I am using meteorhacks:aggregate package to do Mongo aggregation in Meteor. I want to get the count at the last stage of the pipeline so I use this code:
Message.aggregate([
{
$match: {
// ...
}
}, {
$count: 'count'
}
]);
It is pretty simple and should work, but I only get this error:
Exception while invoking method 'methodname'
MongoError: Unrecognized pipeline stage name: '$count'
...
Please help, thanks.
Updated: this question is not duplicated as an editor suggested, my main intention is to find out why I can not use $count
$count is available in mongodb version 3.4. For previous versions,
you will need to use $group over a constant field.
Message.aggregate([
{
$match: {
// ...
}
}, {
$group: {
_id : null,
count : {$sum : 1}
}
}
]);