Node.js export to csv using - csv-express - node.js

Question

I'm using npm "csv-express" package to export data to CSV. I'm having trouble getting the nested vendor name to display in the exported file. I used the $lookup (aggregation) to get the vendor name from another collection.
Here what the exported file look like:
Here is my query:
db.getCollection('systems').aggregate([
{ "$sort": { "sponsor": 1 } },
{ "$lookup": {
"from": "vendors",
"localField": "vendorID",
"foreignField": "_id",
"as": "vendor"
}
},
{ "$project":{
"sponsor":1,
"address":1,
"city":1,
"state":1,
"vendor.name":1
}
}])
Here's what the query returns:
/* 1 */
{
"_id" : ObjectId("5ab55fee294f2366c054d5eb"),
"sponsor" : "John Doe",
"address" : "123 Western Ave",
"city" : "Los Angeles",
"state" : "CA",
"vendor" : [
{
"name" : "West Interactive"
}
]
}
I tried the following but had no luck.
db.getCollection('systems').aggregate([
{ "$sort": { "sponsor": 1 } },
{ "$lookup": {
"from": "vendors",
"localField": "vendorID",
"foreignField": "_id",
"as": "vendor"
}
},
{ "$project":{
"sponsor":1,
"address":1,
"city":1,
"state":1,
"vendor.[0].name":1
}
}])
Any suggestion would be greatly appreciated!

Answer 1

I found a great article on how to accomplish what I needed.
Here is update query:
db.getCollection('systems').aggregate([
{ "$lookup": {
"from": "vendors",
"localField": "vendorID",
"foreignField": "_id",
"as": "vendor"
}
},
**{ $unwind: "$vendor" },**
{ "$project":{
"sponsor":1,
"address":1,
"city":1,
"state":1,
**"vendorName":"$vendor.name"**
}
}])
This returned the data need for my export.
/* 1 */
{
"_id" : ObjectId("5ab55fee294f2366c054d5eb"),
"sponsor" : "John Doe",
"address" : "123 Western Ave",
"city" : "Los Angeles",
"state" : "CA",
"vendorName" : "Acme Inc."
}