add dat.createBlobReadStream

docs/api.md

@@ -158,6 +158,20 @@ Returns a writable stream that you can stream a binary blob attachment into. Cal

If specified `row` should be a JS object you want to attach the blob to, obeying the same update/conflict rules as `db.put`. If not specified a new row will be created.

## createBlobReadStream

```js
var blobWriter = db.createBlobReadStream(key, filename, [options])
```

Returns a readable stream of blob data.

`key` is the key of the row where the blob is stored. `filename` is the name of the attached blob. both are required.

### Options

* `version` (default latest) - the version of the row to get

## listen

```js

index.js

@@ -1,6 +1,7 @@
var fs = require('fs')
var tty = require('tty')
var path = require('path')
var os = require('os')
var debug = require('debug')('dat.init')

var request = require('request').defaults({json: true})
@@ -77,8 +78,9 @@ function Dat(dir, opts, onReady) {
        loadMeta()
      })
    }
    // the 2000 here is thanks to windows server, which errors w/ lower values
    if (!tty.isatty(0)) setTimeout(read, 2000)
    // windows server fails when timeout is lower than 2000
    // timeout if called from CLI && is not a mac
    if (!tty.isatty(0) && !(os.platform().match('darwin'))) setTimeout(read, 2000)
    else read()
  }
  

lib/commands.js

@@ -454,6 +454,26 @@ dat.createBlobWriteStream = function(options, doc, cb) {
  return blobWrite
}


dat.createBlobReadStream = function(key, name, opts) {
  var self = this
  
  if (!opts) opts = {}
  
  var proxy = through()
  
  self.get(key, opts, function(err, doc) {
    if (err) return proxy.emit('error', err)
    if (!doc.attachments[name]) return proxy.emit('error', new Error('file is not attached to row'))
    
    var readStream = self.blobs.createReadStream(doc.attachments[name].hash)
    readStream.pipe(proxy)
  })
  
  return proxy
}


dat.createWriteStream = function(options) {
  return writeStream(this, options)
}

lib/rest-handler.js

@@ -44,14 +44,11 @@ RestHandler.prototype.blob = function(req, res, opts) {
  var self = this
  if (req.method === 'GET') {
    var id = opts.id
    self.dat.get(id, function(err, doc) {
      var attachment
      if (doc && doc.attachments) {
        attachment = doc.attachments[opts.filename]
      }
      if (err || !attachment) return self.error(res, 404, {"error": "Not Found"})
      self.dat.blobs.createReadStream(attachment.hash).pipe(res)
    var blob = self.dat.createBlobReadStream(opts.id, opts.filename, opts)
    blob.on('error', function(err) {
      return self.error(res, 404, {"error": "Not Found"})
    })
    blob.pipe(res)
    return
  }
  

test/tests/write-streams.js

@@ -27,6 +27,33 @@ module.exports.blobWriteStream = function(test, common) {
  })
}

module.exports.blobReadStream = function(test, common) {
  test('getting a blob read stream by row key + name', function(t) {
    common.getDat(t, function(dat, done) {
      
      var ws = dat.createBlobWriteStream('write-streams.js', function(err, doc) {
        t.notOk(err, 'no blob write err')
        var attachment = doc.attachments['write-streams.js']
        t.ok(attachment, 'doc has attachment')

        var rs = dat.createBlobReadStream(doc.id, 'write-streams.js')

        rs.on('error', function(e) {
          t.false(e, 'no read stream err')
          done()
        })

        rs.pipe(concat(function(file) {
          t.equal(file.length, attachment.size, 'attachment size is correct')
          done()
        }))
      })
      
      fs.createReadStream(path.join(__dirname, 'write-streams.js')).pipe(ws)
    })
  })
}

module.exports.singleNdjsonObject = function(test, common) {
  test('piping a single ndjson object into a write stream', function(t) {
    common.getDat(t, function(dat, done) {
@@ -648,6 +675,7 @@ module.exports.keepTotalRowCount = function(test, common) {

module.exports.all = function (test, common) {
  module.exports.blobWriteStream(test, common)
  module.exports.blobReadStream(test, common)
  module.exports.singleNdjsonObject(test, common)
  module.exports.singleNdjsonString(test, common)
  module.exports.multipleNdjsonObjects(test, common)