MongoError: PlanExecutor error during aggregation - mongodb

Question

I have tree records in mongodb but there could be many more, I'm getting shops by an ID coming from frontend
I need to get 20 records and group them by itemId and colorId, and get counts for every shop. the count of shops can be 1,2,3,....10etc..
this is output I need:
+--------+----------+-------+-------+-------+
| itemId | colorId | shop1 | shop2 | shop3 |
+========+==========+=======+=======+=======+
| 1 | colorId1 | 5 | 0 | 3 |
+--------+----------+-------+-------+-------+
| 2 | colorId2 | 3 | 0 | 0 |
+--------+----------+-------+-------+-------+
| 3 | colorId2 | 0 | 3 | 0 |
+--------+----------+-------+-------+-------+
| 2 | colorId1 | 0 | 5 | 0 |
+--------+----------+-------+-------+-------+
| 3 | colorId1 | 0 | 0 | 5 |
+--------+----------+-------+-------+-------+
here is my data and query - here shopId is string and it's work good.
but when I use this query on my local mashine, I'm getting this error:
MongoError: PlanExecutor error during aggregation :: caused by :: $arrayToObject requires an object with keys 'k' and 'v', where the value of 'k' must be of type string. Found type: objectId
but when I change shopId to the ObjectId I'm getting error.
ObjectId versoin

Answer 1

Per your request in the comments (if I got it right):
db.collection.aggregate([
{
"$match": {}// <-- Highly recommend you to use match due to the complexity of this query
},
{
$group: {
_id: 0,
data: {
$push: {
shopId: "$shopId",
shopItems: "$shopItems"
}
},
shopIds: {
"$push": {
shopId: "$shopId",
"count": 0
}
}
}
},
{
$unwind: "$data"
},
{
$unwind: "$data.shopItems"
},
{
$group: {
_id: {
itemId: "$data.shopItems.itemId",
colorId: "$data.shopItems.colorId"
},
data: {
$push: {
shopId: "$data.shopId",
count: "$data.shopItems.itemCount"
}
},
existing: {
$push: {
shopId: "$data.shopId",
"count": 0
}
},
shopIds: {
$first: "$shopIds"
}
}
},
{
"$addFields": {
"missing": {
"$setDifference": [
"$shopIds",
"$existing"
]
}
}
},
{
$project: {
data: {
$concatArrays: [
"$data",
"$missing"
]
}
}
},
{
$unwind: "$data"
},
{
$sort: {
"data.shopId": 1
}
},
{
$group: {
_id: "$_id",
counts: { // here you can change this key
$push: "$data"
},
totalCount: {
$sum: "$data.count" // if you want it
}
}
}
])
After the first $match, we $group in order to get all shopIds in each document.
Next we $unwind and $group by the group you wanted: by colorId and itemId. Then we are adding all the shops with count 0 and removing the ones that do have actual count. Last three steps are just for sorting, summing and formating.
You can play with it here.