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https://github.com/nhz-io/nhz-io-pouch-db-sync-job


https://github.com/nhz-io/nhz-io-pouch-db-sync-job

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# PouchDB sync job (control)



[![Travis Build][travis]](https://travis-ci.org/nhz-io/nhz-io-pouch-db-sync-job)

[![NPM Version][npm]](https://www.npmjs.com/package/@nhz.io/pouch-db-sync-job)



## Install



```bash

npm i -S @nhz.io/pouch-db-sync-job

```



## Usage



> Intended to be used with [pouchdb-job-scheduler]



```js

const PouchDB = require 'pouchdb'

const sync = require('@nhz.io/pouch-db-sync-job')



const startJob = sync { /* PouchDb sync options */}, databaseA, databaseB

const job = startJob { PouchDB }



...



const res = await job



...

```

## Literate Source



### Imports



    curryN = require 'curry-n'



### Helpers



    assign = (sources...) -> Object.assign {}, sources...



    isString = (maybeString) -> typeof maybeString is 'string'



    getter = (obj, name, fn) -> Object.defineProperty obj, name, {

      configurable: true, enumerable: true, get: fn

    }



### Definitions



> Global Job UID



    uid = 0



> Sync defaults



    def = {



      live: false



      retry: false



      since: 0



    }



### Job generator



    pouchDbSyncJob = (options, databaseA, databaseB, ctx) ->



> Hoist `stop` and `sync` (for Promise below)



      stop = sync = null



> Get pouch from context or global (context comes from queue manager, if any)



      PouchDB = ctx.PouchDB or PouchDB



> Preload databases



      databaseA = new PouchDB databaseA if isString databaseA



      databaseB = new PouchDB databaseB if isString databaseB



> Assign defaults



      options = assign def, options



#### Create and start the job



Job is actually a promise extended with extra properties.



Promise states meaning:



* Promise resolved → sync has finished (Connection might still be open)

* Promise rejected

  * `err` is empty → sync was cancelled

  * otherwise, `err` contains the reason and will be set to `job.error`



>



      job = new Promise (resolve, reject) ->



        sync = ctx.PouchDB.sync databaseA, databaseB, assign options



> Job stopper (`err` is optional - no `err` means manual stop)



        stop = (err) ->



          sync.cancel()



          return if job.done



          job.done = true



          job.error = err or false



          reject job.error



          return job



> Job completer



        complete = (info) ->



          job.info = info if info



          return if job.done



          job.done = true



          job.error = false



> Create result by stripping promise from the job and aliasing job.info



          resolve getter (assign job), 'info', () -> job.info



#### PouchDB sync events



        sync.on 'error', stop



        sync.on 'denied', stop



> Live syncs fire `complete` only when cancelled



        sync.on 'complete', complete



> Applies only to `retry` syncs



        sync.on 'active', -> job.started = true



        sync.on 'paused', (err) -> if err then stop err else complete()



        sync.then(complete).catch(stop)



> Extend the promise and return



      uid = uid + 1



      Object.assign job, {

        uid, options, stop, sync, databases: [ databaseA, databaseB ]

      }



## Exports (Curried)



    module.exports = curryN 4, pouchDbSyncJob



## Tests



    test = require 'tape-async'



    PouchDB = require 'pouchdb-memory'



    pouchDbSyncJob = module.exports



    mkdb = (s = 1, e = 3) ->



      db = new PouchDB "db-#{ Math.random().toString().slice 2 }"



      await db.put { _id: "doc-#{ i }" } for i in [s..e]



      db



> **Job completion**



    test 'job completion', (t) ->



> One-Shot



      dbA = await mkdb 1, 3



      dbB = await mkdb 4, 6



      startJob = pouchDbSyncJob {}, dbA, dbB



      job = startJob { PouchDB }



      res = await job



      t.equals res.info, job.info



      t.deepEqual (await dbA.allDocs()), (await dbB.allDocs()), 'docs match'



      job.stop()



      t.equals res.info, job.info



      t.equals res.info.push.status, 'complete'

      t.equals res.info.pull.status, 'complete'



> Live



      dbA = await mkdb 1, 3



      dbB = await mkdb 4, 6



      startJob = pouchDbSyncJob { live: true, retry: true }, dbA, dbB



      res = await job = startJob { PouchDB }



      t.equals res.info, job.info



      t.deepEqual (await dbA.allDocs()), (await dbB.allDocs()), 'docs match'



      t.equals job.started, true



      t.false job.sync.canceled



      job.stop()



      t.true job.sync.canceled



> **Job failure**



    test 'job failure', (t) ->



      db = await mkdb 1, 3



      startJob = pouchDbSyncJob { live: true, retry: false }, 'http://foo-not-found', db



      try

        await job = startJob { PouchDB }



        t.fail()



      catch err



        t.equals err.status, 500



## Version 1.0.0



## License [MIT](LICENSE)



[travis]: https://img.shields.io/travis/nhz-io/nhz-io-pouch-db-sync-job.svg?style=flat

[npm]: https://img.shields.io/npm/v/@nhz.io/pouch-db-sync-job.svg?style=flat