You can now 'move' the first post of a topic to another topic as a merge. In that

case, the first post is cloned instead of being deleted from the original topic.

app/assets/javascripts/discourse/controllers/topic_controller.js

@@ -24,13 +24,12 @@ Discourse.TopicController = Discourse.ObjectController.extend(Discourse.Selected
 
   canMoveSelected: function() {
     if (!this.get('content.can_move_posts')) return false;
-    // For now, we can move it if we can delete it since the posts need to be deleted.
-    return this.get('canDeleteSelected');
+    return (this.get('selectedPostsCount') > 0);
   }.property('canDeleteSelected'),
 
   canDeleteSelected: function() {
     var selectedPosts = this.get('selectedPosts');
-    if (!(selectedPosts && selectedPosts.length > 0)) return false;
+    if (this.get('selectedPostsCount') === 0) return false;
 
     var canDelete = true;
     selectedPosts.each(function(p) {

app/models/topic.rb

@@ -462,7 +462,7 @@ class Topic < ActiveRecord::Base
     invite
   end
 
-  def move_posts_to_topic(post_ids, destination_topic)
+  def move_posts_to_topic(moved_by, post_ids, destination_topic)
     to_move = posts.where(id: post_ids).order(:created_at)
     raise Discourse::InvalidParameters.new(:post_ids) if to_move.blank?
 
@@ -472,11 +472,18 @@ class Topic < ActiveRecord::Base
       max_post_number = destination_topic.posts.maximum(:post_number) || 0
 
       to_move.each_with_index do |post, i|
-        first_post_number ||= post.post_number
-        row_count = Post.update_all ["post_number = :post_number, topic_id = :topic_id, sort_order = :post_number", post_number: max_post_number+i+1, topic_id: destination_topic.id], id: post.id, topic_id: id
-
-        # We raise an error if any of the posts can't be moved
-        raise Discourse::InvalidParameters.new(:post_ids) if row_count == 0
+        if post.post_number == 1
+          # We have a special case for the OP, we copy it instead of deleting it.
+          result = PostCreator.new(post.user,
+                                  raw: post.raw,
+                                  topic_id: destination_topic.id,
+                                  acting_user: moved_by).create
+        else
+          first_post_number ||= post.post_number
+          # Move the post and raise an error if it couldn't be moved
+          row_count = Post.update_all ["post_number = :post_number, topic_id = :topic_id, sort_order = :post_number", post_number: max_post_number+i+1, topic_id: destination_topic.id], id: post.id, topic_id: id
+          raise Discourse::InvalidParameters.new(:post_ids) if row_count == 0
+        end
       end
     end
 
@@ -493,7 +500,7 @@ class Topic < ActiveRecord::Base
       # If we're moving to a new topic...
       Topic.transaction do
         topic = Topic.create(user: moved_by, title: opts[:title], category: category)
-        first_post_number = move_posts_to_topic(post_ids, topic)
+        first_post_number = move_posts_to_topic(moved_by, post_ids, topic)
       end
 
     elsif opts[:destination_topic_id].present?
@@ -501,7 +508,7 @@ class Topic < ActiveRecord::Base
 
       topic = Topic.where(id: opts[:destination_topic_id]).first
       Guardian.new(moved_by).ensure_can_see!(topic)
-      first_post_number = move_posts_to_topic(post_ids, topic)
+      first_post_number = move_posts_to_topic(moved_by, post_ids, topic)
 
     end
 

lib/post_creator.rb

@@ -11,6 +11,9 @@ class PostCreator
   #   raw                     - raw text of post
   #   image_sizes             - We can pass a list of the sizes of images in the post as a shortcut.
   #   invalidate_oneboxes     - Whether to force invalidation of oneboxes in this post
+  #   acting_user             - The user performing the action might be different than the user
+  #                             who is the post "author." For example when copying posts to a new
+  #                             topic.
   #
   #   When replying to a topic:
   #     topic_id              - topic we're replying to
@@ -89,6 +92,7 @@ class PostCreator
       post.post_type = @opts[:post_type] if @opts[:post_type].present?
       post.no_bump = @opts[:no_bump] if @opts[:no_bump].present?
       post.extract_quoted_post_numbers
+      post.acting_user = @opts[:acting_user] if @opts[:acting_user].present?
 
       post.image_sizes = @opts[:image_sizes] if @opts[:image_sizes].present?
       post.invalidate_oneboxes = @opts[:invalidate_oneboxes] if @opts[:invalidate_oneboxes].present?

spec/models/topic_spec.rb

@@ -221,8 +221,8 @@ describe Topic do
 
       it "enqueues a job to notify users" do
         topic.stubs(:add_moderator_post)
-        Jobs.expects(:enqueue).with(:notify_moved_posts, post_ids: [p1.id, p4.id], moved_by_id: user.id)
-        topic.move_posts(user, [p1.id, p4.id], title: "new testing topic name")
+        Jobs.expects(:enqueue).with(:notify_moved_posts, post_ids: [p2.id, p4.id], moved_by_id: user.id)
+        topic.move_posts(user, [p2.id, p4.id], title: "new testing topic name")
       end
 
       it "adds a moderator post at the location of the first moved post" do
@@ -253,7 +253,7 @@ describe Topic do
       context "to a new topic" do
         let!(:new_topic) { topic.move_posts(user, [p2.id, p4.id], title: "new testing topic name") }
 
-        it "moved correctly" do
+        it "works correctly" do
           TopicUser.where(user_id: user.id, topic_id: topic.id).first.last_read_post_number.should == p3.post_number
 
           new_topic.should be_present
@@ -290,7 +290,7 @@ describe Topic do
         let!(:destination_op) { Fabricate(:post, topic: destination_topic, user: user) }
         let!(:moved_to) { topic.move_posts(user, [p2.id, p4.id], destination_topic_id: destination_topic.id )}
 
-        it "moved correctly" do
+        it "works correctly" do
           moved_to.should == destination_topic
 
           # Check out new topic
@@ -305,10 +305,12 @@ describe Topic do
           p2.reload
           p2.sort_order.should == 2
           p2.post_number.should == 2
+          p2.topic_id.should == moved_to.id
 
           p4.reload
           p4.post_number.should == 3
           p4.sort_order.should == 3
+          p4.topic_id.should == moved_to.id
 
           # Check out the original topic
           topic.reload
@@ -323,9 +325,40 @@ describe Topic do
           # Should update last reads
           TopicUser.where(user_id: user.id, topic_id: topic.id).first.last_read_post_number.should == p3.post_number
         end
+      end
+
+      context "moving the first post" do
+
+        let!(:new_topic) { topic.move_posts(user, [p1.id, p2.id], title: "new testing topic name") }
+
+        it "copies the OP, doesn't delete it" do
+          new_topic.should be_present
+          new_topic.posts.first.raw.should == p1.raw
+
+          new_topic.reload
+          new_topic.posts_count.should == 2
+          new_topic.highest_post_number.should == 2
+
+          # First post didn't move
+          p1.reload
+          p1.sort_order.should == 1
+          p1.post_number.should == 1
+          p1.topic_id == topic.id
+
+          # Second post is in a new topic
+          p2.reload
+          p2.post_number.should == 2
+          p2.sort_order.should == 2
+          p2.topic_id == new_topic.id
+
+          topic.reload
+          topic.posts.should =~ [p1, p3, p4]
+          topic.highest_post_number.should == p4.post_number
+        end
 
       end
 
+
     end
   end