Implementing Offline Capabilities

if (navigator.onLine) {
  console.log("Online");
} else {
  console.log("Offline");
}

import { SQLiteDB } from '@ionic-native/sqlite';

const db = await SQLiteDB.create({
  name: 'mydb.db',
  location: 'default'
});

await db.executeSql('CREATE TABLE IF NOT EXISTS users (id INTEGER PRIMARY KEY, name TEXT)');

await db.executeSql('INSERT INTO users (name) VALUES ('John Doe')');

import { HttpClient } from '@angular/common/http';
import { CacheService } from 'ionic-cache';

constructor(private http: HttpClient, private cache: CacheService) {}

getCachedData() {
  return this.cache.get('api-data', () => {
    return this.http.get('https://api.example.com/data');
  }, {
    ttl: 600000, // 10 minutes
    strategy: 'cache-first'
  });
}

import { HttpClient } from '@angular/common/http';
import { Injectable } from '@angular/core';

@Injectable({
  providedIn: 'root'
})
export class DataService {
  private apiUrl = 'https://api.example.com/data';

  constructor(private http: HttpClient) {}

  async syncData() {
    const localData = await this.getLocalData();
    const serverData = await this.http.get(this.apiUrl).toPromise();

    // Simple diff and sync logic
    const changes = this.calculateChanges(localData, serverData);
    await this.applyChanges(changes);

    return { success: true };
  }

  private async getLocalData() {
    // Fetch from local storage or database
    return JSON.parse(localStorage.getItem('localData') || '[]');
  }

  private calculateChanges(local, server) {
    // Logic to detect differences
    return { added: [], updated: [], deleted: [] };
  }

  private async applyChanges(changes) {
    // Apply changes to local storage or database
    localStorage.setItem('localData', JSON.stringify(changes));
  }
}

import { IonicForm } from '@ionic/offline';

const form = new IonicForm({
  formId: 'user-profile',
  offlineStorageKey: 'user-data',
  autoSaveInterval: 3000
});

form.onSave((data) => {
  console.log('Saved offline data:', data);
});

async function submitForm(formId) {
  const form = new IonicForm({ formId });
  const data = await form.getOfflineData();

  if (navigator.onLine) {
    // Submit to server
    const response = await fetch('/api/submit', {
      method: 'POST',
      body: JSON.stringify(data)
    });
    await form.clearOfflineData();
  } else {
    // Store for later
    await form.saveOffline(data);
  }
}

import Dexie from 'dexie';

class MyDatabase extends Dexie {
  constructor() {
    super('MyAppDB');
    this.version(1).stores({
      items: '++id, name, description'
    });
  }
}

const db = new MyDatabase();

// Add item to local storage
db.items.add({ name: 'Item 1', description: 'Description of item 1' });

// Retrieve items
db.items.toArray().then(items => {
  console.log(items);
});

const handleOverwriteConflict = (localData, serverData) => {
  if (localData.version < serverData.version) {
    // Server version is newer, apply it
    return serverData;
  } else if (localData.version > serverData.version) {
    // Local version is newer, push it to server
    return localData;
  } else {
    // Versions match, no conflict
    return null;
  }
};

const fetchWithEtag = async (url, etag) => {
  const response = await fetch(url, {
    headers: { 'If-None-Match': etag }
  });
  if (response.status === 304) {
    // No changes, use cached data
    return { changed: false };
  } else {
    const data = await response.json();
    return { changed: true, data, etag: response.headers.get('ETag') };
  }
};

const config = {
  cache: true,
  maxAge: 86400000,
  strategy: 'cache-first'
};

// Apply to Ionic app build process

import { Network } from '@capacitor/network';

async function checkNetworkStatus() {
  const status = await Network.getStatus();
  const offlineIndicator = document.getElementById('offline-indicator');

  if (!status.connected) {
    offlineIndicator.style.display = 'block';
  } else {
    offlineIndicator.style.display = 'none';
  }
}

Network.addListener('networkStatusChange', checkNetworkStatus);

import { Network } from '@capacitor/network';
import { Toast } from '@capacitor/toast';

async function showOfflineToast() {
  const status = await Network.getStatus();
  if (!status.connected) {
    await Toast.show({
      message: 'You are offline. Some features may not work.',
      duration: 'long'
    });
  }
}

import { TestBed } from '@angular/core/testing';
import { HttpClientTestingModule } from '@angular/common/http/testing';
import { Network } from '@ionic-native/network/ngx';

describe('Network Service', () => {
  let network: Network;

  beforeEach(() => {
    TestBed.configureTestingModule({
      imports: [HttpClientTestingModule],
      providers: [Network]
    });
    network = TestBed.inject(Network);
  });

  it('should detect offline state', () => {
    spyOn(network, 'onDisconnect').and.returnValue(Promise.resolve());
    expect(network.onDisconnect).toHaveBeenCalled();
  });
});