added method to model before create

app/controllers/admin/import_controller.rb

@@ -231,7 +231,6 @@ class Admin::ImportController < OrbitAdminController
             page_id = page_id + "_" + (number + 1).to_s
           end
           p = Page.new(:page_id => page_id, :parent_page_id => Page.root.id, :page_type => "page", :url => "/#{page_id}", :module => "page_content", :enabled_for => ["en", "zh_tw"], :menu_enabled_for => ["en", "zh_tw"], :enabled_for_sitemap => ["en","zh_tw"], :name_translations => {"en"=>page["title"]["en"], "zh_tw" => page["title"]["zh_tw"]},:rss2_id => page["page_id"])
-          p.number = Page.root.child_page.max(:number) + 1
           p.save
           en = smart_downloader(page["content"]["en"],data["site_url"])
           zh_tw = smart_downloader(page["content"]["zh_tw"],data["site_url"])
@@ -254,7 +253,6 @@ class Admin::ImportController < OrbitAdminController
               case childpage["type"]
               when "page"
                 cp = Page.new(:page_id => p_id, :parent_page_id => p.id, :page_type => "page", :url => "/#{p.page_id}/#{p_id}", :module => "page_content", "enabled_for" => ["en", "zh_tw"], :menu_enabled_for => ["en", "zh_tw"], :enabled_for_sitemap => ["en","zh_tw"], :name_translations => {"en"=>childpage["title"]["en"], "zh_tw" => childpage["title"]["zh_tw"]},:rss2_id => childpage["page_id"])
-                cp.number = p.child_page.max(:number) + 1
                 cp.save
                 en = smart_downloader(childpage["content"]["en"],data["site_url"])
                 zh_tw = smart_downloader(childpage["content"]["zh_tw"],data["site_url"])
@@ -262,7 +260,6 @@ class Admin::ImportController < OrbitAdminController
                 page_context.save
               when "exturl"
                 cp = Page.new(:page_id => p_id, :parent_page_id => p.id, :page_type => "link", "url" => "/#{p.page_id}/#{p_id}", :enabled_for => ["en", "zh_tw"], :menu_enabled_for => ["en", "zh_tw"], :enabled_for_sitemap => ["en","zh_tw"], :name_translations => {"en"=>childpage["title"]["en"], "zh_tw" => childpage["title"]["zh_tw"]}, :external_url_translations => {"en" => childpage["url"], "zh_tw" => childpage["url"]},:rss2_id => childpage["page_id"])
-                cp.number = p.child_page.max(:number) + 1
                 cp.save
               when "file"
                 asset = Asset.new
@@ -273,7 +270,6 @@ class Admin::ImportController < OrbitAdminController
                 @user.save
                 external_url = asset.data.url
                 cp = Page.new(:page_id => p_id, :parent_page_id => p.id, :page_type => "link", "url" => "/#{p.page_id}/#{p_id}", :enabled_for => ["en", "zh_tw"], :menu_enabled_for => ["en", "zh_tw"], :enabled_for_sitemap => ["en","zh_tw"], :name_translations => {"en"=>childpage["title"]["en"], "zh_tw" => childpage["title"]["zh_tw"]}, :external_url_translations => {"en" => external_url, "zh_tw" => external_url},:rss2_id => childpage["page_id"])
-                cp.number = p.child_page.max(:number) + 1
                 cp.save
               end
             end

app/controllers/pages_controller.rb

@@ -320,7 +320,6 @@ class PagesController < ApplicationController
       p["external_url_translations"]["en"] = p["external_url_translations"]["en"].sub("http://" + request.host_with_port,"")
       p["external_url_translations"]["zh_tw"] = p["external_url_translations"]["zh_tw"].sub("http://" + request.host_with_port,"")
     end
-    p[:number] = page.child_page.max(:number) + 1
     p
   end
 

app/models/page.rb

@@ -27,6 +27,18 @@ class Page
 	has_many :child_page, :class_name => 'Page', :inverse_of => :parent_page, :dependent => :destroy
 	belongs_to :parent_page, :class_name => 'Page', :inverse_of => :child_page
 
+	before_create :assign_page_number
+
+	def assign_page_number
+		parent_page = self.parent_page
+		if parent_page.child_page.count == 0
+			number = 0
+		else
+			number = parent_page.child_page.max(:number) + 1
+		end
+		self.number = number
+	end
+
 	def to_param
 		page_id.parameterize
 	end