Parent/Child Mapping example of a Document meta-data record and it's child file content

gistfile1.sh

export ES_HOST=http://localhost:9200

# delete & recreate index with defaults
curl -XDELETE $ES_HOST/projects
curl -XPUT $ES_HOST/projects 

# configure the Parent mapping type, a 'doc' with a document number and title field to simulate common meta data
curl -XPUT $ES_HOST/projects/doc/_mapping -d'
{
  "doc": {
      "properties": {
        "docno": {"type": "string"},
        "title": {"type": "string"}
      }
  }
}
'

# now create the Child mapping, a type called 'filecontent' to express the physical content of a file that is attached to a Meta-Data record (the parent)
curl -XPUT $ES_HOST/projects/filecontent/_mapping -d'
{
   "filecontent": {
      "_parent" : { "type": "doc"},
      "properties" : {
         "content" : {"type": "string"}
      }
   }
}
'


# Index a single document meta-data record
curl -X PUT $ES_HOST/projects/doc/1 -d '
{
   "docno" : "ABC-123",
   "title" : "Secret Nuclear Power Plant Control Systems"
}'


# Index a single file's content, attaching it to it's parent type by the parent ID (at least that's what I'm after/interpretting it as ...)
curl -X PUT $ES_HOST/projects/filecontent/1?parent=1 -d '
{
   "content" : "When you press the red button, things go bang!"
}'


# I would like to be able to search on the 'filecontent' type but get results 
# of the parent, this query is cut/paste from the top_children example, but I'm getting an error
# I'm almost sure I've got the idea of the query wrong, but I'm hoping 
# this gist explains the intent I'm trying to do
curl -X GET $ES_HOST/projects/doc/_search?pretty=true -d '
{
  "query": {
    "top_children" : {
        "type": "filecontent",
        "query" : {
            "term" : {
                "content" : "red"
            }
        }
        "score" : "max",
        "factor" : 5,
        "incremental_factor" : 2
    }
 }
}'