uniapp stores information and updates are not lost

With the rapid development of modern technology, mobile applications have become an indispensable part of our lives, and the development technology in them is also constantly expanding. Among them, uniapp has become the first choice of many developers, not only can develop multiple platforms at the same time, but also without a lot of duplication of work. However, the way uniapp is stored can sometimes lead to the loss of important data. In this article, we will explore how to use uniapp to store information and update it without losing it.

1. Methods of storing information

Uniapp’s storage is divided into two methods: local storage and remote storage. Among them, local storage refers to storing data locally on the device, including local cache, database, files, etc.; remote storage refers to storing data on the server and obtaining data online. In actual development, it is necessary to choose an appropriate storage method according to different business needs.

1. Local cache

Local cache is one of the most commonly used local storage methods. It can be operated through the API that comes with uniapp, such as:

uni.setStorageSync('key', 'value') // 存储数据
uni.getStorageSync('key') // 获取数据

This method can store data in the local cache and use it immediately when needed. However, it should be noted that there is a size limit for locally cached data. If you need to store a large amount of data, it is recommended to use other local storage methods.

2. Database

The database is a local storage method used to store large amounts of data. It can be operated through the WebSQL, IndexedDB and SQLite databases that come with uni-app. , such as:

const db = uni.requireNativePlugin('uni-sqlite'); // 调用sqlite插件
db.execSQL({
  sql: 'CREATE TABLE IF NOT EXISTS user(id INTEGER PRIMARY KEY,name TEXT,age INTEGER)'
}); // 创建表
db.execSQL({
  sql: 'INSERT INTO user(name,age) VALUES(?,?)',
  args: ['Tom',18]
}); // 插入数据
db.execSQL({
  sql: 'SELECT * FROM user',
  success(res) {
    console.log(res);
  }
}); // 查询数据

This method can store a large amount of data locally, and can be flexibly queried and modified through SQL statements. However, it should be noted that different platforms have different database support, and the method needs to be adjusted according to the actual situation. and parameters.

3. File storage

File storage is a method of storing data in local files. You can use the API that comes with uni-app to operate, such as:

uni.saveFile({
  tempFilePath: 'tempFilePath',
  success(res) {
    console.log(res.savedFilePath);
  }
}); // 保存文件
uni.getFileSystemManager().readFile({
  filePath: 'filePath',
  encoding: 'utf8',
  success(res) {
    console.log(res.data);
  }
}); // 读取文件

This method can store complex data types, such as pictures, audio, videos, etc., but it should be noted that file storage is not easy to query and modify.

2. Method of updating information

During the application development process, it is often necessary to update the stored information. Generally speaking, there are two ways of updating: full update and incremental update. Full update means that every update requires all data to be re-uploaded to the server or local storage; incremental update is an incremental update based on existing data, and only new data is uploaded or modified.

1. Full update

Full update is a relatively simple and common update method. Just re-upload or store the data every time it needs to be updated. However, it should be noted that if the amount of data is too large, it may consume a lot of time and bandwidth resources and put pressure on the network and system.

2. Incremental update

Incremental update refers to the way to update new data based on existing data. Usually, more complex algorithms can be used to update the data. Compare and update. This method can save a lot of time and bandwidth resources, and improve update efficiency to a certain extent.

3. Methods to prevent data loss

In uniapp, data loss may be caused by various reasons, such as program crash, system upgrade, user manual deletion, etc. In this case, the stored data needs to be backed up and restored.

1. Data backup

Data backup refers to copying the stored data to another location to back up the data in case of data loss. You can use the file storage method that comes with uniapp to copy the data to other files, such as:

uni.saveFile({
  tempFilePath: 'tempFilePath',
  success(res) {
    console.log(res.savedFilePath);
    // 将数据拷贝到备份文件中
    uni.getFileSystemManager().copyFile({
      srcPath: res.savedFilePath,
      destPath: 'backupFilePath',
      success() {
        console.log('backup success');
      }
    });
  }
}); // 备份数据

2. Data recovery

Data recovery means after the data is lost, Re-import the backup data into the system. You can use the file reading and writing functions that come with uniapp to import the backup data into the system, such as:

uni.getFileSystemManager().readFile({
  filePath: 'backupFilePath',
  encoding: 'utf8',
  success(res) {
    console.log(res.data);
    // 将备份数据写入系统中
    uni.setStorageSync('key', res.data);
  }
}); // 读取备份数据

This method can restore the data on the basis of the backup data after the data is lost, ensuring that the data It will not be lost due to unexpected circumstances.

Summary

In uniapp development, it is a very important issue to prevent the storage information from being lost when updated. By understanding the storage and update methods of uniapp, as well as methods to prevent data loss, you can ensure the data integrity and stability of the application system. In actual development, it is necessary to select appropriate storage methods according to different business needs, and to back up and restore data reasonably to ensure data security.

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