> ## Documentation Index
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# ETL: QueryStringToMap

> Parse a URL query string (key1=value1&key2=value2) into a key-value map structure. Use for processing web URL parameters in ETL data pipelines.

## Description

Converts a string field that contains a URL query string (...?key1=value1\&key2=value2) to a map of key:value pairs. From the map you can extract fields using the map notation:\
`map#'fieldname'`

## Syntax

`QueryStringToMap(string_expression)`

## Examples

`QueryStringToMap('http://someurl/?origin=135&origin=246&id=321')` returns  \[origin#'135,246',id#'321'] which is a map with two keys: origin and id. Note that the value for origin contains both values from the original query string separated by comma.

## Notes

If the input string contains a question mark (?) then the part that follows will be processed ("&" is used to split pairs and "=" is used to split keys and values). If the input string does not contain a question mark, the entire string will be processed in the same manner.

## Return value datatype

Map of string values

## Impact of null value

If input is null, returns an empty map.