refactored services and expense list

src/app/services/category.service.ts

@@ -1,16 +1,22 @@
-import { Injectable } from '@angular/core';
+import { Injectable, signal } from '@angular/core';
 import { HttpService } from './http.service';
 
 @Injectable({
   providedIn: 'root',
 })
 export class CategoryService {
-  public static readonly CATEGORY_PATH = 'http://localhost:3000/common-cents/categories';
+  private internalCategories = signal<Category[]>([]);
+  public readonly categories = this.internalCategories.asReadonly();
+  public readonly categoryPath = 'http://localhost:3000/common-cents/categories';
 
-  public constructor(private readonly http: HttpService) { }
+  // public categories = signal<Category[]>([]);
 
-  public async getCategories(): Promise<Category[]> {
-    return this.http.get<Category[]>(CategoryService.CATEGORY_PATH);
+  public constructor(private readonly http: HttpService) {
+    void this.fetchCategories();
+  }
+
+  public async fetchCategories(): Promise<void> {
+    this.internalCategories.set(await this.http.get<Category[]>(this.categoryPath));
   }
 }