MongoDB Aggregation - Creating new arrays from a given array - mongodb

Question

i wish to create new arrays from a given array based on my aggregation results, the desired outcome from the following doc is to split the array into new arrays where the split point is the action "start"
{
"_id" : "5f851b06b08ab4b1f916c14841d4bbba",
"actions" : [
{
"action" : "start",
"datetime" : 1525692527345.0
},
{
"action" : "scrolled",
"datetime" : 1525692545966.0
},
{
"action" : "scrolled",
"datetime" : 1525692545983.0
},
{
"action" : "click",
"datetime" : 1525692545999.0
},
{
"action" : "start",
"datetime" : 1525693343877.0
},
{
"action" : "mousemove",
"datetime" : 1525693351075.0
},
{
"action" : "mousemove",
"datetime" : 1525693351117.0
},
{
"action" : "scrolled",
"datetime" : 1525693351212.0
},
{
"action": "scrolled",
"datetime": 1525693354026.0
},
{
"action": "scrolled",
"datetime": 1525693354126.0
}
]
}
so next i should have a document that looks like this:
{
"_id": "5f851b06b08ab4b1f916c14841d4bbba",
"session1": [
{
"action": "start",
"datetime": 1525692527345.0
},
{
"action": "scrolled",
"datetime": 1525692545966.0
},
{
"action": "scrolled",
"datetime": 1525692545983.0
},
{
"action": "click",
"datetime": 1525692545999.0
}
],
"session2": [
{
"action": "start",
"datetime": 1525693343877.0
},
{
"action": "mousemove",
"datetime": 1525693351075.0
},
{
"action": "mousemove",
"datetime": 1525693351118.0
},
{
"action": "mousemove",
"datetime": 1525693351119.0
},
{
"action": "mousemove",
"datetime": 1525693351121.0
},
{
"action": "scrolled",
"datetime": 1525693351212.0
},
{
"action": "scrolled",
"datetime": 1525693354026.0
},
{
"action": "scrolled",
"datetime": 1525693354126.0
}
]
}
the session1, session2 field name can be anything it's just for the sake of showing the desired result.
any ideas how to add this to my existing aggregation pipeline?
db.collection.aggregate(
[
{
"$match" : {
"action" : {
"$exists" : true
},
"domain" : "domain.com"
}
},
{
"$unwind" : "$action"
},
{
"$sort" : {
"action.datetime" : 1.0
}
},
{
"$group" : {
"_id" : "$id",
"count" : {
"$sum" : 1.0
},
"actions" : {
"$addToSet" : {
"id" : "$id",
"action" : "$action.action",
"datetime" : "$action.datetime"
}
}
}
},
{
"$unwind" : "$actions"
},
{
"$sort" : {
"actions.datetime" : 1.0
}
},
{
"$group" : {
"_id" : "$actions.id",
"count" : {
"$sum" : 1.0
},
"actions" : {
"$push" : {
"action" : "$actions.action",
"datetime" : "$actions.datetime"
}
}
}
},
{
"$match" : {
"count" : {
"$gt" : 1.0
}
}
}
],
{
"allowDiskUse" : true
}
);
Thanks for looking!