export const trackBy = <T = any>(key: keyof T): TrackByFunction<T> => (_, item) => item[key];
+
+export const trackByDeep = <T = any>(
+  ...keys: T extends object ? O.Paths<T> : never
+): TrackByFunction<T> => (_, item) => keys.reduce((acc, key) => acc[key], item);
 
 @Injectable({
   providedIn: 'root',
 })
 export class TrackByService<ItemType = any> {
-  by<T = ItemType>(key: keyof T): TrackByFunction<T> {
+  by = trackBy;
-    return ({}, item) => item[key];
-  }
-
-  byDeep<T = ItemType>(...keys: (string | number)[]): TrackByFunction<T> {
-    return ({}, item) => keys.reduce((acc, key) => acc[key], item);
-  }
 
-  bySelf<T = ItemType>(): TrackByFunction<T> {
+  byDeep = trackByDeep;
-    return ({}, item) => item;
-  }
 }

npm/ng-packs/packages/core/src/lib/tests/track-by.service.spec.ts

@@ -11,23 +11,11 @@ describe('TrackByService', () => {
 
   describe('#byDeep', () => {
     it('should return a function which tracks a deeply-nested property', () => {
-      expect(
+      const obj = {
-        service.byDeep(
+        a: { b: { c: { x: 1036 } } },
-          'a',
+      };
-          'b',
-          'c',
-          1,
-          'x',
-        )(284, {
-          a: { b: { c: [{ x: 1035 }, { x: 1036 }, { x: 1037 }] } },
-        }),
-      ).toBe(1036);
-    });
-  });
 
-  describe('#bySelf', () => {
+      expect(service.byDeep<typeof obj>('a', 'b', 'c', 'x')(284, obj)).toBe(1036);
-    it('should return a function which tracks the item', () => {
-      expect(service.bySelf()(284, 'X')).toBe('X');
     });
   });
 });

npm/ng-packs/yarn.lock

@@ -11685,6 +11685,11 @@ ts-node@~7.0.0:
     source-map-support "^0.5.6"
     yn "^2.0.0"
 
+ts-toolbelt@^6.3.6:
+  version "6.3.6"
+  resolved "https://registry.yarnpkg.com/ts-toolbelt/-/ts-toolbelt-6.3.6.tgz#2bde29106c013ed520c32f30e1248daf8fd4f5f9"
+  integrity sha512-eVzym+LyQodOCfyVyQDQ6FGYbO2Xf9Nc4dGLRKlKSUpAs+8qQWHG+grDiA3ciEuNPNZ0qJnNIYkdqBW1rCWuUA==
+
 tsickle@^0.37.0:
   version "0.37.1"
   resolved "https://registry.yarnpkg.com/tsickle/-/tsickle-0.37.1.tgz#2f8a87c1b15766e866457bd06fb6c0e0d84eed09"