Database

[{"products":[{"name":"soccer ball","price":25},{"name":"spiral notebook","price":5},{"name":"gel pen","price":3},{"name":"water bottle","price":15},{"name":"backpack","price":30}]},{"products":[{"name":"basketball","price":20},{"name":"composition notebook","price":8},{"name":"fountain pen","price":12},{"name":"duffle bag","price":50},{"name":"sports shoes","price":60}]},{"products":[{"name":"tennis ball","price":10},{"name":"journal","price":7},{"name":"mechanical pencil","price":2},{"name":"hand towel","price":6},{"name":"headband","price":9}]},{"products":[{"name":"volleyball","price":18},{"name":"sketchbook","price":14},{"name":"marker","price":3},{"name":"knee pads","price":25},{"name":"drawstring bag","price":12}]},{"products":[{"name":"golf ball","price":10},{"name":"planner","price":20},{"name":"erasable pen","price":7},{"name":"glove","price":15},{"name":"visor","price":12}]}]

Query

db.collection.aggregate([{"$project":{products:{"$map":{"input":"$products","as":"product","in":{"$concat":["$$product.name"," - ",{"$toString":"$$product.price"}]}}},products_w_price_gte_10:{"$filter":{"input":"$products","as":"product","cond":{"$gte":["$$product.price",10]}}},products_values:{"$reduce":{"input":"$products.price","initialValue":"","in":{"$concat":["$$value",{"$cond":[{"$eq":["$$value",""]},"",", "]},{"$toString":"$$this"}]}}}}}])

Result