How to get an object's array's specific objects with mongo query?-CodePudding

I have tried the following queries and they all return an object that contains an array of all the objects in the array.

dbCollection.find({ user: req.user._id, "books.type": type });
dbCollection.find({ user: req.user._id, books: { $elemMatch: { type } } });
dbCollection.find({ $and: [{ user: req.user._id }, { "books.type": type }] });
dbCollection.find({ user: req.user._id, "books.type": { $in: type } });
dbCollection.find({ user: req.user._id, "books.type": { $in: [type] });

How to get only those objects of array which match the condition instead of whole array?

CodePudding user response：

This will work I think, give it a try

dbCollection.aggregate([
            { $match: { user: { $eq: req.user._id } } },
            {
                $project: {
                    user: 1,
                    books: {
                        $filter: {
                            input: "$books",
                            as: "book",
                            cond: { $eq: ["$$book.type", type] },
                        },
                    },
                },
            },
        ]);