IndexedDB使用案例

module.exports = {

  dbName: 'dbTest',
  version: 1,
  db: null,
  indexedDB: window.indexedDB || window.webkitIndexedDB,

  // 异步方法改写，包括错误处理的优化
  async openDB() {
    try {
      const request = this.indexedDB.open(this.dbName, this.version);

      // 如果数据库不存在或者版本号更高，触发 onupgradeneeded 事件
      request.onupgradeneeded = (event) => {
        this.db = event.target.result;
        // 确保数据库中已经包含了所有必要的对象存储
        ['mystore', 'mystore01'].forEach(storeName => {
          if (!this.db.objectStoreNames.contains(storeName)) { // 如果没有名为 'mystore' 的对象存储
            this.db.createObjectStore(storeName, { keyPath: 'id' });  // 创建新的对象存储，并设置主键为 'id'
          }
        });
      };

      request.onsuccess = (event) => {
        this.db = event.target.result;
        console.log("Database opened successfully", event.target.result);
      };

      request.onerror = (event) => {
        console.error("Error opening IndexedDB:", event.target.errorCode);
      };
    } catch (error) {
      console.error("Error opening IndexedDB asynchronously:", error);
    }
  },

  // 使用Promise替代回调，优化异步处理
  async addData(myStore, data) {
    try {
      const store = this.getStore(myStore);
      return new Promise((resolve, reject) => {
        const addRequest = store.add(data);
        addRequest.onsuccess = (event) => {
          console.log('添加成功！', event.target.result);
          resolve(event.target.result);
        };
        addRequest.onerror = (event) => {
          console.log('添加失败！', event.target.error);
          reject(event.target.error);
        };
      });
    } catch (error) {
      console.error("Error adding data:", error.name, error.message);
      throw error; // 重新抛出错误，以便调用者可以捕获
    }
  },

  getById(myStore, id) {
    return new Promise((resolve, reject) => {
      const store = this.getStore(myStore);
      const request = store.get(id);
      request.onerror = (event) => {
        console.error('查询数据失败:', event.target.error);
        reject(event.target.error);
      };
      request.onsuccess = (event) => {
        const result = event.target.result;
        console.log('查询数据成功:', result);
        resolve(result);
      };
    });
  },

  // 更新数据方法
  updateById(myStore, data) {
    return this._handleDatabaseRequest(() => {
      const store = this.getStore(myStore);
      return store.put(data);
    }, '更新数据');
  },

  // 删除数据方法
  deleteById(myStore, id) {
    return this._handleDatabaseRequest(() => {
      const store = this.getStore(myStore);
      return store.delete(id);
    }, '删除数据');
  },

  getStore(myStore) {
    if (!this.db) {
      this.openDB(); // 确保数据库已经打开
    }
    if (!this.db.objectStoreNames.contains(myStore)) {
      throw new Error(`Object store ${myStore} does not exist.`);
    }
    const transaction = this.db.transaction(myStore, 'readwrite');
    const store = transaction.objectStore(myStore);
    return store;
  },

  // 私有方法，用于处理数据库请求，减少代码重复
  _handleDatabaseRequest (operation, actionName) {
    try {
      return new Promise((resolve, reject) => {
        const request = operation();
        request.onsuccess = (event) => {
          console.log(`${actionName}成功:`, event.target.result);
          resolve(event.target.result);
        };
        request.onerror = (event) => {
          console.error(`${actionName}失败:`, event.target.error);
          reject(event.target.error);
        };
      });
    } catch (error) {
      console.error(`Error during ${actionName}:`, error.name, error.message);
      throw error;
    }
  }

}