Use the toarray function in APL to convert a dynamic-typed input—such as a bag, property bag, or JSON array—into a regular array. This is helpful when you want to process the elements individually with array functions like array_length, array_index_of, or mv-expand. You typically use toarray when working with semi-structured data, especially after parsing JSON from log fields or external sources. It lets you access and manipulate nested collections using standard array operations.

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For users of other query languages

If you come from other query languages, this section explains how to adjust your existing queries to achieve the same results in APL.

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Usage

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Syntax

toarray(value)

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Parameters

NameTypeDescription
valuedynamicA JSON array, property bag, or bag value

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Returns

An array containing the elements of the dynamic input. If the input is already an array, the result is identical. If the input is a property bag, it returns an array of values. If the input is not coercible to an array, the result is an empty array.

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Example

You want to convert a string to an array because you want to pass the result to a function that accepts arrays, such as array_concat. Query 
['otel-demo-traces']
| extend service_list = toarray('123')
| extend json_list = parse_json('["frontend", "cartservice", "checkoutservice"]')
| extend combined_list = array_concat(service_list, json_list)
| project _time, combined_list
Run in Playground Output
_timecombined_list
Jun 24, 09:28:10[“123”, “frontend”, “cartservice”, “checkoutservice”]
Jun 24, 09:28:10[“123”, “frontend”, “cartservice”, “checkoutservice”]
Jun 24, 09:28:10[“123”, “frontend”, “cartservice”, “checkoutservice”]
  • array_length: Returns the number of elements in an array. Useful before applying array_extract.
  • array_index_of: Finds the position of an element in an array, which can help set the startIndex for array_extract.
  • pack_array: Use this to combine scalar values into an array. Use pack_array when you don’t need named keys and want positional data instead.
  • bag_keys: Returns the list of keys in a dynamic dictionary. Use this to inspect or filter contents created by pack_dictionary.
  • bag_pack: Expands a dictionary into multiple columns. Use it to revert the packing performed by pack_dictionary.