Mongoose - push if array else update - node.js

Question

My schema looks like this:
{
_id: mongoose.Schema.Types.ObjectId,
timestamp: { type: Date, default: Date.now },
uid: { type: String, required: false, immutable: true },
gid: [
{
type: String
}
],
status: { type: String, required: false }
}
I want to be able to save a new object everytime uid is new and update it when it already exists. So basically saving this object:
{
uid: "xyz",
gid: "123"
}
should produce
{
_id: ObjectId("123"),
uid: "xyz",
gid: ["123"]
// note that if status is not provided it shouldn't appear here as `null`
}
Then again if this object is saved:
{
uid: "xyz",
gid: "345",
status: "new"
}
it should produce:
{
_id: ObjectId("123"),
uid: "xyz",
gid: ["123","345"]
status: "new"
}
and lastly for this object:
{
uid: "xyz",
gid: "345",
status: "old"
}
the expected result would be
{
_id: ObjectId("123"),
uid: "xyz",
gid: ["123","345"]
status: "old"
}
Is this possible to achieve in a single query? Sorry if my explenation is complicated, I don't know how else to put it.

Answer 1

Case1: only status changes and array exists, the below code, won't add a new element
> //actual code output from Mongo shell 4.2 on windows10 OS
> //use add to set and set update to acheive your update goals(array vs addition
> //of fields in two updates
> //add to set checks for an array element is present in array, if it is present it does nothing
> //else it will add the element in the array
> //pre-update document check
> db.ugs.find().pretty();
{
"_id" : ObjectId("5f625d864651219e25c775c1"),
"uid" : "xyz",
"gid" : [
"345",
"123",
"100",
"200"
],
"status" : "old"
}
> var v_status = "new";
> db.ugs.aggregate([
... {$match:{uid: "xyz"}}
... ]).forEach(function(doc){
... print("uid: ", doc.uid);
... print("gid: ",doc.gid);
... print("pre-status: ", doc.status);
... db.ugs.update(
... {"_id":doc._id},
... {$addToSet:{gid:"200"}
... });
... db.ugs.update(
... {"_id":doc._id},
... {$set:{status:v_status}}
... );
... print("post-status: ", v_status);
... });
uid: xyz
gid: 345,123,100,200
pre-status: old
post-status: new
> //post update document check
> db.ugs.find().pretty();
{
"_id" : ObjectId("5f625d864651219e25c775c1"),
"uid" : "xyz",
"gid" : [
"345",
"123",
"100",
"200"
],
"status" : "new"
}
>
Case2: change status as well add element if it does not exists in array
> //pre-update document check
> db.ugs.find().pretty();
{
"_id" : ObjectId("5f625d864651219e25c775c1"),
"uid" : "xyz",
"gid" : [
"345",
"123",
"100",
"200"
],
"status" : "new"
}
> var v_status = "old";
> db.ugs.aggregate([
... {$match:{uid: "xyz"}}
... ]).forEach(function(doc){
... print("uid: ", doc.uid);
... print("gid: ",doc.gid);
... print("pre-status: ", doc.status);
... db.ugs.update(
... {"_id":doc._id},
... {$addToSet:{gid:"444"}
... });
... db.ugs.update(
... {"_id":doc._id},
... {$set:{status:v_status}}
... );
... print("post-status: ", v_status);
... });
uid: xyz
gid: 345,123,100,200
pre-status: new
post-status: old
> //post update document check
> db.ugs.find().pretty();
{
"_id" : ObjectId("5f625d864651219e25c775c1"),
"uid" : "xyz",
"gid" : [
"345",
"123",
"100",
"200",
"444"
],
"status" : "old"
}
>
Case3: set and unset the value of the status field as needed.
> db.ugs.find().pretty();
{
"_id" : ObjectId("5f625d864651219e25c775c1"),
"uid" : "xyz",
"gid" : [
"345",
"123",
"100",
"200",
"444"
],
"status" : ""
}
> var v_status = "";
> db.ugs.aggregate([
... {$match:{uid: "xyz"}}
... ]).forEach(function(doc){
... print("uid: ", doc.uid);
... print("gid: ",doc.gid);
... print("pre-status: ", doc.status);
... db.ugs.update(
... {"_id":doc._id},
... {$addToSet:{gid:"444"}
... });
... db.ugs.update(
... {"_id":doc._id,status:{$exists:true}},
... {$set:{status:v_status}}
... );
... print("post-status: ", v_status);
... });
uid: xyz
gid: 345,123,100,200,444
pre-status:
post-status:
> //post update document check
> db.ugs.find().pretty();
{
"_id" : ObjectId("5f625d864651219e25c775c1"),
"uid" : "xyz",
"gid" : [
"345",
"123",
"100",
"200",
"444"
],
"status" : ""
}
//unset the field if not required, it will not show in the document
> var v_status = "";
> db.ugs.aggregate([
... {$match:{uid: "xyz"}}
... ]).forEach(function(doc){
... print("uid: ", doc.uid);
... print("gid: ",doc.gid);
... print("pre-status: ", doc.status);
... db.ugs.update(
... {"_id":doc._id},
... {$addToSet:{gid:"444"}
... });
... db.ugs.update(
... {"_id":doc._id,status:{$exists:true}},
... {$unset:{status:v_status}}
... );
... print("post-status: ", v_status);
... });
uid: xyz
gid: 345,123,100,200,444
pre-status: [unknown type]
post-status:
> //post update document check
> db.ugs.find().pretty();
{
"_id" : ObjectId("5f625d864651219e25c775c1"),
"uid" : "xyz",
"gid" : [
"345",
"123",
"100",
"200",
"444"
]
}
>

Answer 2

You're looking the upsert option to add a new doc if it doesn't exist already. Combined with the addToSet atomic opperator to create the array of gids.
You'll have to break the object into $set and $addToSet updaters with rest.
let saveObj = {
uid: "xyz",
gid: "123"
};
let {gid, ...setFields} = saveObj;
YourModel.updateOne(
{uid: setFields.uid},
{$set: setFields, $addToSet: {gid}},
{upsert: true}
).then(...);