How to perform $lookup aggregation query deep into field in mongodb?

Question

How to perform properly $lookup aggregation query deep into field in mongodb?

templates

{
    "_id": ObjectID("589888769ffec515d86f3e6c"),
    "tpl_name": "t1",
    "tpl_user": "some"
},
{
    "_id": ObjectID("589888769ffec123386f3222"),
    "tpl_name": "t2",
    "tpl_user": "some"
}

subscriptions

{
  "_id": ObjectID("58c182ed320386f56a518efb"),
    "data": {
        "template": "589888769ffec515d86f3e6c",
        "email": "some.email@gmail.com"
    }
},
{
    "_id": ObjectID("58c182ed320386f56a518e7f"),
    "data": {
        "template": "589888769ffec515d86f3e6c",
        "email": "some.email@gmail.com"
    }
}

Need to get list of templates with subscriptions in it.

I tried to get it like that.

db.collection('templates').aggregate([
    {$match: { 'tpl_user': tpl_user.id }},
    {
        $lookup: {
            from: "subscriptions",
            localField: "_id",
            // tried to use foreignField like that
            foreignField: "data.template",
            as: "subscriptions"
        }
    },
])

But no dice. Query returns empty subscriptions array.