I want to know how to use aggregate() to take all of the objects of a specific field (i.e. "user") and count them.
This what I am doing:
I want to return a list of users with the sum of how many tweets that have made?
So I want output that looks like
Etc..
Also I don't want repeating users like
Etc..
which is what the above aggregate does.
So basically, how can I modify this aggregate to ensure the objects are unique?
I believe you will want to group by the user.id field instead of the user object. You can try doing that directly
$group: {_id: "$user.id", totalTweets: {$sum: 1} }
Or you might want to try projecting that field onto the document before grouping
$addFields: {userId: "$user.id"}
$group: {_id: "$userId", totalTweets: {$sum: 1} }
If you want whole inner user object in each documents after aggregation then you have to use $push operator in aggregation
and also you need to do the aggregation on unique id of users e.g: id or id_str instead of $user object as in your question.
db.tweets.aggregate([{ $group: {_id: "$user.id", totalTweets: { $sum: 1 }, user : { $push: "$user" } } }])
This will solved your problem. For details about $push operator, have a look at official documents $push
