Aggregation issue with 2 collections - node.js

Question

The purpose of this is to fetch A pro of Type Secretaire from a Cabinet with a specified name (in this case "Clinique Toto") and I'm struggling here.
Cab Model:
var cabinet = new cabModel({
_id: new mongoose.Types.ObjectId(),
InfoCab:{Nom: "Clinique Toto"} //This is the Name of the Cabinet
});
cabinet.save((err, cabinet) => {
Pro Model
var pro1 = new proModel({
_id: new mongoose.Types.ObjectId(),
Nom: 'ProTITI',
Cv:{ Fonction: { Secretaire: false}}
});
pro1.Cabinets.push(cabinet._id);
pro1.save((err, cabinet) => { });
var pro2 = new proModel({
_id: new mongoose.Types.ObjectId(),
Nom: 'Pro_TOT',
Cv:{ Fonction: { Secretaire: true}}
});
Setting Secretaire: true for some of the Pros.
pro2.Cabinets.push(cabinet._id);
pro2.save((err, cabinet) => { });
var pro3 = new proModel({
_id: new mongoose.Types.ObjectId(),
Nom: 'Josianne',
Cv:{ Fonction: { Secretaire: true}}
});
pro3.Cabinets.push(cabinet._id);
pro3.save((err, cabinet) => { });
Pushing Pros created into the Cab.
cabinet.Pro.push(pro1, pro2, pro3);
cabinet.save();
console.log("Done");
});
const handleError = function (err) {
console.error(err);
};
I got to this so far:
db.Pro.aggregate([
{
$match: {
Cv: {
Fonction: {
Secretaire: true
}
}
}
},
{
$lookup:
{
from: "Cab",
localField:"Nom",
foreignField: "_id",
as: "PK"
}
}
])
Here are the Schemas:
Pro Schema:
const ProSchema = new Schema({
_id: { type: Schema.Types.ObjectId },
Cv: {Fonction: {Pro: {type: Boolean,},
Secretaire: {type: Boolean}
}
}
CabSchema:
const CabSchema = new Schema({
Pro: [{ type: Schema.Types.ObjectId, ref: 'ProSchema' }],
InfoCab: {
Nom: {type: String}
});

Answer 1

Can you add Schema for your models so your question has more clarification.
From the given information, it looks like Nom is a string, i.e. Nom: 'Josianne' and you are using lookup as follows:
$lookup:
{
from: "Cab",
localField:"Nom",
foreignField: "_id",
as: "PK"
}
Now the problem is _id is of type ObjectId(), which is a hash string uniquely generated, where Nom is a string created by you, logically they will never match.
iF Cab collection is same as cabModel, the foreignField should be InfoCab.Nom. i.e. foreignField: "InfoCab.Nom",
=== UPDATE ===
Couple of observations you might wana consider:
you should use the aggregation as following: proModel.aggregate([...])
If you are already using ref in your mongoose schema, you can use .populate() method.