I have want to go from this document:
{
_id: 1,
property: "a",
children: [
{ _id: 2, property: "b" },
{ _id: 3, property: "c" }
]
}
to this:
{ _id: 1, property: "a" }
{ _id: 2, property: "b" }
{ _id: 3, property: "c" }
using a MongoDB aggregate function. I have not found anything suitable. $unwind comes the closest, but doesn't quite lead to the desired result.
You can do it with Aggregation framework:
$concatArrays - to add new property from parent object to the children array$project - to return only children array$unwind - to unwind children array to multiple documents$replaceRoot - to replace to root of the document to the children propertydb.collection.aggregate([
{
"$project": {
"_id": 0,
"children": {
"$concatArrays": [
"$children",
[
{
"_id": "$_id",
"property": "$property"
}
]
]
}
}
},
{
"$unwind": "$children"
},
{
"$replaceRoot": {
"newRoot": "$children"
}
}
])