Limit number of mongodb insertions - node.js

Question

Is there a way to set a fixed limit on the number of documents that can be inserted via a bulk insert in mongodb using the node.js client?
I am inserting a number of documents into a collection that has a unique index on fieldA via a bulk insert. Some of the inserts will fail due to fieldA being non-unique, so I can't know how many will be inserted beforehand, but I want to limit the nInserted so that the total of these documents never goes over 5000.
All I can think to do is to run the full insert and if nInserted brings the total above 5000 I remove the n last inserted documents such that the total is 5000 but this seems a bit silly.
The ordered bulk insert is almost right but I don't want it to stop on the first index conflict but keep going if there is still room (ie < 5000 total).
Here's an example of what I'm trying to achieve:
db.myCol.count({foo: val}, function(err, count) {
var remaining = 5000 - count;
if (remaining > 0) {
var bulk = db.myCol.initializeUnorderedBulkOp();
toInsert.forEach(function(item) {
bulk.insert(item);
});
// make sure no more than remaining is inserted
bulk.execute(function(err, result) {
// currently, I would just insert all and
// then remove the overflow with another db action
// if nInserted + count > 5000
});
}
});

Answer 1

Currently there is no way to tell the Bulk API to stop inserting any records once the limit of successful inserts has been reached.
One way of doing it in the client side,
Feed the Bulk API at most n(5000 in this case) documents at a
time
If any error has occurred during the insert, Bulk insert the
remaining.
Do it recursively.
You can further add logic to process only remaining number of
records if remaining < max.
Modified code:
var toInsert = [..]; // documents to be inserted.
var max = 5000; // max records for Bulk insert.
function execBulk(start,end){
db.myCol.count({foo: 'bar'}, function(err, count) {
var remaining = total - count;
if (remaining > 0 && toInsert.length > start) {
var bulk = db.myCol.initializeUnorderedBulkOp();
toInsert.slice(start,end).forEach(function(item) {
bulk.insert(item);
});
// insert the records
bulk.execute(function(err, result) {
if(err){
console.log(err);
// insert next set of at most 5000 records.
execBulk(end,end+max-1)
}
else
{
console.log(results);
}
});
}
});
}
Invoking the function:
execBulk(0,max);