Project after nested lookup

Working with Data
1

Hey all,

A noob here trying to understand a somewhat complex aggregate thing. I can I $project certain fields in a after a nested $lookup. See the { $project: { “uid.email”: 1 } },

this.aggregate([
        {
          $facet: {
            meta: [{ $match: query }, { $count: "totalHits" }],
            items: [
              { $match: query },

              {
                $addFields: {
                  id: { $toString: "$_id" },
                },
              },

              { $sort: sorting },
              { $skip: perPage * (page - 1) },
              { $limit: perPage },
              {
                $lookup: {
                  from: 'users',
                  localField: 'uid',
                  foreignField: '_id',
                  as: 'uid',
                },
              },
              { "$unwind": "$uid" },
              {
                $lookup: {
                  from: 'items',
                  localField: 'items.item',
                  foreignField: '_id',
                  as: 'items',
                },
              },
             // Here is where I would like to $project only certain fields in the array from the $lookup above
            ],
            matchingTags: [
              { $match: query },
              { $project: { tags: 1 } },
              { $unwind: "$tags" },
              { $group: { _id: "$tags", count: { $sum: 1 } } },
              { $sort: { count: -1 } },
            ],
          },
        },
      ])

Any hints?