@abibv/kval-dstore 中文文档教程

Question

kval-dstore

一个简单的基于文件的键值数据存储，支持 nodejs 中的基本 CRUD 操作。

它创建一个 json 文件，可以用作键值数据库用于学习目的，甚至用于微应用程序。

它提供了五种不同的 API 来访问键值数据存储。

• write(object [,path])
• read([path])
• update(data, key [,path])
• delete([path])
• calcFileSize()

Initializing data store

new dstore(filename [,sizeLimit, initData]);

• filename (String) - The file name with its path for the json file.
• [optional] sizeLimit (String) - Specifies the sizeLimit in MegaByte (default is 1024 MB)
• [optional] initData (JSON object) - Initial data to be stored at the time of file creation (default is empty json object {})

const dstore = require('@abibv/kval-dstore');

const store = new dstore('./dstore.json');
(or)
const store = new dstore(__dirname + '/dstore.json');

Write the data

store.write(object [,path]);

• object (JSON object) - Data to be stored.
• [optional] path (string) - Key path where the data should be placed (should be referred from the root) (default is the root of the json data '/')

write 是一个 不返回任何内容的异步方法。

var object = {
  name: 'myname',
  no: 123456789,
  timeSpent: {
    tech: '50%',
    music: '30%',
    sleep: '20%',
  }
};


//Write the data at the root

store.write(object)
  .then(() => { console.log('data written'); })
  .catch((error) => { console.log(error); });


//Write the data at the specified 

store.write(object, '/department/year/students/')
  .then(() => { console.log('data written'); })
  .catch((error) => { console.log(error); });

Read the data

store.read([path]);

• [optional] path (String) - JSON key path from where the data should be read. (default is root '/')

如果没有指定路径，则读取整个数据。

read 是一个返回读取数据的异步方法。

store.read('/department/year/students/')
  .then((data) => { console.log(data); })
  .catch((error) => { console.log(error); });

Update the data

store.update(data, key [,path]);

• data (any) - data to be updated.
• key (String) - JSON key whose value should be replaced (must be a Single key string).
• [optional] path (String) - path of the key in the JSON object referred from the root '/'.

update 是一个不返回任何内容的异步方法。

store.update({ misc: '10%' }, '/timeSpent')
  .then(() => { console.log('updated'); })
  .catch((err) => { console.log(err); });

Delete a Data

store.delete([path])

• [optional] path (String path) - JSON key path from where the key-value pair should be deleted (default is root '/')

如果没有指定路径，则包含该文件的整个数据存储将被删除

delete 是一个 < strong>异步方法，不返回任何内容。

store.delete('/timeSpent')
  .then(() => { console.log('timeSpent object deleted'); })
  .catch((error) => { console.log(error); });

Calculate data store size

store.calcFileSize()

calcFileSize 是一种同步方法，它以兆字节为单位返回数据存储文件的大小。

 console.log(store.calcFileSize());