I'm trying to make a function inside an async.waterfall that checks each id in an array if there is any entry in a mongodb with this id (using Mongoose). If the id already exists it's to be removed from the array. I wrote the following function:
function(eventIds, callback) {
// check for duplicates
for (var i = 0; i < eventIds.length; i++) {
var query = Party.find({
fbEventId: eventIds[i]
});
query.exec(function(err, doc) {
if (err) return console.log(err);
if (doc) {
// remove i from array
console.log(doc);
}
});
}
callback(null, eventIds);
}
This however gives a warning because a new function is constructed in a for loop.
If i create the function outside the for loop like below it gives an error: ReferenceError: err is not defined.
function(eventIds, callback) {
// check for duplicates
function checkDuplicate(err, doc) {
if (err) return console.log(err);
if (doc) {
// remove i from array
console.log(doc);
}
}
for (var i = 0; i < eventIds.length; i++) {
var query = Party.find({
fbEventId: eventIds[i]
});
query.exec(checkDuplicate(err, doc));
}
callback(null, eventIds);
}
What would be the proper way to do this?
You are calling the function, not assigning a reference to it.
Your code
query.exec(query.exec(checkDuplicate(err, doc));
should be
query.exec(query.exec(checkDuplicate));
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