Updating memoize decorator

src/decorators/memoize.ts

@@ -1,8 +1,17 @@
-export function Memoize(): Function {
+export function Memoize(propsToWatch?: string[]): Function {
+    const hasPropsToWatch = typeof propsToWatch !== 'undefined' && Array.isArray(propsToWatch);
+    if (typeof propsToWatch !== 'undefined' && !hasPropsToWatch) {
+        throw new Error('Somethings wrong with the propsToWatch Array');
+    }
     return function(target: any, propertyKey: string, descriptor: PropertyDescriptor) {
         const originalMethod = descriptor.value;
         descriptor.value = function(this: any, ...args: any[]) {
-            const reflectKey = `${JSON.stringify(this)}_${JSON.stringify(args)}_${propertyKey}`;
+            let modelKeyPart = this;
+            if (hasPropsToWatch) {
+                const filteredEntries  = Object.entries(this).filter(([k,v]) => propsToWatch.includes(k))
+                modelKeyPart = Object.fromEntries(filteredEntries);
+            }
+            const reflectKey = `${JSON.stringify(modelKeyPart)}_${JSON.stringify(args)}_${propertyKey}`;
             const hasReflectData = Reflect.hasMetadata(reflectKey, target);
 
             if (hasReflectData) {

tests/decorators/memoize.spec.ts

@@ -9,8 +9,32 @@ class MemoizeTestModel extends Serde<MemoizeTestModel> {
     }
 }
 
+class MemoizeArgsTestModel extends Serde<MemoizeTestModel> {
+    name: string;
+    @Memoize() doNameRandom(t: string): string {
+        return this.name + t + (Math.random() * 10);
+    }
+}
+
+class MemoizePropsToWatchTestModel extends Serde<MemoizePropsToWatchTestModel> {
+    name: string;
+    desc: string
+    @Memoize(['name']) doNameRandom(): string {
+        return this.name + (Math.random() * 10);
+    }
+}
+
+class MemoizePropsToWatchArgsTestModel extends Serde<MemoizePropsToWatchTestModel> {
+    name: string;
+    desc: string
+    @Memoize(['name']) doNameRandom(t: string): string {
+        return this.name + t + (Math.random() * 10);
+    }
+}
+
+
 describe('@Memoize() Decorator', () => {
-    it('should remember...', () => {
+    it('should remember, no args or propsToWatch', () => {
         const testModel = new MemoizeTestModel().deserialize({
             name: 'test model',
         });
@@ -19,4 +43,48 @@ describe('@Memoize() Decorator', () => {
         const result2 = testModel.doNameRandom();
         expect(result1).toBe(result2);
     });
+
+    it('should remember with args, no propsToWatch', () => {
+        const testModel = new MemoizeArgsTestModel().deserialize({
+            name: 'test model',
+        });
+    
+        const result1 = testModel.doNameRandom('t');
+        const result1a = testModel.doNameRandom('t');
+        const result2 = testModel.doNameRandom('r');
+        expect(result1).toBe(result1a);
+        expect(result1).not.toBe(result2);
+    });
+
+    it('should remember with propsToWatch, no args', () => {
+        const testModel = new MemoizePropsToWatchTestModel().deserialize({
+            name: 'test model',
+            desc: 'this is a desc'
+        });
+
+        const result1 = testModel.doNameRandom();
+        testModel.desc = 'this is a desc updated'
+        const result2 = testModel.doNameRandom();
+        testModel.name = 'test model updated';
+        const result1a = testModel.doNameRandom();
+        expect(result1).toBe(result2);
+        expect(result1).not.toBe(result1a);
+    });
+
+    it('should remember with propsToWatch, and args', () => {
+        const testModel = new MemoizePropsToWatchArgsTestModel().deserialize({
+            name: 'test model',
+            desc: 'this is a desc'
+        });
+
+        const result1 = testModel.doNameRandom('t');
+        const result1a = testModel.doNameRandom('t');
+        testModel.desc = 'this is a desc updated'
+        const result2 = testModel.doNameRandom('r');
+        testModel.name = 'test model updated';
+        const result1b = testModel.doNameRandom('t');
+        expect(result1).not.toBe(result2);
+        expect(result1).toBe(result1a);
+        expect(result1).not.toBe(result1b);
+    });
 });