mongodb- How to display a year from a date in find method - mongodb

Question

Im trying to display the years of date properties in a mongodb collection.
I have collection of vehicles that contains objects with a date property:
manufacturingDate - Date (ISODate).
To display only the years there is one way to this with aggregate:
db.vehicles.aggregate(
[
{ $project: { year: { $year: "$manufacturingDate" } } }
]
)
But I am not allowed to use aggregate so i need a way to take the year out of the ISODate in another way.
I have tried many things like:
db.vehicles.find({}, { manufacturingDate: { $year: 1 } } )
or:
db.vehicles.find({}, { year: { function() { return this.manufacturingDate.getFullYear() } } } )
But these are all syntax errors.
So i hope you have a correct way to do this without aggregate. I prefer the find method but any other method will be good.
Thanks.

Answer 1

Here are two ways to do it. Of course; it would be nicer if we could just execute getFullYear within a forEach applied to the find() but this is what works for me so far.
I found this on [link]http://grokbase.com/t/gg/mongodb-user/133nvkd48q/how-to-format-output-datetime and tweaked the example. Obviously there is more here than you need bu I left the extra bits for clarity.
//first create a function to handle the execution of the getFullYear function on the ISODate field.
function parse_date(obj) {
year = obj['manufacturingDate'].getFullYear();
month = obj['manufacturingDate'].getMonth() + 1;
day = obj['manufacturingDate'].getUTCDate();
hour = obj['manufacturingDate'].getUTCHours();
minute = obj['manufacturingDate'].getUTCMinutes();
obj['manufacturingDate'] = year + '/' + month + '/' + day + ' ' + hour +
':' + minute
//printjson(obj);
printjson(year);
}
//then execute your query and apply the parse_date function above within
the forEach of the find method.
db.sample.find({},{manufacturingDate:1}).forEach(parse_date)
You can also iterate over the resultset as a cursor and applying the getFullYear function against the ISODate field.
//iterate over cursor
var mdate = myDocument.manufacturingDate;
print (mdate.getFullYear());