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

# ETL: JsonStringToMap

> Use the JsonStringToMap expression function in Integrate.io ETL to parse a JSON string into a map field for downstream transformations and field access.

## Description

Converts a string expression that contains a JSON object to a map (key:value pairs). From the map you can extract fields using the notation map#'fieldname'.

## Syntax

`JsonStringToMap(string_expression)`

## Arguments

*string\_expression* - JSON string

## Examples

`JsonStringToMap('{"userID": 1, "userName": {"lastName": "Doe", "firstName" : "John"} }')` returns a map with two key-value pairs:

* userID: 1
* userName: `{"lastName":"Doe","firstName":"John"}`

To extract the lastName, apply the function twice:

JsonStringToMap(JsonStringToMap('`{"userID": 1, "userName": {"lastName": "Doe", "firstName" : "John"} }`')#'userName')#'lastName' returns Doe

## Notes

The function only converts the first level hierarchy to a map. To map lower hierarchies, either use [JsonExtract](/etl/jsonextract/) or extract the nested object string using the map notation (`field#'objectname'`) and apply the function JsonStringToMap to it as well. For more information, read [How do I process JSON data](/etl/how-do-i-process-json-data/).

## Return value datatype

Map

## Impact of null value

If input is null, returns null.