WireHttp::setData() method   
Set an array of data, or string of raw data to send with next GET/POST/etc. request (overwriting the existing data or rawData)
Usage
$http->setData($data);Arguments
| Name | Type(s) | Description | 
|---|---|---|
| $data | arraystring | Associative array of data or string of raw data | 
Return value
$thisObject instance it was called from (method supports fluent interface).
API reference based on ProcessWire core version 3.0.252