Updated APIGW mapping template

Author: jbnunn

README.md

@@ -33,7 +33,7 @@ Step 1 – Create an AWS CloudFormation stack with the [template](https://s3.ama
 
 Step 2 – Visit the [API Gateway dashboard](https://console.aws.amazon.com/apigateway/home) in your AWS account and create a new resource with a `/vote` endpoint. Assign a POST method that has the `Integration Request` type of "Lambda Function," and point to the Lambda function created by the AWS CloudFormation script that receives votes from your third-party voting service (in this example, Twilio).
 
-Under `Mapping Templates`, set the "Content-Type" to `application/x-www-form-urlencoded`, and add [this mapping template](apigateway-mappingtemplate.txt).
+Under `Body Mapping Templates`, set the "Content-Type" to `application/x-www-form-urlencoded`, and add [this mapping template](apigateway-mappingtemplate.txt).
 
 Step 3 – Visit the [Amazon Cognito dashboard](https://console.aws.amazon.com/cognito/home) and create a new identity pool that allows access to unauthenticated identities. Modify the policy document to allow read access to the aggregates DynamoDB table created by the AWS CloudFormation script above. This allows unauthenticated users to retrieve data from the vote aggregation table in DynamoDB. Amazon Cognito will provide sample code for the JavaScript platform. Note the value for identity pool ID; you'll need it in step 4.
 

apigateway-mappingtemplate.txt

@@ -1,41 +1,15 @@
-## convert HTML FORM POST data to JSON for insertion directly into a Lambda function
- 
-## get the raw post data from the AWS built-in variable and give it a nicer name
-#set($rawPostData = $input.path('$'))
- 
-## first we get the number of "&" in the string, this tells us if there is more than one key value pair
-#set($countAmpersands = $rawPostData.length() - $rawPostData.replace("&", "").length())
- 
-## if there are no "&" at all then we have only one key value pair.
-## we append an ampersand to the string so that we can tokenise it the same way as multiple kv pairs.
-## the "empty" kv pair to the right of the ampersand will be ignored anyway.
-#if ($countAmpersands == 0)
- #set($rawPostData = $rawPostData + "&")
-#end
- 
-## now we tokenise using the ampersand(s)
-#set($tokenisedAmpersand = $rawPostData.split("&"))
- 
-## we set up a variable to hold the valid key value pairs
-#set($tokenisedEquals = [])
- 
-## now we set up a loop to find the valid key value pairs, which must contain only one "="
-#foreach( $kvPair in $tokenisedAmpersand )
- #set($countEquals = $kvPair.length() - $kvPair.replace("=", "").length())
- #if ($countEquals == 1)
-  #set($kvTokenised = $kvPair.split("="))
-  #if ($kvTokenised[0].length() > 0)
-   ## we found a valid key value pair. add it to the list.
-   #set($devNull = $tokenisedEquals.add($kvPair))
-  #end
- #end
-#end
- 
-## next we set up our loop inside the output structure "{" and "}"
 {
-#foreach( $kvPair in $tokenisedEquals )
-  ## finally we output the JSON for this pair and append a comma if this isn't the last pair
-  #set($kvTokenised = $kvPair.split("="))
- "$kvTokenised[0]" : #if($kvTokenised[1].length() > 0)"$kvTokenised[1]"#{else}""#end#if( $foreach.hasNext ),#end
-#end
+        #foreach( $token in $input.path('$').split('&') )
+            #set( $keyVal = $token.split('=') )
+            #set( $keyValSize = $keyVal.size() )
+            #if( $keyValSize >= 1 )
+                #set( $key = $util.urlDecode($keyVal[0]) )
+                #if( $keyValSize >= 2 )
+                    #set( $val = $util.urlDecode($keyVal[1]) )
+                #else
+                    #set( $val = '' )
+                #end
+                "$key": "$val"#if($foreach.hasNext),#end
+            #end
+        #end
 }