How to count and sum the same value of size where stock is equal to 'Available' in one of mongodb collection.
desired result as below:
{_id :'S',count: 5 }, {_id :'M',count: 2 }, {_id :'L',count: 1 }
"price" : 123.8,
"gender" : "women",
"colour" : "blue",
"item" : [
{
"name" : "ICE DUO ANTHRACITE YELLOW SMALL (S)",
"size" : "S",
"stock" : "Available",
"_id" : ObjectId("59b2829e5acd8e2d14aa84cf")
},
{
"name" : "ICE DUO ANTHRACITE YELLOW SMALL (L)",
"size" : "L",
"stock" : "Available",
"_id" : ObjectId("59b2829e5acd8e2d14aa84ce")
},
{
"name" : "ICE DUO ANTHRACITE YELLOW SMALL (M)",
"size" : "M",
"stock" : "Available",
"_id" : ObjectId("59b2829e5acd8e2d14aa84cd")
}
],