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')

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

read items in database, plus realtime changes

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.
  .pipe(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()
  .pipe(pull.drain())

If you just want the realtime inserts, use live

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

Example - writing

To write, pipe batch changes into write

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

Example - indexes!

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

like this:

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

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

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

License

MIT