Product collection includes price field. Price field can be a single or multivalued.
Output should be maximum price value.
Input:
{
"_id": ObjectId("5b239304c70f3826b2862f83"),
"price": ["09.8", "90.86"]
} {
"_id": ObjectId("5b239304c70f3826b2862f84"),
"price": ["100"]
} {
"_id": ObjectId("5b239304c70f3826b2862f85"),
"price": "95"
}
output:
{ "price": "100" }
You should convert your price field to a numerical type but the below works with strings, too:
db.collection.aggregate([{
$group: {
_id: null, // group all documents into the same bucket
price: { // create a new field "price"
$max: { // which will be the maximum of
$cond: [
{ $eq: [ { $type: "$price" }, "array" ] }, // if the "price" field is an array
{ $reduce: { input: "$price", initialValue: 0, in: { $max: [ "$$this", "$$value" ] } } }, // the maximum value inside the value
"$price" // otherwise just the value of the "price" field
]
}
}
}
}], { collation: { locale: "en_US", "numericOrdering": true } })
See this thread for how to convert your data: how to convert string to numerical values in mongodb
