W takiej sytuacji$facet
pomoc w kategoryzacji przychodzących danych
db.Collection_A.aggregate([
{ $unwind: "$includes },
{
"$facet": {
"joinB": [
{
"$lookup": {
"from": "Collection_B", "localField": "includes.includes_id",
"foreignField": "_id", "as": "includes.includes_list"
}
},
{
"$group": {
"_id": "$_id",
"name": { "$first": "$name" },
includes: { $push: "$includes" }
}
}
],
"joinC": [
{
"$lookup": {
"from": "Collection_C", "localField": "includes.includes_id",
"foreignField": "_id", "as": "includes.includes_list"
}
},
{
"$group": {
"_id": "$_id",
"name": { "$first": "$name" },
includes: { $push: "$includes" }
}
}
],
"joinD": [
{
"$lookup": {
"from": "Collection_D", "localField": "includes.includes_id",
"foreignField": "_id", "as": "includes.includes_list"
}
},
{
"$group": {
"_id": "$_id",
"name": { "$first": "$name" },
includes: { $push: "$includes" }
}
}
],
}
},
{
$project: {
combined: {
"$concatArrays": [ "$joinB", "$joinC", "$joinD" ]
}
}
},
{ "$unwind": "$combined" },
{
"$replaceRoot": { "newRoot": "$combined" }
},
{
"$project": {
_id: 1,
name: 1,
includes: {
$filter: {
input: "$includes",
cond: {
$ne: [ "$$this.includes_list",[] ]
}
}
}
}
}
])
Praca Plac zabaw Mongo
Uwaga:czuję, że jest to rodzaj anty-wzoru, za którym podążasz. Jeśli jesteś na wczesnym etapie projektu, lepiej zmień strukturę, jeśli się nie mylę.