fix nextlink filter / redis cache key to include date start/end

backend/server.rb

@@ -108,10 +108,11 @@ def retrieveSensorData(params)
     date_end = params[:end]
 
     uri = "#{$base_url}/Things?$filter=name%20eq%20%27HLL_hl_device_#{id}%27&$expand=Datastreams($filter=contains(name,%27#{type}%27))"
+    cache_key = "#{uri}_#{date_start}_#{date_end}"
 
     body = nil
-    if($redis.exists uri)
-        body = $redis.get uri
+    if($redis.exists cache_key)
+        body = $redis.get cache_key
         puts "cache hit"
     else
     
@@ -136,7 +137,7 @@ def retrieveSensorData(params)
             {ds_names[index] => all_values.flatten}         
         }
         body = all_pages.to_json
-        $redis.set uri, body, {:ex => 3600} 
+        $redis.set cache_key, body, {:ex => 3600} 
     end
     body 
 end
@@ -147,7 +148,7 @@ def getPageRecursive(pages,uri,filter)
     response = RestClient.get uri
     page = JSON.parse(response)
     nextLink = page["@iot.nextLink"]
-    nextLink = nextLink + "&$select=phenomenonTime,result" if(filter)
+    nextLink = "#{nextLink}&$select=phenomenonTime,result" if(filter and nextLink != nil and not nextLink.empty?)
     pages << page
     getPageRecursive(pages,nextLink,filter) if (nextLink != nil and not nextLink.empty?)
 end