Conditional upsert based on custom id of nested documents in Meteor

Question

This doesn't work, but hopefully this and the mouthful of a title gets the point across

function addToDB(account_id)
{
    obj = {};
    if (!Accounts.findOne({account_id: account_id})) obj.createdAt = new Date().valueOf();
    obj.account_id = account_id;
    Accounts.upsert({account_id: account_id}, {$set: obj});
}

I need to use the account_id instead of the MongoDB object id, so it has to be indexable/unique. If it's an update, the createdAt shouldn't change.

UPDATED so it works in the original context, but I prefer the solution I comment with to the correct answer.

Answer 1

I doubt this is supported in the minimongo side of things, but you can always implement the logic on the server and publish the method. But MongoDB supplies a $setOnInsert operator which has the purpose of only applying that value to the update performed when the "upsert" in fact inserts a new document:

Accounts.upsert(
    { "account_id": obj.account_id }, 
    { 
        "$setOnInsert": { "created_at": new Date() },
        "$set": obj // account_id would be automatically added but it doesn't matter
    }

);

Of course presuming that obj does not already contain aa created_at field and the data you want is actually a BSON "Date" type rather than an epoch timestamp ( BSON Dates actually store as an epoch timestamp internally anyway ) otherwise convert using .valueOf() as shown in your example.