[{values:[{item:"widget",price:1,color:"red"},{item:"foobar",price:2,color:"blue"}]}]

db.collection.aggregate([{$addFields:{map:{$map:{input:"$values",as:"values",in:{/**----vvv mistake*/item:"$values.item",price:"$values.price"}}}}}])/** db.collection.aggregate([* {* $addFields: {* map: {* $map: {* input: "$values",* as: "values",* in: {* //----vvvv fixed mistake, check the outcome* item: "$$values.item",* price: "$$values.price"* }* }* }* }* }* ])*/