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$objectToArray

Converts an object to an array of key-value pairs, where each element is a document with 'k' (key) and 'v' (value) fields.

Syntax

{ $objectToArray: <object_expression> }

Parameters

object_expressionobjectrequired

Expression that resolves to an object to be converted to array format

Examples

Convert object to array

Transform object fields into key-value pair array

Query:

db.products.aggregate([{ $project: { items: { $objectToArray: "$inventory" } } }])

Output:

Document with items array containing k/v pairs from inventory object

Process object fields dynamically

Convert object to array for dynamic field processing

Query:

db.products.aggregate([{ $project: { pairs: { $objectToArray: "$attributes" } } }, { $unwind: "$pairs" }, { $match: { "pairs.v": { $gt: 100 } } }])

Output:

Documents with attribute pairs where values are greater than 100

Transform nested object

Convert nested object structure to array format

Query:

db.sales.aggregate([{ $project: { monthlyData: { $objectToArray: "$salesByMonth" } } }])

Output:

Document with monthlyData array containing monthly sales key-value pairs

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