src/Connector.js

@@ -351,13 +351,29 @@ module.exports = function (Y/* :any */) {
                 }
               })
               */
-              defer.resolve()
+              defer.resolve(m.os && m.os.length > 0)
             })
           } else if (message.type === 'sync done') {
             var self = this
-            this.connections[sender].syncStep2.then(function () {
+            this.connections[sender].syncStep2.then(function (resync) {
+              if (resync) {
+                const answer = {
+                  type: 'sync check',
+                }
+                for (const uid in self.connections) {
+                  if (uid !== sender) {
+                    self.send(uid, answer)
+                  }
+                }
+              }
               self._setSyncedWith(sender)
             })
+          } else if (message.type === 'sync check') {
+            const conn = this.connections[sender]
+            if (conn != null && conn.isSynced) {
+              conn.isSynced = false
+            }
+            this.findNextSyncTarget()
           } else if (message.type === 'update' && canWrite(auth)) {
             if (this.forwardToSyncingClients) {
               for (var client of this.syncingClients) {

src/Struct.js

@@ -165,7 +165,7 @@ module.exports = function (Y/* :any */) {
           o = (o.right == null) ? null : yield* this.getOperation(o.right)
         } else { // left == null
           parent = yield* this.getOperation(op.parent)
-          let startId = op.parentSub ? parent.map[op.parentSub] : parent.start
+          let startId = op.parentSub ? parent.map[op.parentSub] : (parent.struct == "Union" ? parent.union : parent.start)
           start = startId == null ? null : yield* this.getOperation(startId)
           o = start
         }
@@ -223,7 +223,7 @@ module.exports = function (Y/* :any */) {
           yield* this.setOperation(left)
         } else {
           // set op.right from parent, if necessary
-          op.right = op.parentSub ? parent.map[op.parentSub] || null : parent.start
+          op.right = op.parentSub ? parent.map[op.parentSub] || null : (parent.struct == "Union" ? parent.union : parent.start)
         }
         // reconnect right
         if (op.right != null) {
@@ -256,6 +256,11 @@ module.exports = function (Y/* :any */) {
           if (op.left != null) {
             yield* this.deleteOperation(op.id, 1, true)
           }
+        } else if (parent.struct == "Union") {
+          if (left == null) {
+            parent.union = op.id
+            yield* this.setOperation(parent)
+          }
         } else {
           if (right == null || left == null) {
             if (right == null) {

src/y.js

@@ -124,7 +124,7 @@ function Y (opts/* :YOptions */) /* :Promise<YConfig> */ {
     else if (opts.connector == null) reject('You must specify a connector! (missing connector property)')
     else if (opts.connector.name == null) reject('You must specify connector name! (missing connector.name property)')
     else if (opts.db == null) reject('You must specify a database! (missing db property)')
-    else if (opts.connector.name == null) reject('You must specify db name! (missing db.name property)')
+    else if (opts.db.name == null) reject('You must specify db name! (missing db.name property)')
     else {
       opts = Y.utils.copyObject(opts)
       opts.connector = Y.utils.copyObject(opts.connector)