save users into new `user` collection

flattenUser.js

@@ -18,10 +18,10 @@ function createConnection(URI) {
   });
 }
 
-function createQuery(db, collection, selection, options, batchSize) {
+function createQuery(db, collection, options, batchSize) {
   return Rx.Observable.create(function (observer) {
     console.log('Creating cursor...');
-    var cursor = db.collection(collection).find(selection, options);
+    var cursor = db.collection(collection).find({}, options);
     cursor.batchSize(batchSize || 20);
     // Cursor.each will yield all doc from a batch in the same tick,
     // or schedule getting next batch on nextTick
@@ -42,9 +42,9 @@ function createQuery(db, collection, selection, options, batchSize) {
   });
 }
 
-function saveUser(user) {
+function insertMany(db, collection, users, options) {
   return Rx.Observable.create(function(observer) {
-    user.save(function(err) {
+    db.collection(collection).insertMany(users, options, function(err) {
       if (err) {
         return observer.onError(err);
       }
@@ -54,21 +54,36 @@ function saveUser(user) {
 }
 
 var count = 0;
-createConnection(secrets.db)
+// will supply our db object
+var dbObservable = createConnection(secrets.db).shareReplay();
+dbObservable
   .flatMap(function(db) {
+    // returns user document, n users per loop where n is the batchsize.
     return createQuery(db, 'users', {});
   })
   .map(function(user) {
+    // flatten user
     assign(user, user.portfolio, user.profile);
     return user;
   })
-  .flatMap(function(user) {
-    return saveUser(user);
+  // batch them into arrays of twenty documents
+  .bufferWithCount(20)
+  // get bd object ready for insert
+  .withLatestFrom(dbObservable, function(users, db) {
+    return {
+      users: users,
+      db: db
+    };
   })
+  .flatMap(function(dats) {
+    // bulk insert into new collection for loopback
+    return insertMany(dats.db, 'user', dats.users, { w: 1 });
+  })
+  // count how many times insert completes
   .count()
   .subscribe(
     function(_count) {
-      count = _count;
+      count = _count * 20;
     },
     function(err) {
       console.log('an error occured', err);