I'm quite new in mongodb, now I need to count a $lookup field, is it possible?
I had something like this:
result = await company.aggregate([
{
$lookup: {
from: 'userFocus',
localField: '_id',
foreignField: 'value',
as: 'focusUsers'
}
},
{
$project:{
name: 1,
focusUsers: {userId: 1}
}
}
])
and the result looks like this:
[
{_id: 'xxxx', name: 'first company', focusUsers: [user1, user2, user3...]},
{_id: 'yyyy', name: 'second company', focusUsers: []},
{_id: 'zzzz', name: 'third company', focusUsers: []}
]
Now I want an extra column shows the focusUsers count, in other words, I want a result like the following:
[
{_id: 'xxxx', name: 'first company', focusUsers: [user1, user2, user3], focusCount: 3},
{_id: 'yyyy', name: 'second company', focusUsers: [], focusCount: 0},
{_id: 'zzzz', name: 'third company', focusUsers: [], focusCount: 0}
]
Is it possible? How to do that? Please some experts advice, thanks in advance!
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