# PDL_GetParamJson

## Description

Used during a service callback. The callback function is passed a `parms` parameter. This API takes that parameter and returns a JSON-formatted string. This is for callbacks that are expecting something more involved than `int`, `double`, `boolean`, or `string` values.

The returned pointer is only valid during the callback function. It points to internal memory; do not attempt to free or modify it.

See Accessing Services for more information on service callbacks.

## Syntax

>     const char *PDL_GetParamJson(PDL_ServiceParameters *parms);

See also:

- PDL_GetParamDouble
- PDL_GetParamInt
- PDL_GetParamString
- PDL_ServiceCall
- PDL_ServiceCallWithCallback
- PDL_UnregisterServiceCallback