MongoDB: How to group nested arrays in one document?

Question

I have the following Collection:

{
    id: 23423-dsfsdf-32423,
    name: Proj1,
    services: [
         {
            id:sdfs-24423-sdf,
            name:P1_Ser         


        

Answer 1

You need to group on null _id so that all services get grouped in single document. Also $unwind the services array before grouping, else group will give you array of arrays

db.project.aggregate(
  {$unwind: '$services'},
  {$group: {_id:null, services: {$push: '$services'}}}
)