Add functionality to copy feed and append to it.

Author: bettori

index.js

@@ -1,6 +1,7 @@
 var level = require('level')
 var hypercore = require('hypercore')
 var createImportPipeline = require('./lib/import.js')
+var feedOperations = require('./lib/feedOperations.js')
 
 module.exports = Jawn
 
@@ -14,3 +15,8 @@ function Jawn (opts) {
 Jawn.prototype.createImportPipeline = function (opts) {
   return createImportPipeline(this, opts)
 }
+
+Jawn.prototype.createAppendableFeed = function (feedId, data) {
+  var feed = feedOperations.appendableFeed(this.core, feedId)
+  return feed
+}

lib/feedOperations.js

@@ -0,0 +1,50 @@
+
+module.exports = {
+  appendableFeed
+}
+
+function appendableFeed (core, feedId) {
+  var refFeed = core.get(feedId)
+  var newFeed = core.add()
+  var blockNumber = 0
+
+  var copyOriginal = function (resolve, reject) {
+    for (var i = 0; i < refFeed.blocks; i++) {
+      refFeed.get(i, function (err, block) {
+        if (err) {
+          console.log(err)
+          reject()
+        }
+
+        newFeed.append(block, function () {
+          blockNumber++
+          console.log('Copying block ' + blockNumber + '/' + newFeed.blocks + ' from original feed')
+
+          if (blockNumber === refFeed.blocks) {
+            resolve()
+          }
+        })
+      })
+    }
+  }
+
+  newFeed.append_p = function (data) {
+    return new Promise(function (resolve, reject) {
+      newFeed.append(data, resolve)
+    })
+  }
+
+  newFeed.finalize_p = function () {
+    return new Promise(function (resolve, reject) {
+      newFeed.finalize(resolve)
+    })
+  }
+
+  newFeed.initialize = function () {
+    return new Promise(function (resolve, reject) {
+      copyOriginal(resolve, reject)
+    })
+  }
+
+  return newFeed
+}

test/feedOperations.js

@@ -0,0 +1,103 @@
+var test = require('tape')
+var Jawn = require('../')
+var memdb = require('memdb')
+var feedOps = require('../lib/feedOperations.js')
+
+test('appendable feed', function (t) {
+  var jawn = freshJawn()
+  var feed = jawn.core.add()
+
+  feed.pappend = function (data) {
+    return new Promise(function (resolve, reject) {
+      feed.append(data, resolve)
+    })
+  }
+
+  feed.pfinalize = function () {
+    return new Promise(function (resolve, reject) {
+      feed.finalize(resolve)
+    })
+  }
+
+  feed.pappend('hello').then(function () {
+    console.log('Appended')
+    return feed
+  })
+  .then(function (feed) {
+    return feed.pfinalize()
+  })
+  .then(function () {
+    console.log('Finalized with id ' + feed.id.toString('hex'))
+    var appfeed = feedOps.appendableFeed(jawn.core, feed.id)
+    appfeed.initialize().then(function () {
+      return appfeed.finalize_p()
+    })
+    .then(function () {
+      t.same(appfeed.blocks, feed.blocks, 'testing')
+      t.end()
+    })
+  })
+})
+
+test('append to feed', function (t) {
+  var jawn = freshJawn()
+  var feed = jawn.core.add()
+  var expected = ['hello', 'there', 'goodbye']
+
+  storeDataInFeed(feed, ['hello', 'there'])
+  .then(function () {
+    console.log('Finalized with id ' + feed.id.toString('hex'))
+
+    var appfeed = feedOps.appendableFeed(jawn.core, feed.id)
+
+    appfeed.initialize().then(function () {
+      return appfeed.append_p('goodbye')
+    })
+    .then(function () {
+      return appfeed.finalize_p()
+    })
+    .then(function () {
+      t.same(appfeed.blocks, expected.length, 'Correct number of blocks')
+      for (var i = 0; i < appfeed.blocks; i++) {
+        appfeed.get(i, function (err, block) {
+          if (err) {
+            console.log(err)
+          }
+          t.same(block.toString(), expected.shift(), 'Feed block match')
+          if (expected.length === 0) {
+            t.end()
+          }
+        })
+      }
+    })
+  })
+})
+
+function storeDataInFeed (feed, data) {
+  feed.pappend = function (data) {
+    return new Promise(function (resolve, reject) {
+      feed.append(data, resolve)
+    })
+  }
+
+  feed.pfinalize = function () {
+    return new Promise(function (resolve, reject) {
+      feed.finalize(resolve)
+    })
+  }
+
+  return new Promise(function (resolve, reject) {
+    feed.pappend(data).then(function () {
+      console.log('Appended')
+      return feed
+    })
+    .then(function (feed) {
+      return feed.pfinalize()
+    })
+    .then(resolve)
+  })
+}
+
+function freshJawn () {
+  return new Jawn({db: memdb()})
+}

test/import.js

@@ -30,7 +30,7 @@ test('import json to jawn', function (t) {
 test('import csv to jawn', function (t) {
   var jawn = freshJawn()
   importFromFile(jawn, 'sample.csv', {'format': 'csv'})
-  var importStream = importFromFile(jawn, 'sample.csv', {'format': 'csv'}, verify)
+  var importStream = importFromFile(jawn, 'sample.csv', {'format': 'csv'})
   var expected = [
     '{"Type of Experience":"Writing software in any programming language","Little/No Experience":"1","Some Experience":"5","Very Familiar":"4"}',
     '{"Type of Experience":"Frontend Web Development","Little/No Experience":"4","Some Experience":"3","Very Familiar":"3"}',