#3: Routet page and limited entries

The blog module routes /blog/{page} and the blog handler limits the entries per page (given as a feature) and sets the offsets according to the given page number

examples/demo/modules/blog/cms_blog_api.e

@@ -49,4 +49,10 @@ feature -- Access node
 			Result := node_storage.blogs
 		end
 
+	blogs_order_created_desc_limited (a_limit:INTEGER_32; a_offset:INTEGER_32) : LIST[CMS_NODE]
+			-- List of nodes ordered by creation date and limited by limit and offset
+		do
+			Result := node_storage.blogs_limited (a_limit, a_offset)
+		end
+
 end

examples/demo/modules/blog/cms_blog_module.e

@@ -106,14 +106,6 @@ feature -- Access: router
 		end
 
 
---feature -- Access: router
-
-	--setup_router (a_router: WSF_ROUTER; a_api: CMS_API)
-			-- <Precursor>
-	--	do
-	--		a_router.handle_with_request_methods ("/blogs/", create {WSF_URI_AGENT_HANDLER}.make (agent handle_blogs (?,?, a_api)), a_router.methods_get)
-	--	end
-
 configure_web (a_api: CMS_API; a_node_api: CMS_BLOG_API; a_router: WSF_ROUTER)
 		local
 			l_blog_handler: BLOG_HANDLER
@@ -121,8 +113,14 @@ configure_web (a_api: CMS_API; a_node_api: CMS_BLOG_API; a_router: WSF_ROUTER)
 		do
 			-- TODO: for now, focused only on web interface, add REST api later. [2015-May-18]
 			create l_blog_handler.make (a_api, a_node_api)
-			create l_uri_mapping.make_trailing_slash_ignored ("/blogs", l_blog_handler)
+
+			-- Let the class BLOG_HANDLER handle the requests on "/blogs"
+			create l_uri_mapping.make_trailing_slash_ignored("/blogs", l_blog_handler)
 			a_router.map_with_request_methods (l_uri_mapping, a_router.methods_get)
+
+			-- We can add a page number after /blogs/ to get older posts
+			a_router.handle_with_request_methods ("/blogs/{page}", l_blog_handler, a_router.methods_get)
+
 		end
 
 feature -- Hooks
@@ -136,6 +134,7 @@ feature -- Hooks
 		local
 			lnk: CMS_LOCAL_LINK
 		do
+			-- Add the link to the blog to the main menu
 			create lnk.make ("Blogs", "/blogs/")
 			a_menu_system.primary_menu.extend (lnk)
 		end

examples/demo/modules/blog/handler/blog_handler.e

@@ -12,9 +12,18 @@ inherit
 
 	WSF_URI_HANDLER
 		rename
+			execute as uri_execute,
 			new_mapping as new_uri_mapping
 		end
 
+	WSF_URI_TEMPLATE_HANDLER
+		rename
+			execute as uri_template_execute,
+			new_mapping as new_uri_template_mapping
+		select
+			new_uri_template_mapping
+		end
+
 	WSF_RESOURCE_HANDLER_HELPER
 		redefine
 			do_get
@@ -33,6 +42,18 @@ feature -- execute
 			execute_methods (req, res)
 		end
 
+	uri_execute (req: WSF_REQUEST; res: WSF_RESPONSE)
+			-- Execute request handler
+		do
+			execute (req, res)
+		end
+
+	uri_template_execute (req: WSF_REQUEST; res: WSF_RESPONSE)
+			-- Execute request handler
+		do
+			execute (req, res)
+		end
+
 feature -- Settings
 	entries_per_page : INTEGER
 		-- The numbers of posts that are shown on one page. If there are more post a pagination is generated
@@ -42,27 +63,54 @@ feature -- Settings
 			Result := 2
 		end
 
+	more_than_one_page : BOOLEAN
+		-- Checks if all posts fit on one page (FALSE) or if more than one page is needed (TRUE)
+		do
+			Result := entries_per_page < node_api.blogs_count
+		end
+
 feature -- HTTP Methods	
 	do_get (req: WSF_REQUEST; res: WSF_RESPONSE)
 			-- <Precursor>
 		local
 			l_page: CMS_RESPONSE
+			l_posts: LIST[CMS_NODE]
 			s: STRING
 			n: CMS_NODE
 			lnk: CMS_LOCAL_LINK
 			hdate: HTTP_DATE
+			page_number:NATURAL_16
 		do
 				-- At the moment the template is hardcoded, but we can
 				-- get them from the configuration file and load them into
 				-- the setup class.
 
+			--Check if a page is given, if not start with page 1
+			if req.path_info.ends_with_general ("/blogs") then
+				-- No page number given, set to 0
+				page_number := 1
+			else
+				-- Read page number from get variable
+				page_number := page_number_path_parameter (req)
+			end
+
+			-- Ensure that page is never 0 (happens if /blogs/ is routed)
+			if page_number = 0 then page_number := 1 end
+
 			create {GENERIC_VIEW_CMS_RESPONSE} l_page.make (req, res, api)
 			l_page.add_variable (node_api.nodes, "nodes")
 
 
-				-- NOTE: for development purposes we have the following hardcode output.
-			create s.make_from_string ("<h2>Blog</h2>")
-			if attached node_api.blogs_order_created_desc as lst then
+			-- Output the title. If more than one page, also output the current page number
+			create s.make_from_string ("<h2>Blog")
+			if more_than_one_page then
+				s.append (" (Page " + page_number.out + ")")
+				-- Get the posts from the current page (limited by entries per page)
+			end
+			s.append ("</h2>")
+
+
+			if attached node_api.blogs_order_created_desc_limited (entries_per_page, (page_number-1) * entries_per_page) as lst then
 				-- Filter out blog entries from all nodes
 				--if n.content_type.is_equal ("blog") then
 					s.append ("<ul class=%"cms-blog-nodes%">%N")
@@ -113,5 +161,19 @@ feature -- HTTP Methods
 			l_page.execute
 		end
 
+feature -- Query
+
+	page_number_path_parameter (req: WSF_REQUEST): NATURAL_16
+			-- Returns the page number from the path /blogs/{page}. It's an unsigned integere since negative pages are not allowed
+		local
+			s: STRING
+		do
+			if attached {WSF_STRING} req.path_parameter ("page") as p_page then
+				s := p_page.value
+				if s.is_natural_16 then
+					Result := s.to_natural_16
+				end
+			end
+		end
 
 end

examples/demo/modules/blog/persistence/cms_blog_storage_i.e

@@ -21,4 +21,9 @@ feature -- Access
 		deferred
 		end
 
+	blogs_limited (limit:INTEGER_32; offset:INTEGER_32) : LIST[CMS_NODE]
+			-- List of nodes ordered by creation date from limit to limit + offset
+		deferred
+		end
+
 end

examples/demo/modules/blog/persistence/cms_blog_storage_null.e

@@ -28,4 +28,9 @@ feature -- Access
 			create {ARRAYED_LIST [CMS_NODE]} Result.make (0)
 		end
 
+	blogs_limited (limit:INTEGER_32; offset:INTEGER_32) : LIST[CMS_NODE]
+			-- List of nodes ordered by creation date from limit to limit + offset
+		do
+			create {ARRAYED_LIST [CMS_NODE]} Result.make (0)
+		end
 end

examples/demo/modules/blog/persistence/cms_blog_storage_sql.e

@@ -49,6 +49,32 @@ feature -- Access
 			end
 		end
 
+	blogs_limited (a_limit:INTEGER_32; a_offset:INTEGER_32) : LIST[CMS_NODE]
+			-- List of nodes ordered by creation date from limit to limit + offset
+		local
+			l_parameters: STRING_TABLE [detachable ANY]
+		do
+			create {ARRAYED_LIST [CMS_NODE]} Result.make (0)
+
+			error_handler.reset
+			write_information_log (generator + ".nodes")
+
+			from
+				create l_parameters.make (2)
+				l_parameters.put (a_limit, "limit")
+				l_parameters.put (a_offset, "offset")
+				sql_query (sql_blogs_limited, l_parameters)
+				sql_start
+			until
+				sql_after
+			loop
+				if attached fetch_node as l_node then
+					Result.force (l_node)
+				end
+				sql_forth
+			end
+		end
+
 feature {NONE} -- Queries
 
 	sql_select_blog_count: STRING = "SELECT count(*) FROM Nodes WHERE status != -1 AND type = %"blog%";"
@@ -58,4 +84,7 @@ feature {NONE} -- Queries
 	sql_select_blogs_order_created_desc: STRING = "SELECT * FROM Nodes WHERE status != -1 AND type = %"blog%" ORDER BY created DESC;"
 			-- SQL Query to retrieve all nodes that are from the type "blog" ordered by descending creation date.
 
+	sql_blogs_limited: STRING = "SELECT * FROM Nodes WHERE status != -1 AND type = %"blog%" ORDER BY created DESC LIMIT :limit OFFSET :offset ;"
+			--- SQL Query to retrieve all node of type "blog" from limit to limit + offset
+
 end