I have following document structure (This is dummy document for understanding purpose)
{
"id" : "p1245",
"Info" : [
{
"cloth_name" : "ABC",
"cloth_type" : "C"
},
{
"cloth_name" : "PQR",
"cloth_type" : "J"
},
{
"cloth_name" : "SAM",
"cloth_type" : "T"
}
]
},
{
"id" : "p124576",
"Info" : [
{
"cloth_name" : "HTC",
"cloth_type" : "C"
}
]
}
From these document I want to project the "cloth_type", so I tried following java code
DBObject fields = new BasicDBObject("id", 1);
fields.put("ClothType","$Info.cloth_type");
DBObject project = new BasicDBObject("$project", fields);
List<DBObject> pipeline = Arrays.asList(project);
AggregationOptions aggregationOptions = AggregationOptions.builder().batchSize(100).outputMode(AggregationOptions.OutputMode.CURSOR).allowDiskUse(true).build();
Cursor cursor = collection.aggregate(pipeline, aggregationOptions);
while (cursor.hasNext())
{
System.out.println(cursor.next());
}
(I don't want to use "$unwind" here)
and get following output:
{ "id" : "p1245" , "ClothType" : [ "C" , "J" , "T"]}
{ "id" : "p124576" , "ClothType" : [ "C"]}
If there are multiple "cloth_type" for single id, then I want only the last cloth_type
from this array.
I want something like, e.g. if there is array of "ClothType
" [ "C", "J", "T"] then I want to project only [ "T"] i.e last element of array.
Is there any ways to achive this without using "$unwind".