Store gallery photo names in datasets for easier iterating

_plugins/assign_page.rb

@@ -0,0 +1,30 @@
+# adapted from
+# - https://gist.githubusercontent.com/nathangrigg/7387238/raw/fdb229fb162a303cbd9a666de8be7d0aa3515cd6/assign_page.rb
+module Jekyll
+  module Tags
+    class AssignPage < Liquid::Assign
+      TrailingIndex = /index\.html$/
+
+      def page_hash(context)
+        reg = context.registers
+        site = reg[:site]
+        if reg[:page_hash].nil?
+          reg[:page_hash] = Hash[(site.posts.docs + site.pages).collect {
+            |x| [x.url.sub(TrailingIndex, ''), x]}]
+        end
+        return reg[:page_hash]
+      end
+
+      # Assign's Initializer stores variable name in @to and the value in @from.
+      def render(context)
+        url = @from.render(context)
+        page = page_hash(context)[url.sub(TrailingIndex, '')]
+        raise ArgumentError.new "No page with url #{url}." if page.nil?
+        context.scopes.last[@to] = page
+        return
+      end
+    end
+  end
+end
+
+Liquid::Template.register_tag('assign_page', Jekyll::Tags::AssignPage)