I have the following document in mongo:
> { "_id": ObjectId("569afce4b932c542500143ec"),
> "date": "2016-1-17T2:31:0Z",
> "day": NumberInt(17),
> "model1": {
> "date": "2016-01-17T02:31+0000",
> "MondayModel": {
> "gtxdotdot": {
> "xdotdot": 0,
> "xdot": 0
> },
> "lsxdotdot": {
> "xdotdot": 0,
> "xdot": 0
> },
> "gtxdot": {
> "xdotdot": 0,
> "xdot": 0
> },
> "lsxdot": {
> "xdotdot": 0,
> "xdot": 0
> },
> "modeldotdot": {
> "mean": 0,
> "sdvar": 0
> },
> "modeldot": {
> "mean": 0,
> "sdvar": 0
> }
> }
> }
I wish to both find this document and extract only the values of model1.MondayModel.gtxdotdot.xdotdot/xdot/mean/sdvar
...
My current code does so with the following:
MongoCursor<Document> back = collection.find(and(eq("topic",topic),eq("sp",sp))).limit(1).iterator();
if (back.hasNext())
{
Document doc = back.next();
Document tmpddc1 = (Document)doc.get("model1");
Document tmpddc2 = (Document)tmpddc1.get("MondayModel");
Document tmpddc3 = (Document)tmpddc2.get("gtxdotdot");
gtxdotdotXdotdot = tmpddc3.getDouble("xdotdot");
gtxdotdotXdot = tmpddc3.getDouble("xdot");
tmpddc3 = (Document)tmpddc2.get("lsxdotdot");
lsxdotdotXdotdot = tmpddc3.getDouble("xdotdot");
lsxdotdotXdot = tmpddc3.getDouble("xdot");
tmpddc3 = (Document)tmpddc2.get("gtxdot");
gtxdotXdotdot = tmpddc3.getDouble("xdotdot");
gtxdotXdot = tmpddc3.getDouble("xdot");
tmpddc3 = (Document)tmpddc2.get("lsxdot");
lsxdotXdotdot = tmpddc3.getDouble("xdotdot");
lsxdotXdot = tmpddc3.getDouble("xdot");
tmpddc3 = (Document)tmpddc2.get("modeldotdot");
modeldotdotXmean = tmpddc3.getDouble("mean");
modeldotdotXsdvar = tmpddc3.getDouble("sdvar");
tmpddc3 = (Document)tmpddc2.get("modeldot");
modeldotXmean = tmpddc3.getDouble("mean");
modeldotXsdvar = tmpddc3.getDouble("sdvar");
}
Instead of running thought he document (as above) is there a way to get the values using the dot notation [model1.MondayModel.gtxdotdot.xdotdot]
? Something such as:
double value = doc.getDouble("model1.MondayModel.gtxdotdot.xdotdot");
I don't think you can use dot notation directly, but you can create your own helper function.
Solution 1: get field with dot notation
public static Object getWithDotNotation( Document document, String dots )
throws MongoException{
String[] keys = dots.split( "\\." );
Document doc = document;
for( int i = 0; i < keys.length - 1; i++ ){
Object o = doc.get( keys[ i ] );
if( o == null || !( o instanceof Document ) ){
throw new MongoException( String.format(
"Field '%s' does not exist or s not a Document", keys[ i ] ) );
}
doc = ( Document ) o;
}//end for
return doc.get( keys[ keys.length - 1 ] );
}
You can then use it like this:
String dotNotation = "model1.MondayModel.gtxdotdot.xdotdot";
FindIterable<Document> projection = mongoColl.find()
.projection( fields( include( dotNotation ) ) );
Double value = ( Double ) getWithDotNotation( projection.first(), dotNotation );
System.out.println( value ); // result: 0.0
This will simplify your code a whole lot. The only things to care for are:
try catch
blockgetWithDotNotation
might return nullSolution 2: flatten your doc
public static Document flattenDoc( Document document ){
Document flattened = new Document();
Queue<Pair<String, Document>> queue = new ArrayDeque<>();
queue.add( new Pair<>( "", document ) );
while( !queue.isEmpty() ){
Pair<String, Document> pair = queue.poll();
String key = pair.getKey();
for( Map.Entry<String, Object> entry : pair.getValue().entrySet() ){
if( entry.getValue() instanceof Document ){
queue.add( new Pair<>( key + entry.getKey() + ".", ( Document ) entry.getValue() ) );
}else{
flattened.put( key + entry.getKey(), entry.getValue() );
}
}//end for
}
return flattened;
}
With your sample data, the result of flattenDoc
is the following:
Document{{_id=569afce4b932c542500143ec,
date=2016-1-17T2:31:0Z,
day=17,
model1.date=2016-01-17T02:31+0000,
model1.MondayModel.gtxdotdot.xdotdot=0.0,
model1.MondayModel.gtxdotdot.xdot=0.0,
model1.MondayModel.lsxdotdot.xdotdot=0.0,
model1.MondayModel.lsxdotdot.xdot=0.0,
model1.MondayModel.gtxdot.xdotdot=0.0,
model1.MondayModel.gtxdot.xdot=0.0,
model1.MondayModel.lsxdot.xdotdot=0.0,
model1.MondayModel.lsxdot.xdot=0.0,
model1.MondayModel.modeldotdot.mean=0.0,
model1.MondayModel.modeldotdot.sdvar=0.0,
model1.MondayModel.modeldot.mean=0.0,
model1.MondayModel.modeldot.sdvar=0.0}}
So you can use getDouble("model1.MondayModel.gtxdotdot.xdotdot")
directly. This approach might be more efficient if you need to access all the fields.