Serverless JSON database using COS(Cloud Object Storage)
npm install @slsplus/db
Serverless JSON database using
COS(Cloud Object Storage), forked by
lowdb
``sh`
npm install @slsplus/db --save
`js
const slsdb = require('@slsplus/db');
const COSAsync = require('@slsplus/db/adapters/COSAsync');
const adapter = new COSAsync('serverless-db.json', {
region: 'COS region',
bucket: 'COS bucket name with appid',
secretId: 'COS SecretId',
secretKey: 'COS SecretKey',
});
const db = await slsdb(adapter);
// Set some defaults (required if your JSON file is empty)
await db.defaults({ posts: [], user: {}, count: 0 }).write();
// Add a post
await db
.get('posts')
.push({ id: 1, title: 'lowdb is awesome' })
.write();
// Set a user using Lodash shorthand syntax
await db.set('user.name', 'typicode').write();
// Increment count
await db.update('count', (n) => n + 1).write();
// Get all posts
await db.get('posts').value();
`
Data is saved to serverless-db.json in COS
`json`
{
"posts": [{ "id": 1, "title": "lowdb is awesome" }],
"user": {
"name": "typicode"
},
"count": 1
}
You can use any of the powerful lodash functions,
like _.get and
_.find with shorthand syntax.
`js`
// For performance, use .value() instead of .write() if you're only reading from db
await db
.get('posts')
.find({ id: 1 })
.value();
It only supports Node and uses lodash API, so it's very simple to learn.
Actually, if you know Lodash, you already know how to use lowdb :wink:
> - Because @slsplus/db interacts with cloud, so it's suggested to callwrite()
> method(save data to cloud), after all database operations.@slsplus/db
> - doesn't support Cluster and may have issues with very large
> JSON files (~200MB).
`sh`
npm install @slsplus/db --save
Alternatively, if you're using yarn
`sh`
yarn add @slsplus/db
A UMD build is also available on unpkg for testing and quick prototyping:
`html`
low(adapter)
Returns a lodash chain with additional
properties and functions described below.
db.[...].write() and db.[...].value()
write() writes database to state.
On the other hand, value() is just
\_.prototype.value() and
should be used to execute a chain that doesn't change database state.
`js`
await db.set('user.name', 'yugasun').write();
Please note that db.[...].write() is syntactic sugar and equivalent to
`js
await db.set('user.name', 'yugasun').value();
await db.write();
`
db.\_
Database lodash instance. Use it to add your own utility functions or
third-party mixins like
underscore-contrib or
lodash-id.
`js
db._.mixin({
second: function(array) {
return array[1];
},
});
db.get('posts')
.second()
.value();
`
db.getState()
Returns database state.
`js`
db.getState(); // { posts: [ ... ] }
db.setState(newState)
Replaces database state.
`js`
const newState = {};
db.setState(newState);
db.write()
Persists database using adapter.write, it will write data to a JSON file, and
upload to COS.
`js`
db.write().then(() => console.log('State has been saved'));
db.read()
Reads source using storage.read option, it will download a JSON file from COS,
and read data from it.
`js`
db.read().then(() => console.log('State has been updated'));
Please note this only applies to adapters bundled with Lowdb. Third-party
adapters may have different options.
For convenience, COSAsync accept the following options:
- defaultValue if file doesn't exist, this value will be used to set the
initial state (default: {})JSON.stringify
- serialize/deserialize functions used before writing and after reading
(default: and JSON.parse)
`js`
const adapter = new COSAsync('array.yaml', {
region: 'COS region',
bucket: 'COS bucket name with appid',
secretId: 'COS SecretId',
secretKey: 'COS SecretKey',
defaultValue: [],
serialize: (array) => toYamlString(array),
deserialize: (string) => fromYamlString(string),
});
Check if posts exists.
`js`
db.has('posts').value();
Set posts.
`js`
db.set('posts', []).write();
Sort the top five posts.
`js`
db.get('posts')
.filter({ published: true })
.sortBy('views')
.take(5)
.value();
Get post titles.
`js`
db.get('posts')
.map('title')
.value();
Get the number of posts.
`js`
db.get('posts')
.size()
.value();
Get the title of first post using a path.
`js`
db.get('posts[0].title').value();
Update a post.
`js`
db.get('posts')
.find({ title: 'low!' })
.assign({ title: 'hi!' })
.write();
Remove posts.
`js`
db.get('posts')
.remove({ title: 'low!' })
.write();
Remove a property.
`js`
db.unset('user.name').write();
Make a deep clone of posts.
`js`
db.get('posts')
.cloneDeep()
.value();
Being able to get data using an id can be quite useful, particularly in servers.
To add id-based resources support to lowdb, you have 2 options.
shortid is more minimalist and returns a
unique id that you can use when creating resources.
`js
const shortid = require('shortid');
const postId = await db
.get('posts')
.push({ id: shortid.generate(), title: 'low!' })
.write().id;
const post = await db
.get('posts')
.find({ id: postId })
.value();
`
lodash-id provides a set of helpers for
creating and manipulating id-based resources.
`js
const lodashId = require('lodash-id');
const COSAsync = require('@slsplus/db/adapters/COSAsync');
const adapter = new COSAsync('serverless-db.json', {
region: 'COS region',
bucket: 'COS bucket name with appid',
secretId: 'COS SecretId',
secretKey: 'COS SecretKey',
});
const db = await low(adapter);
db._.mixin(lodashId);
// We need to set some default values, if the collection does not exist yet
// We also can store our collection
const collection = db.defaults({ posts: [] }).get('posts');
// Insert a new post...
const newPost = collection.insert({ title: 'low!' }).write();
// ...and retrieve it using its id
const post = collection.getById(newPost.id).value();
`
COSAsync, FileAsync and LocalStorage accept custom serialize anddeserialize functions. You can use them to add encryption logic.
`js`
const adapter = new COSAsync('serverless-db.json', {
region: 'COS region',
bucket: 'COS bucket name with appid',
secretId: 'COS SecretId',
secretKey: 'COS SecretKey',
serialize: (data) => encrypt(JSON.stringify(data)),
deserialize: (data) => JSON.parse(decrypt(data)),
});
@slsplus/db` is a convenient method for storing data without setting up a
database server. It is fast enough and safe to be used as an embedded database.
However, if you seek high performance and scalability more than simplicity, you
should probably stick to traditional databases like MongoDB.
MIT