tostring

You typically use tostring when working with numeric values, booleans, or other types that need to be converted to strings for string manipulation, formatting, or when combining values in string operations.

Usage#

Syntax#

tostring(value)

Parameters#

Name	Type	Description
value	dynamic	The value to convert to string.

Returns#

If the expression value is non-null, the result is a string representation of the expression. If the expression value is null, the result is an empty string.

Conversion behavior#

The tostring function converts values based on their type:

Integer: Formatted as base-10 string.
Float: Formatted using Go’s FormatFloat function with precision -1. For more information, see the Go documentation.
Boolean: Returns "true" or "false". Nil Boolean values return "false".
Duration: Returns duration-formatted strings. For example, "1m20s".
Datetime: Returns RFC3339Nano formatted datetime string.

Use case example#

Convert trace attributes to strings for string-based analysis and reporting.

Query

['otel-demo-traces']
| where isnotempty(['attributes.http.response.status_code'])
| extend status_str = tostring(['attributes.http.response.status_code'])
| extend duration_str = tostring(duration)
| extend trace_summary = strcat('Service: ', ['service.name'], ', Status: ', status_str, ', Duration: ', duration_str)
| project _time, trace_id, ['service.name'], status_str, trace_summary

Run in Playground

Output

_time	trace_id	service.name	status_str	trace_summary
Jun 24, 09:28:10	abc123	frontend	200	Service: frontend, Status: 200, Duration: 150000000

This example converts trace attributes to strings and creates a summary message, enabling formatted trace reporting and analysis.

strcat: Concatenates strings. Use strcat with tostring to combine converted values into formatted strings.
strcat-delim: Concatenates strings with a delimiter. Use strcat-delim with tostring to join converted values with separators.
toint: Converts input to integer. Use toint to convert strings back to integers when needed.

Other query languages#

Splunk SPL users

In Splunk, you use tostring or tostring() function to convert values to strings. In APL, tostring provides similar functionality for converting various types to string format.

Splunk example

... | eval status_str = tostring(status_code)

APL equivalent

... | extend status_str = tostring(status_code)

ANSI SQL users

In standard SQL, you use CAST(... AS VARCHAR) or TO_CHAR functions to convert values to strings. In APL, tostring provides a simpler way to convert various types to string values.

SQL example

SELECT CAST(123 AS VARCHAR) AS status_str FROM logs;