ismap

Use the ismap function in APL to check whether a value is of the dynamic type and represents a mapping (also known as a dictionary, associative array, property bag, or object). A mapping consists of key-value pairs where keys are strings and values can be of any type. This function is especially useful when working with semi-structured data, such as logs or telemetry traces, where fields might dynamically contain arrays, objects, or scalar values.

Use ismap to:

• Filter records where a field is a map.
• Validate input types in heterogeneous data.
• Avoid runtime errors in downstream operations expecting map values.

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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

ismap(value)

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Parameters

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Returns

Returns true if the value is a mapping (dictionary), otherwise returns false.

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Example

Use ismap to find log entries where a dynamic field contains structured key-value pairs, such as metadata attached to HTTP requests.

Query

['sample-http-logs']
| extend is_structured = ismap(dynamic({"a":1, "b":2}))

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Output

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List of related functions

• isreal: Checks whether a value is a real number.
• isstring: Checks whether a value is a string. Use this for scalar string validation.