Not able to pass params POST to AWS Lambda from Amazon API Gateway

Question

I have been trying to pass a query string or route parameter to AWS Lambda from Amazon API Gateway.
I mapped the query string params to AWS Lambda using the API Gateway, using POST Values instead of query-string
Like this : 

{
    "values": "$input.params()"
}

It doesn't seem to be working, does not display any actual form of data.
I am posted it using : 

application/x-www-form-urlencoded

I got my response from my lambda function because of it no doubt it is invoking lambda fine but the main problem here is that I don't get see the POST params anywhere. I am not able to figure out how to map them. I dumped and as a return, what I get on Lambda side is here:

{"values":"{path={}, querystring={}, header={Accept=*/*, Accept-Encoding=gzip, deflate, Accept-Language=en-US,en;q=0.8, Cache-Control=no-cache, CloudFront-Forwarded-Proto=https, CloudFront-Is-Desktop-Viewer=true, CloudFront-Is-Mobile-Viewer=false, CloudFront-Is-SmartTV-Viewer=false, CloudFront-Is-Tablet-Viewer=false, CloudFront-Viewer-Country=US, Content-Type=application/x-www-form-urlencoded, Origin=chrome-extension://fhbjgbiflinjbdggehcddcbncdddomop, Postman-Token=7ba28698-8753-fcb1-1f48-66750ce12ade, Via=1.1 6ba5553fa41dafcdc0e74d152f3a7a75.cloudfront.net (CloudFront), X-Amz-Cf-Id=sc8C7dLcW0BHYopztNYrnddC0hXyFdBzHv0O9aWU1gKhd1D_J2HF3w==, X-Forwarded-For=50.196.93.57, 54.239.140.62, X-Forwarded-Port=443, X-Forwarded-Proto=https}}"

Answer 1

For this template :

application/x-www-form-urlencoded 

This line below will be work for all the cases:

{
    "data": {
        #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
    }
}

This will transform an input of: 

name=Marcus&email=email%40example.com&message=

into

{
    "data": {
                "name": "Marcus",
                "email": "email@example.com",
                "message": ""
    }
}

In Lambda handler one can use it like this as it returns all input data:

module.exports.handler = function(event, context, cb) {
  return cb(null, {
    data: event.data
  });
};

Answer 2

All you need to do is check, "Use Lambda Proxy integration", under Integration Request, under the resource.

You'll then be able to access query parameters, path parameters and headers like so

event['pathParameters']['param1']
event["queryStringParameters"]['queryparam1']
event['requestContext']['identity']['userAgent']
event['requestContext']['identity']['sourceIP']

Answer 3

This also works well

The steps to get this working are:

Within the API Gateway Console ...

1. go to Resources -> Integration Request
2. click on the plus or edit icon next to templates dropdown (odd I know since the template field is already open and the button here looks greyed out)
3. Explicitly type application/json in the content-type field even though it shows a default (if you don't do this it will not save and will not give you an error message)

4. put this in the input mapping { "name": "$input.params('name')" }

5. click on the check box next to the templates dropdown (I'm assuming this is what finally saves it)