How to fetch single matched document from nested array mongodb? - node.js

Question

I have nested array object in my MongoDB document, but the predicate is not return as expected, which in this case I only want matched document only.
Document Structure
{
"_id": {
"$oid": "5fddb34848be35283c36955b"
},
"projectId": {
"$oid": "5fddb30d48be35283c36955a"
},
"urls": [
{
"_id": {
"$oid": "5fddb34848be35283c36955c"
},
"group": "User",
"data": [
{
"option": {
"applyDifferentContentType": false,
"allowInjection": false
},
"_id": {
"$oid": "5fddad1e48be35283c369558"
},
"url": "/users/create",
"method": "patch",
"headers": {
"Content-Type": "multipart/form-data"
}
},
{
"option": {
"applyDifferentContentType": false,
"allowInjection": false
},
"_id": {
"$oid": "5fddad1e48be35283c369558"
},
"url": "/users/update",
"method": "post",
"headers": {
"Content-Type": "application/json"
}
},
{
"option": {
"applyDifferentContentType": false,
"allowInjection": false
},
"_id": {
"$oid": "5fddad1e48be35283c369558"
},
"url": "/users/delete",
"method": "post",
"headers": {
"Content-Type": "application/json"
}
}
]
},
{
"_id": {
"$oid": "5fddb34f48be35283c36955d"
},
"group": "Project",
"data": [
{
"option": {
"applyDifferentContentType": true,
"allowInjection": false
},
"_id": {
"$oid": "5fddad1e48be35283c369558"
},
"url": "/project/create",
"method": "post",
"headers": {
"Content-Type": "application/json"
}
},
{
"option": {
"applyDifferentContentType": false,
"allowInjection": false
},
"_id": {
"$oid": "5fddad1e48be35283c369558"
},
"url": "/projects/update",
"method": "post",
"headers": {
"Content-Type": "application/url-encoded"
}
}
]
},
{
"_id": {
"$oid": "5fddb37d48be35283c36955e"
},
"group": "Contact",
"data": [
{
"option": {
"applyDifferentContentType": false,
"allowInjection": false
},
"_id": {
"$oid": "5fddad1e48be35283c369558"
},
"url": "/contact/create",
"method": "post",
"headers": {
"Content-Type": "multipart/form-data"
}
}
]
}
],
"__v": 0 }
Fetch Query
const result = await URLPayload.find({
"projectId": projectId,
"urls.data": {
$elemMatch: {
"_id": dataId
}
}
})
.lean();
projectId => 5fddb30d48be35283c36955a
dataId => 5fddad1e48be35283c369558
But above predicate is not giving expected result.
How to return only matched single document from nested array object ?
I have nested array object in my MongoDB document, but the predicate is not return as expected, which in this case I only want matched document only.

Answer 1

You can use aggregation pipeline,
make your you have to convert projectId and dataId input fields string type to object type using mongoose.Types.ObjectId
$match your conditions,
$project to show required documents
$reduce to iterate loop of urls array
$filter to iterate loop of urls.data array and filter matching _id,
$first will return object from the array, you can use $arrayElemAt instead of $first for older version of MongoDB
const result = await URLPayload.aggregate([
{
$match: {
projectId: mongoose.Types.ObjectId(projectId),
"urls.data._id": mongoose.Types.ObjectId(dataId)
}
},
{
$project: {
urlData: {
$reduce: {
input: "$urls",
initialValue: {},
in: {
$first: {
$filter: {
input: "$$this.data",
cond: { $eq: ["$$this._id", mongoose.Types.ObjectId(dataId)] }
}
}
}
}
}
}
}
])
Playground

Answer 2

I'm not used working with $oid inside the _id element but this should work.
const ids = {
projectId: "5fddb30d48be35283c36955a",
urlId: "5fddb34848be35283c36955c",
dataId: "5fddad1e48be35283c369558"
}
await URLPayload.findOne({ "projectId.$oid": ids.projectId },
{
"$elemMatch": { "urls.$[url].data": { "_id.$oid": ids.dataId } }
}, {
"arrayFilters": [
{ "url._id.$oid": ids.urlId }
]
}, (err, urlPayloadResult) => {
if (err) {
console.log(err)
} else {
console.log({ message: urlPayloadResult })
}
})
If not work in your case just remove the ".$oid" element.
Let me know if this work.