pull-level

pull-level

pull-stream interface to levelup

Example - reading

read items in database.

var pl = require('pull-level')
var pull = require('pull-stream')

var db = require('levelup')('/tmp/pull-level-example')

pull(pl.read(db), pull.collect(console.log))

read items in database, plus realtime changes

pull(
  pl.read(db, {tail: true}),
  //log data as it comes,
  //because tail will keep the connection open
  //so we'll never see the end otherwise.
  pull.through(console.log),
  //note, pull-streams will not drain unless something is
  //pulling the data through, so we have to add drain
  //even though the data we want is coming from pull.through()
  pull.drain()
)

If you just want the realtime inserts, use live

pull(
  pl.live(db, {tail: true}),
  pull.through(console.log),
  pull.drain()
)

Example - writing

To write, pipe batch changes into write

pull(
  pull.values([
    {key: 0, value: 'zero', type: 'put'},
    {key: 1, value: 'one',  type: 'put'},
    {key: 2, value: 'two',  type: 'put'},
  ]),
  pl.write(db)
)

If you are lazy/busy, you can leave off type. In that case, if value is non-null, the change is considered a put else, a del.

pull(
  pull.values([
    {key: 0, value: 'zero'},
    {key: 1, value: 'one'},
    {key: 2, value: 'two'},
  ]), 
  pl.write(db)
)

Example - indexes!

With pull-level it's easy to create indexes. just save a pointer to the key.

like this:

pull(
  pull.values([
    {key: key, value: VALUE, type: 'put'},
    {key: '~INDEX~' + VALUE.prop, value: key,  type: 'put'},
  ]),
  pl.write(db)
)

then, when you want to do a read, use asyncMap

pull(
  pl.read(db, {min: '~INDEX~', max: '~INDEX~~'})
  pull.asyncMap(function (e, cb) {
    db.get(e.value, function (value) {
      cb(null, {key: e.value, value: value})
    })
  }),
  pull.collect(console.log)
)

License

MIT