> ## Documentation Index
> Fetch the complete documentation index at: https://axiom.co/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# ismap

> This page explains how to use the ismap function in APL.

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.

## 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.

<AccordionGroup>
  <Accordion title="Splunk SPL users">
    In Splunk SPL, you typically work with field types implicitly and rarely check if a field is a dictionary. SPL lacks a direct equivalent to APL’s `ismap`, but you might perform similar validations using `typeof` checks or custom functions in `eval`.

    <CodeGroup>
      ```sql Splunk example theme={null}
      | eval is_map=if(typeof(field) == "object", true, false)
      ```

      ```kusto APL equivalent theme={null}
      ['sample-http-logs']
      | extend is_map = ismap(dynamic_field)
      ```
    </CodeGroup>
  </Accordion>

  <Accordion title="ANSI SQL users">
    ANSI SQL doesn’t natively support map types. If you use a platform that supports JSON or semi-structured data (such as PostgreSQL with `jsonb`, BigQuery with `STRUCT`, or Snowflake), you can simulate map checks using type inspection or schema introspection.

    <CodeGroup>
      ```sql SQL example theme={null}
      SELECT
        CASE
          WHEN json_type(field) = 'object' THEN true
          ELSE false
        END AS is_map
      FROM logs
      ```

      ```kusto APL equivalent theme={null}
      ['sample-http-logs']
      | extend is_map = ismap(dynamic_field)
      ```
    </CodeGroup>
  </Accordion>
</AccordionGroup>

## Usage

### Syntax

```kusto theme={null}
ismap(value)
```

### Parameters

| Name    | Type | Description                         |
| ------- | ---- | ----------------------------------- |
| `value` | any  | The value to check for being a map. |

### Returns

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

## Example

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

**Query**

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

[Run in Playground](https://play.axiom.co/axiom-play-qf1k/query?initForm=%7B%22apl%22%3A%22%5B'sample-http-logs'%5D%20%7C%20extend%20is_structured%20%3D%20ismap\(dynamic\(%7B'a'%3A1%2C%20'b'%3A2%7D\)\)%22%7D)

**Output**

| \_time               | is\_structured |
| -------------------- | -------------- |
| 2025-06-06T08:00:00Z | true           |

## List of related functions

* [isimei](/apl/scalar-functions/type-functions/isimei): Checks whether a value is a valid International Mobile Equipment Identity (IMEI) number.
* [isreal](/apl/scalar-functions/type-functions/ismap): Checks whether a value is a real number.
* [iscc](/apl/scalar-functions/type-functions/iscc): Checks whether a value is a valid credit card (CC) number.
* [isstring](/apl/scalar-functions/type-functions/isstring): Checks whether a value is a string. Use this for scalar string validation.
* [isutf8](/apl/scalar-functions/type-functions/isutf8): Checks whether a value is a valid UTF-8 encoded sequence.