Ето един пример:
> db.baz.find()
> db.baz.insert({
... "_id": ObjectId("4d525ab2924f0000000022ad"),
... "arrayField": [
... { id: 1, other: 23 },
... { id: 2, other: 21 },
... { id: 0, other: 235 },
... { id: 3, other: 765 }
... ],
... "someOtherArrayField": []
... })
WriteResult({ "nInserted" : 1 })
function extractIdZero(arrayFieldName) {
return {$arrayElemAt: [
{$filter: {input: arrayFieldName, cond: {$eq: ["$$this.id", 0]}}},
0
]};
}
extractIdZero("$arrayField")
{
"$arrayElemAt" : [
{
"$filter" : {
"input" : "$arrayField",
"cond" : {
"$eq" : [
"$$this.id",
0
]
}
}
},
0
]
}
db.baz.updateOne(
{_id: ObjectId("4d525ab2924f0000000022ad")},
[{$set: {
arrayField: {$filter: {
input: "$arrayField",
cond: {$ne: ["$$this.id", 0]}
}},
someOtherArrayField: {$concatArrays: [
"$someOtherArrayField",
[extractIdZero("$arrayField")]
]}
}}
])
{ "acknowledged" : true, "matchedCount" : 1, "modifiedCount" : 1 }
> db.baz.findOne()
{
"_id" : ObjectId("4d525ab2924f0000000022ad"),
"arrayField" : [
{
"id" : 1,
"other" : 23
},
{
"id" : 2,
"other" : 21
},
{
"id" : 3,
"other" : 765
}
],
"someOtherArrayField" : [
{
"id" : 0,
"other" : 235
}
]
}