I have a collection in MongoDB:
[
{
"uid": "a1"
},
{
"uid": "a2"
}
]
and a dictionary in my JS code
let dict = { "a1": "ref1", "a1": "ref2" };
I want to do an aggregate that will somehow join the two.
let k = ;
this.model.aggregate([
{
$match: {
uid: { $in: Object.keys(dict) }
}
},
{
$project: {
ref: // here is where I want to add the equivalent reference
}
}
])
The expected output would be something like this:
[{uid: "a1", ref: "ref1"}, {uid: "a2", ref: "ref2}]
Is there a way to get the reference from the dict
into the $project
?
CodePudding user response:
I don't know if there is an easier way to do it, but here's how I achieved it:
db.collection.aggregate([
{
$match: {
uid: {
$in: [
"a1",
"a2"
]
}
}
},
{
"$project": {
"array": {
"$objectToArray": {
"a1": "ref1",
"a2": "ref2"
}
},
"uid": 1,
}
},
{
"$project": {
"ref": {
"$filter": {
"input": "$array",
"as": "elem",
"cond": {
"$eq": [
"$$elem.k",
"$uid"
]
}
}
},
uid: 1,
},
},
{
"$project": {
ref: {
"$arrayElemAt": [
"$ref.v",
0
]
},
uid: 1,
}
}
])
See it working here. I hope you get the idea and convert it into the nodejs equivalent version.