ipfs / Interface Datastore
Programming Languages
interface-datastore
Implementation of the datastore interface in JavaScript
Lead Maintainer
Table of Contents
Implementations
- Backed Implementations
- Memory:
src/memory
- level:
datastore-level
(supports any levelup compatible backend) - File System:
datstore-fs
- Memory:
- Wrapper Implementations
- Mount:
datastore-core/src/mount
- Keytransform:
datstore-core/src/keytransform
- Sharding:
datastore-core/src/sharding
- Tiered:
datstore-core/src/tiered
- Namespace:
datastore-core/src/namespace
- Mount:
If you want the same functionality as go-ds-flatfs, use sharding with fs.
const FsStore = require('datastore-fs')
const ShardingStore = require('datastore-core').ShardingDatatstore
const NextToLast = require('datastore-core').shard.NextToLast
const fs = new FsStore('path/to/store')
// flatfs now works like go-flatfs
const flatfs = await ShardingStore.createOrOpen(fs, new NextToLast(2))
Install
$ npm install interface-datastore
Usage
Wrapping Stores
const MemoryStore = require('interface-datastore').MemoryDatastore
const MountStore = require('datastore-core').MountDatastore
const Key = require('interface-datastore').Key
const store = new MountStore({ prefix: new Key('/a'), datastore: new MemoryStore() })
Test suite
Available under src/tests.js
describe('mystore', () => {
require('interface-datastore/src/tests')({
async setup () {
return instanceOfMyStore
},
async teardown () {
// cleanup resources
}
})
})
API
Keys
To allow a better abstraction on how to address values, there is a Key
class which is used as identifier. It's easy to create a key from a Buffer
or a string
.
const a = new Key('a')
const b = new Key(new Buffer('hello'))
The key scheme is inspired by file systems and Google App Engine key model. Keys are meant to be unique across a system. They are typically hierarchical, incorporating more and more specific namespaces. Thus keys can be deemed 'children' or 'ancestors' of other keys:
new Key('/Comedy')
new Key('/Comedy/MontyPython')
Also, every namespace can be parameterized to embed relevant object information. For example, the Key name
(most specific namespace) could include the object type:
new Key('/Comedy/MontyPython/Actor:JohnCleese')
new Key('/Comedy/MontyPython/Sketch:CheeseShop')
new Key('/Comedy/MontyPython/Sketch:CheeseShop/Character:Mousebender')
Methods
The exact types can be found in
src/index.js
.
These methods will be present on every datastore. Key
always means an instance of the above mentioned Key type. Every datastore is generic over the Value
type, though currently all backing implementations are implemented only for Buffer
.
has(key)
-> Promise<Boolean>
key: Key
Check for the existence of a given key
const exists = await store.has(new Key('awesome'))
console.log('is it there', exists)
put(key, value)
-> Promise
key: Key
value: Value
Store a value with the given key.
await store.put(new Key('awesome'), new Buffer('datastores'))
console.log('put content')
get(key)
-> Promise<Value>
key: Key
Retrieve the value stored under the given key.
const value = await store.get(new Key('awesome'))
console.log('got content: %s', value.toString())
// => got content: datastore
delete(key)
-> Promise
key: Key
Delete the content stored under the given key.
await store.delete(new Key('awesome'))
console.log('deleted awesome content :(')
query(query)
-> Iterable
-
query: Query
see below for possible values
Search the store for some values. Returns an Iterable with each item being a Value
.
// retrieve __all__ values from the store
let list = []
for await (const value of store.query({})) {
list.push(value)
}
console.log('ALL THE VALUES', list)
Query
Object in the form with the following optional properties
-
prefix: string
(optional) - only return values where the key starts with this prefix -
filters: Array<Filter<Value>>
(optional) - filter the results according to the these functions -
orders: Array<Order<Value>>
(optional) - order the results according to these functions -
limit: Number
(optional) - only return this many records -
offset: Number
(optional) - skip this many records at the beginning -
keysOnly: Boolean
(optional) - Only return keys, no values.
batch()
This will return an object with which you can chain multiple operations together, with them only being executed on calling commit
.
const b = store.batch()
for (let i = 0; i < 100; i++) {
b.put(new Key(`hello${i}`), new Buffer(`hello world ${i}`))
}
await b.commit()
console.log('put 100 values')
put(key, value)
key: Key
value: Value
Queue a put operation to the store.
delete(key)
key: Key
Queue a delete operation to the store.
commit()
-> Promise
Write all queued operations to the underyling store. The batch object should not be used after calling this.
open()
-> Promise
Opens the datastore, this is only needed if the store was closed before, otherwise this is taken care of by the constructor.
close()
-> Promise
Close the datastore, this should always be called to ensure resources are cleaned up.
Contribute
PRs accepted.
Small note: If editing the Readme, please conform to the standard-readme specification.
License
MIT 2017 © IPFS