Mongoose remove subdocument - node.js

Question

I am struggling to get subdocument removed from the parent.
I am using Mongoose findOneAndUpdate.
unitRouter.delete('/:id/contracts/:cid', async (req, res) => {
Unit.findOneAndUpdate(
{ id: req.params.id },
{$pull: {contracts: { id: req.params.cid }}},
function(err, data){
console.log(err, data);
});
res.redirect(`/units/${req.params.id}`);
});
Schema is as follows:
const unitSchema = new mongoose.Schema({
address: {
type: String,
required: true
}
contracts: [{type: mongoose.Schema.Types.ObjectId, ref: 'Contract'}]
});
And it doesn't remove it from the list, neither from the contract collection.
I have checked similar topics, but didn't got it to work. What am I missing?

Answer 1

First of all, your schema does not match with your query.
Your schema doesn't have any id. Do you mean _id created by default?
contracts field is an array of ObjectId, not an object like { id: XXX }
So, starting from the schema you can have a collection similar to this:
[
{
"contracts": [
"5a934e000102030405000000",
"5a934e000102030405000001",
"5a934e000102030405000002"
],
"_id": "613bd938774f3b0fa8f9c1ce",
"address": "1"
},
{
"contracts": [
"5a934e000102030405000000",
"5a934e000102030405000001",
"5a934e000102030405000002"
],
"_id": "613bd938774f3b0fa8f9c1cf",
"address": "2"
}
]
With this collection (which match with your schema) you need the following query:
Unit.updateOne({
"_id": req.params.id
},
{
"$pull": {
"contracts": req.params.cid
}
})
Example here.
Also, the inverse way, your query is ok but your schema doesn't. Then you need a schema similar to this:
new mongoose.Schema(
{
id:{
type: mongoose.Schema.Types.ObjectId,
required: true
},
address: {
type: String,
required: true
},
contracts: [{
id:{
type: mongoose.Schema.Types.ObjectId,
ref: 'Contract'
}
}]
});
Example here
By the way, take care to not confuse between id and _id. By default is created the field _id.