I have the following dataset, where I have two types of objects discriminate by the field lType
that can be either base
or extra
. extra has a ref to a base
location.
[
{
"_id": "622b6f1c7a0aca9aa252756c",
"country": "US",
"county": "Florida",
"city": "Miami",
"lType": "base",
"displayString": "Florida,Miami",
"__v": 0
},
{
"_id": "622b6f1d7a0aca9aa252756e",
"landmark": "Gas station",
"baseLocation": "622b6f1c7a0aca9aa252756c",
"lType": "extra",
"displayString": "Florida,Miami,Gas station",
"__v": 0
},
{
"_id": "622b6f4c5d0fe602a18826a7",
"country": "US",
"county": "Florida",
"city": "Tampa",
"lType": "base",
"displayString": "Florida,Tampa",
"__v": 0
},
{
"_id": "622b6f4c5d0fe602a18826a9",
"landmark": "Downtown",
"baseLocation": "622b6f4c5d0fe602a18826a7",
"lType": "extra",
"displayString": "Florida,Tampa,Downtown",
"__v": 0
}
]
When I try to do an aggregation lookup like this
const location = await Location.collection.aggregate([{
$lookup: {
from: 'location',
localField: 'baseLocation',
foreignField: '_id',
as: 'locationData'
}
}]).toArray();
I get an empty array in locationData
for my extra
locations even though my baseLocation
field is an ObjectId pointing to a base
location object.
CodePudding user response:
I think you have a typo. Instead of from: 'location'
, it should be from: 'locations'
.
Try to change your code like this:
const location = await Location.collection.aggregate([{
$lookup: {
from: 'locations',
localField: 'baseLocation',
foreignField: '_id',
as: 'locationData'
}
}]);