reducing doc.fields into an array using map keys

bulk_docs.json

{
	"all_or_nothing": true,
	"docs": [
		{
			"_id": "doc1",
			"device_id": "wub"
		},
		{
			"_id": "doc2",
			"device_id": "wub"
		},
		{
			"_id": "doc3",
			"device_id": "wib"
		},
                {
			"_id": "doc4",
			"device_id": "wib"
		}
	]
}

map_reduce.js

// put this in a wubble ddoc, in a view called wibble

// map
function(doc) {
    if (doc.device_id) {
        emit(doc.device_id, doc._id);
    }
}


// reduce

function(key, array) {
    var index = array.indexOf(key);
    if (!index) {
        array.push(key)
    }
    return (key, array.sort())
}

view_no_reduce.json

dave@akai /tmp % pie get $DB/_design/wubble/_view/wibble\?reduce\=false                                                                                                                                        
GET /testy/_design/wubble/_view/wibble HTTP/1.1
Host: localhost:5984
Content-Type: application/json; charset=utf-8
Accept-Encoding: identity, deflate, compress, gzip
Accept: application/json
User-Agent: HTTPie/0.2.2dev

{}

HTTP/1.1 200 OK
Transfer-Encoding: chunked
Server: CouchDB/1.3.0a- (Erlang OTP/R15B01)
ETag: "EK98LDWM1RZ5OOLNDK0I4V4FS"
Date: Mon, 25 Jun 2012 13:12:58 GMT
Content-Type: application/json
Cache-Control: must-revalidate

{
    "offset": 0, 
    "rows": [
        {
            "id": "doc3", 
            "key": "wib", 
            "value": "doc3"
        }, 
        {
            "id": "doc4", 
            "key": "wib", 
            "value": "doc4"
        }, 
        {
            "id": "doc1", 
            "key": "wub", 
            "value": "doc1"
        }, 
        {
            "id": "doc2", 
            "key": "wub", 
            "value": "doc2"
        }
    ], 
    "total_rows": 4
}

view_reduce.json

dave@akai /tmp % pie get $DB/_design/wubble/_view/wibble\?group\=true                                                                                                                                          
GET /testy/_design/wubble/_view/wibble HTTP/1.1
Host: localhost:5984
Content-Type: application/json; charset=utf-8
Accept-Encoding: identity, deflate, compress, gzip
Accept: application/json
User-Agent: HTTPie/0.2.2dev

{}

HTTP/1.1 200 OK
Transfer-Encoding: chunked
Server: CouchDB/1.3.0a- (Erlang OTP/R15B01)
ETag: "7Q5NK7Q2R994UP0SAEDAK9G4R"
Date: Mon, 25 Jun 2012 13:14:09 GMT
Content-Type: application/json
Cache-Control: must-revalidate

{
    "rows": [
        {
            "key": "wib", 
            "value": [
                "doc3", 
                "doc4"
            ]
        }, 
        {
            "key": "wub", 
            "value": [
                "doc1", 
                "doc2"
            ]
        }
    ]
}

view_results.json

{
    "offset": 0, 
    "rows": [
        {
            "id": "doc1", 
            "key": "wub", 
            "value": "doc1"
        }, 
        {
            "id": "doc2", 
            "key": "wub", 
            "value": "doc2"
        }, 
         {
            "id": "doc3", 
            "key": "wib", 
            "value": "doc3"
        }, 
         {
            "id": "doc4", 
            "key": "wib", 
            "value": "doc4"
        }
	],
    "total_rows": 4
}