feat(Angular-query): add Angular auto-refetching example

examples/angular/auto-refetching/.devcontainer/devcontainer.json

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+{
+  "name": "Node.js",
+  "image": "mcr.microsoft.com/devcontainers/javascript-node:22"
+}

examples/angular/auto-refetching/.eslintrc.cjs

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+// @ts-check
+
+/** @type {import('eslint').Linter.Config} */
+const config = {}
+
+module.exports = config

examples/angular/auto-refetching/README.md

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+# TanStack Query Angular auto-refetching example
+
+To run this example:
+
+- `npm install` or `yarn` or `pnpm i` or `bun i`
+- `npm run start` or `yarn start` or `pnpm start` or `bun start`

examples/angular/auto-refetching/angular.json

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+{
+  "$schema": "./node_modules/@angular/cli/lib/config/schema.json",
+  "version": 1,
+  "cli": {
+    "packageManager": "pnpm",
+    "analytics": false,
+    "cache": {
+      "enabled": false
+    }
+  },
+  "newProjectRoot": "projects",
+  "projects": {
+    "auto-refetching": {
+      "projectType": "application",
+      "schematics": {
+        "@schematics/angular:component": {
+          "inlineTemplate": true,
+          "inlineStyle": true,
+          "skipTests": true
+        },
+        "@schematics/angular:class": {
+          "skipTests": true
+        },
+        "@schematics/angular:directive": {
+          "skipTests": true
+        },
+        "@schematics/angular:guard": {
+          "skipTests": true
+        },
+        "@schematics/angular:interceptor": {
+          "skipTests": true
+        },
+        "@schematics/angular:pipe": {
+          "skipTests": true
+        },
+        "@schematics/angular:resolver": {
+          "skipTests": true
+        },
+        "@schematics/angular:service": {
+          "skipTests": true
+        }
+      },
+      "root": "",
+      "sourceRoot": "src",
+      "prefix": "app",
+      "architect": {
+        "build": {
+          "builder": "@angular-devkit/build-angular:application",
+          "options": {
+            "outputPath": "dist/auto-refetching",
+            "index": "src/index.html",
+            "browser": "src/main.ts",
+            "polyfills": ["zone.js"],
+            "tsConfig": "tsconfig.app.json",
+            "assets": ["src/favicon.ico", "src/assets"],
+            "styles": [],
+            "scripts": []
+          },
+          "configurations": {
+            "production": {
+              "budgets": [
+                {
+                  "type": "initial",
+                  "maximumWarning": "500kb",
+                  "maximumError": "1mb"
+                },
+                {
+                  "type": "anyComponentStyle",
+                  "maximumWarning": "2kb",
+                  "maximumError": "4kb"
+                }
+              ],
+              "outputHashing": "all"
+            },
+            "development": {
+              "optimization": false,
+              "extractLicenses": false,
+              "sourceMap": true
+            }
+          },
+          "defaultConfiguration": "production"
+        },
+        "serve": {
+          "builder": "@angular-devkit/build-angular:dev-server",
+          "configurations": {
+            "production": {
+              "buildTarget": "auto-refetching:build:production"
+            },
+            "development": {
+              "buildTarget": "auto-refetching:build:development"
+            }
+          },
+          "defaultConfiguration": "development"
+        },
+        "extract-i18n": {
+          "builder": "@angular-devkit/build-angular:extract-i18n",
+          "options": {
+            "buildTarget": "auto-refetching:build"
+          }
+        }
+      }
+    }
+  }
+}

examples/angular/auto-refetching/package.json

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+{
+  "name": "@tanstack/query-example-angular-auto-refetching",
+  "type": "module",
+  "scripts": {
+    "ng": "ng",
+    "start": "ng serve",
+    "build": "ng build",
+    "watch": "ng build --watch --configuration development"
+  },
+  "private": true,
+  "dependencies": {
+    "@angular/common": "^19.0.0",
+    "@angular/compiler": "^19.0.0",
+    "@angular/core": "^19.0.0",
+    "@angular/platform-browser": "^19.0.0",
+    "@angular/platform-browser-dynamic": "^19.0.0",
+    "@tanstack/angular-query-experimental": "^5.61.6",
+    "rxjs": "^7.8.1",
+    "tslib": "^2.6.3",
+    "zone.js": "^0.15.0"
+  },
+  "devDependencies": {
+    "@angular-devkit/build-angular": "^19.0.2",
+    "@angular/build": "^19.0.0",
+    "@angular/cli": "^19.0.2",
+    "@angular/compiler-cli": "^19.0.0",
+    "typescript": "5.6.3"
+  }
+}

examples/angular/auto-refetching/src/app/app.component.ts

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+import { ChangeDetectionStrategy, Component } from '@angular/core'
+import { AutoRefetchingExampleComponent } from './components/auto-refetching.component'
+
+@Component({
+  changeDetection: ChangeDetectionStrategy.OnPush,
+  selector: 'app-root',
+  standalone: true,
+  template: `<auto-refetching-example />`,
+  imports: [AutoRefetchingExampleComponent],
+})
+export class AppComponent {}

examples/angular/auto-refetching/src/app/app.config.ts

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+import {
+  provideHttpClient,
+  withFetch,
+  withInterceptors,
+} from '@angular/common/http'
+import {
+  QueryClient,
+  provideTanStackQuery,
+  withDevtools,
+} from '@tanstack/angular-query-experimental'
+import { mockInterceptor } from './interceptor/mock-api.interceptor'
+import type { ApplicationConfig } from '@angular/core'
+
+export const appConfig: ApplicationConfig = {
+  providers: [
+    provideHttpClient(
+      withFetch(),
+      withInterceptors([mockInterceptor]),
+    ),
+    provideTanStackQuery(
+      new QueryClient({
+        defaultOptions: {
+          queries: {
+            gcTime: 1000 * 60 * 60 * 24, // 24 hours
+          },
+        },
+      }),
+      withDevtools(),
+    ),
+  ],
+}

examples/angular/auto-refetching/src/app/components/auto-refetching.component.html

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+<div>
+  <h1>Auto Refetch with stale-time set to {{ intervalMs() }}ms</h1>
+  <p>
+    This example is best experienced on your own machine, where you can open
+    multiple tabs to the same localhost server and see your changes propagate
+    between the two.
+  </p>
+  <label>
+    Query Interval speed (ms):
+    <input [value]="intervalMs()" (input)="inputChange($event)" />
+  </label>
+  <h2>Todo List</h2>
+
+  <input placeholder="Enter something" (keydown.enter)="addItem($event)" />
+  <ul>
+    @for (item of tasks.data(); track item) {
+      <li>{{ item }}</li>
+    }
+  </ul>
+  <div>
+    <button (click)="clearTasks()">Clear All</button>
+  </div>
+</div>

examples/angular/auto-refetching/src/app/components/auto-refetching.component.ts

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+import {
+  ChangeDetectionStrategy,
+  Component,
+  inject,
+  signal,
+} from '@angular/core'
+import {
+  injectMutation,
+  injectQuery,
+  QueryFunctionContext,
+} from '@tanstack/angular-query-experimental'
+import { fromEvent, lastValueFrom, takeUntil } from 'rxjs'
+import { TasksService } from '../services/tasks.service'
+
+@Component({
+  changeDetection: ChangeDetectionStrategy.OnPush,
+  selector: 'auto-refetching-example',
+  standalone: true,
+  templateUrl: './auto-refetching.component.html',
+  imports: [],
+})
+export class AutoRefetchingExampleComponent {
+  #tasksService = inject(TasksService)
+
+  intervalMs = signal(1000)
+
+  tasks = injectQuery(() => this.#tasksService.allTasks(this.intervalMs()))
+
+  addMutation = injectMutation(() => this.#tasksService.addTask())
+  clearMutation = injectMutation(() => this.#tasksService.clearAllTasks())
+
+  clearTasks() {
+    this.clearMutation.mutate()
+  }
+
+  inputChange($event: Event) {
+    const target = $event.target as HTMLInputElement
+    this.intervalMs.set(Number(target.value))
+  }
+
+  addItem($event: Event) {
+    const target = $event.target as HTMLInputElement
+    const value = target.value
+    this.addMutation.mutate(value)
+    target.value = ''
+  }
+}

examples/angular/auto-refetching/src/app/interceptor/mock-api.interceptor.ts

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+/**
+ * MockApiInterceptor is used to simulate API responses for `/api/tasks` endpoints.
+ * It handles the following operations:
+ * - GET: Fetches all tasks from localStorage.
+ * - POST: Adds a new task to localStorage.
+ * - DELETE: Clears all tasks from localStorage.
+ * Simulated responses include a delay to mimic network latency.
+ */
+import { Injectable } from '@angular/core'
+import { HttpResponse } from '@angular/common/http'
+import { delay, of } from 'rxjs'
+import type {
+    HttpEvent,
+    HttpHandler,
+    HttpHandlerFn,
+    HttpInterceptorFn,
+    HttpRequest,
+} from '@angular/common/http'
+import type { Observable } from 'rxjs'
+
+
+export const mockInterceptor: HttpInterceptorFn = (
+    req: HttpRequest<unknown>, next: HttpHandlerFn
+): Observable<HttpEvent<any>> => {
+
+    const respondWith = (
+        status: number,
+        body: any,
+    ) => of(new HttpResponse({ status, body })).pipe(delay(100))
+    if (req.url === '/api/tasks') {
+
+        switch (req.method) {
+            case 'GET':
+                return respondWith(
+                    200,
+                    JSON.parse(localStorage.getItem('tasks') || '[]'),
+                )
+            case 'POST':
+                const tasks = JSON.parse(localStorage.getItem('tasks') || '[]')
+                tasks.push(req.body)
+                localStorage.setItem('tasks', JSON.stringify(tasks))
+                return respondWith(201, {
+                    status: 'success',
+                    task: req.body,
+                })
+            case 'DELETE':
+                localStorage.removeItem('tasks')
+                return respondWith(200, { status: 'success' })
+        }
+    }
+    return next(req)
+}

examples/angular/auto-refetching/src/app/services/tasks.service.ts

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+import { HttpClient } from '@angular/common/http'
+import { Injectable, inject } from '@angular/core'
+import { QueryClient, QueryFunctionContext, mutationOptions, queryOptions } from '@tanstack/angular-query-experimental'
+
+import { fromEvent, lastValueFrom, takeUntil } from 'rxjs'
+
+@Injectable({
+    providedIn: 'root',
+})
+export class TasksService {
+    #queryClient = inject(QueryClient) // Manages query state and caching
+    #http = inject(HttpClient) // Handles HTTP requests
+
+    /**
+     * Fetches all tasks from the API.
+     * Returns an observable containing an array of task strings.
+     */
+    allTasks = (intervalMs: number) => queryOptions({
+        queryKey: ['tasks'],
+        queryFn: () => {
+            return lastValueFrom(
+                this.#http.get<Array<string>>('/api/tasks'),
+            )
+        },
+        refetchInterval: intervalMs,
+    })
+
+    /**
+     * Creates a mutation for adding a task.
+     * On success, invalidates and refetches the "tasks" query cache to update the task list.
+     */
+    addTask() {
+        return mutationOptions({
+            mutationFn: (task: string) =>
+                lastValueFrom(this.#http.post('/api/tasks', task)),
+            mutationKey: ['tasks'],
+            onSuccess: () => {
+                this.#queryClient.invalidateQueries({ queryKey: ['tasks'] })
+            },
+        })
+    }
+
+    /**
+     * Creates a mutation for clearing all tasks.
+     * On success, invalidates and refetches the "tasks" query cache to ensure consistency.
+     */
+    clearAllTasks() {
+        return mutationOptions({
+            mutationFn: () => lastValueFrom(this.#http.delete('/api/tasks')),
+            mutationKey: ['clearTasks'],
+            onSuccess: () => {
+                this.#queryClient.invalidateQueries({ queryKey: ['tasks'] })
+            },
+        })
+    }
+}

examples/angular/auto-refetching/src/index.html

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+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8" />
+    <title>TanStack Query Angular auto-refetching example</title>
+    <base href="/" />
+    <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <link rel="icon" type="image/x-icon" href="favicon.ico" />
+  </head>
+  <body>
+    <app-root></app-root>
+  </body>
+</html>