Complex aggregation queries Mongodb - Examples

 Group and slice array

@Aggregation(pipeline = {
        "{ $match: {'category':{$regex : ?0, $options: 'i'}}}",
        "{ $group: { _id: {category:'$category'}, data: { $push: '$$ROOT' } } }",
        "{ $project: { _id: 0, category:'$_id.category', videos:{ $slice:['$data',?1,?2]} }"

})