mongotemplate aggregation with condition

Question

I have a collection where the documents look like this:

{
  _id: \"545b9fa0dd5318a4285f7ce7\",
  owner: \"admin\",  
  messages: [
    {
      id: \"100\",
          


        

Answer 1

You can use following aggregation :

db.collection.aggregate(
    { $match : { "_id" : ObjectId("545b9fa0dd5318a4285f7ce7") } },
    { $unwind : "$messages" },
    { $group : { "_id" : "$messages.status", "count" : { $sum : 1} } }
)

it will give you the count of status for which message are available, all other status count should be consider 0.