Моля, използвайте ключова дума addFields, след като можем да използваме ключ в проекта .
const LEAD_PRICE = ....; // doesn't matter
Client.aggregate(
[
{
$lookup: {
from: "clientboughtleads",
localField: "_id",
foreignField: "Client",
as: "ClientLeads"
}
},
{
$addFields: {
TotalPurchasedLeads: {
$size: "$ClientLeads"
}
}
},
{
$project: {
ClientId: "$_id",
RegistrationDate: "$date",
TotalPurchasedLeads:1,
IncomeFromClient: { // This one is always undefined
$multiply: [LEAD_PRICE / 2, "$TotalPurchasedLeads"]
}
}
}
]