Why won't my insert callback run? - mongodb

Question

I'm running the following from the mongodb console (it's in a js file called via load()), but the callback to the insert never runs even though all the database insertions happen as expected. Can anyone see why?
db.oldsets.find().forEach(function (set) {
var newSet = {
tunes: [],
keys: []
};
set.tunes.forEach(function (arr) {
if (newSet) {
var tune = db.oldtunes.findOne({
_id: arr.tune
})
var newTune = db.getSiblingDB('jnr_local').tunes.findOne({
sessionId: tune.sessionId
})
if (newTune) {
newSet.tunes.push(newTune._id);
newSet.keys.push(arr.root + tune.mode);
} else {
newSet = null;
}
}
})
print('out') // outputs for every iteration
if (newSet) {
db.sets.insert(newSet, function (err, doc) {
print('in') // never outputs
db.practices.insert({
type: 'set',
// srcId: doc[0]._id,
stickyness: 0
});
});
} else {
print('else') // never outputs
db.dodgySets.insert(set);
}
});

Answer 1

It looks like you are mixing node.js and mongodb shell. In mongodb shell all code is synchronous and run line by line.
So the db.sets.insert will simply return inserted document.
So, try to rewrite it as follow:
if (newSet) {
insertedSet = db.sets.insert(newSet);
print('in') // never outputs
db.practices.insert({
type: 'set',
srcId: insertedSet._id,
stickyness: 0
});
}
Hope this helps!