Search location using $near and $geometry in $lookup resulted field - mongodb

Question

The scenario is Employee and they are working in multiple Store Locations, and combine both collections, that is working perfectly,
Problem in: Search in particular location (input lat, long) and this query will give that particular employee working on particular store and that location field is in lookup collection.
Employee
{
"_id": ObjectId("5f03064b3460ef1f10ec2f25"),
"employeeName": "Anonymous",
"stores": [
{
"storeId": ObjectId("5f03030a3460ef1f10ec2f23"),
"workTime": "09:30 to 12:30"
},
{
"storeId": ObjectId("5f03064b3460ef1f10ec2f26"),
"workTime": "01:30 to 02:30"
}
]
}
Store
{
"_id": ObjectId("5f03030a3460ef1f10ec2f23"),
"storeName": "A",
"location": {
"coordinates": ["longitude", "latitude"]
}
}
{
"_id": ObjectId("5f03064b3460ef1f10ec2f26"),
"storeName": "B",
"location": {
"coordinates": ["longitude", "latitude"]
}
}
The below is final result that i am getting successfully:
{
"_id": ObjectId("5f03064b3460ef1f10ec2f25"),
"employeeName": "Anonymous",
"stores": [
{
"storeId": ObjectId("5f03030a3460ef1f10ec2f23"),
"workTime": "09:30 to 12:30",
"storeLocation": {
"storeName": "A",
"location": {
"coordinates": ["longitude", "latitude"]
}
}
},
{
"storeId": ObjectId("5f03064b3460ef1f10ec2f26"),
"workTime": "01:30 to 02:30",
"storeLocation": {
"storeName": "B",
"location": {
"coordinates": ["longitude", "latitude"]
}
}
}
]
}
Aggregation
db.Enmployee.aggregate([
{ "$unwind": "$stores" },
{
"$lookup": {
"from": "Store",
"localField": "stores.storeId",
"foreignField": "_id",
"as": "stores.storeLocation"
}
},
{ "$unwind": "$stores.storeLocation" },
{
"$group": {
"_id": "$_id",
"root": { "$mergeObjects": "$$ROOT" },
"stores": { "$push": "$stores" }
}
},
{
"$replaceRoot": {
"newRoot": {
"$mergeObjects": ["$root", "$$ROOT"]
}
}
},
// <== below $match query will come here
{
"$project": {
"_id": 1,
"employeeName": 1,
"stores.workTime": 1,
"stores.storeLocation.storeName": 1,
"stores.storeLocation.location": 1
}
}
]
)
My goal is to search employee, they are working on particular location of stores using its latitude and longitude, i have tried below query in above aggregation.
{
"$match": {
"stores.storeLocation.location": {
"$near": {
"$maxDistance": 1000,
"$geometry": {
"type": "Point",
"coordinates": ["Input Longitude", "Input Latitude"]
}
}
}
}
}
It gives an error:
Failed to execute script.
Error: command failed: {
"ok" : 0,
"errmsg" : "$geoNear, $near, and $nearSphere are not allowed in this context",
"code" : 2,
"codeName" : "BadValue"
} : aggregate failed
Details:
_getErrorWithCode#src/mongo/shell/utils.js:25:13
doassert#src/mongo/shell/assert.js:18:14
_assertCommandWorked#src/mongo/shell/assert.js:534:17
assert.commandWorked#src/mongo/shell/assert.js:618:16
DB.prototype._runAggregate#src/mongo/shell/db.js:260:9
DBCollection.prototype.aggregate#src/mongo/shell/collection.js:1062:12
DBCollection.prototype.aggregate#:1:355
#(shell):1:1

Answer 1

$geoNear is a pipeline stage itself and you can not use it inside $match. Also, it should be the first stage of the pipeline, so you need to declare it in the $lookup pipeline.
Note that you also need to have a geo index for that use:
db.getCollection('Store').createIndex( { "location.coordinates" : "2dsphere" } )
After the changes mentioned above, the query will look like as below:
db.Employee.aggregate([
{ "$unwind": "$stores" },
{
"$lookup": {
from: "Store",
let: {
storeId: "$stores.storeId"
},
pipeline: [
{ $geoNear: {
includeLocs: "location",
distanceField: "distance",
near: {type: 'Point', coordinates: [57, 35]},
maxDistance: 1000,
spherical: true}},
{
$match: {
$expr: { $eq: ["$$storeId", "$_id"] }
}
}
],
as: "stores.storeLocation"
}
},
{ "$unwind": "$stores.storeLocation" },
{
"$group": {
"_id": "$_id",
"root": { "$mergeObjects": "$$ROOT" },
"stores": { "$push": "$stores" }
}
},
{
"$replaceRoot": {
"newRoot": {
"$mergeObjects": ["$root", "$$ROOT"]
}
}
},
// <== below $match query will come here
{
"$project": {
"_id": 1,
"employeeName": 1,
"stores.workTime": 1,
"stores.storeLocation.storeName": 1,
"stores.storeLocation.location": 1
}
}
]
)
You can findout more about $geoNear options here.