How to set RelayState for IDP initiated SSO

[scholtron]

Based on the example code here, how would one set the relayState for IDP initiated SSO?
https://github.com/lightSAML/lightSAML-IDP/blob/master/web/idp/initiate.php

It seems this was worked on in the past, but it was not clear how to set it.
lightSAML/lightSAML#51

$action = $sendBuilder->buildAction();

//$context->setRelayState($relayState);
$action->execute($context);
//$context->setRelayState($relayState);

$context->getHttpResponseContext()->getResponse()->send();```

[scholtron]

My not so great workaround was to modify the SAML html before sending in, in case the RelayState is needed:
$response = $context->getHttpResponseContext()->getResponse(); $response = str_replace('<input type="submit" style="display:none;" />', '<input type="submit" style="display:none;" /><input type="hidden" name="RelayState" value="'.$RelayState.'" />', $response); $response = implode("\n", array_slice(explode("\n", $response), 4)); echo $response; exit;