I have an AWS Api Gateway set-up with an integration to an HTTP endpoint (specifically an AWS OpenSearch instance).

I want to transform the response from a query result from OpenSearch - effectively remove all unnecessary properties.

The response from a search from OpenSearch looks like this:

{
"took": 14,
"timed_out": false,
"_shards": {
    "total": 5,
    "successful": 5,
    "skipped": 0,
    "failed": 0
},
"hits": {
    "total": {
        "value": 4,
        "relation": "eq"
    },
    "max_score": 1,
    "hits": [
        {
            "_index": "drugs",
            "_type": "_doc",
            "_id": "5443",
            "_score": 1,
            "_source": {
                "name": "adderall",
                "med_id": "5443"
            }
        },
                    {
            "_index": "drugs",
            "_type": "_doc",
            "_id": "5444",
            "_score": 1,
            "_source": {
                "name": "adderall xr",
                "med_id": "5444"
            }
        }
    ]
  }
}

I want to transform that response with an Integration Mapping - returning only the

hits.hits[]._source.name

i.e.

{
    "adderall"
    "adderall xr"
}

I have a model defined in api gateway:

{
"$schema": "http://json-schema.org/draft-04/schema#",
"title": "SearchResultModel",
"type": "object",
"properties": {
    "hits": {
        "type": "object",
        "properties": {
            "hits": {
                "type": "array",
                "hits": {
                    "$ref": "#/definitions/hit"
                }
            }
        }
    }
},
"definitions": {
    "hit": {
        "type": "object",
        "properties": {
            "_index": {
                "type": "string"
            },
            "_type": {
                "type": "string"
            },
            "_id": {
                "type": "string"
            },
            "_score": {
                "type": "integer"
            },
            "_source": {
                "type": "object",
                "properties": {
                    "name": {
                        "type": "string"
                    },
                    "med_id": {
                        "type": "string"
                    }
                }
            }
        }
    }
  }
}

and the mapping template defined as:

#set($inputRoot = $input.path('$.hits'))
{
   #foreach($elem in $inputRoot.hits)
      "$elem._source.name"
   #if($foreach.hasNext),#end
   #end

 }

When I issue the request via post man - I am getting this result:

According to the docs and examples this should work.