I´m guessing you are displaying the form in a webviewer and want to extract the lookup-data into fields in FileMaker?
First of all you can´t use the GetLayoutObjectAttribute function to do this since it will only fetch the source of the webpage. It will not fetch the data currently being displayed only the HTML that was initially loaded from the http-request.
You can however add a JavaScript callback that fires when the user selects a value from the dropdown. The callback use window.location to call a FileMaker script using FileMaker URI schema and sends the data from the inputs to the filemaker-script as parameters. The filemaker script then stores them in the database.
Something like this
<script type="text/javascript">
function storeData() {
// Set up base URI. You need to modify host-ip, database name and script name
var uri = 'FMP://your-host-ip/databasename?script=scriptname';
// Add form fields as parameters to the URI. These will be $variables in your filemaker script
uri = uri + getParameter('street_number');
uri = uri + getParameter('route');
uri = uri + getParameter('locality');
uri = uri + getParameter('administrative_area_level_1');
uri = uri + getParameter('postal_code');
uri = uri + getParameter('country');
// Call the URI to perform FileMaker script
window.location = uri;
}
function getParameter(name)
{
// Return a string that can be used as a URI param
return '&$' + name + '=' + document.getElementById(name).value;
}
</script>
You need to trigger the storeData() function using a google-api callback or some other other mechanism like a button with onClick.
You also need to add a script in FileMaker that can be called by the URI. Whatever you name that script you also need to insert into the scriptname-part of the URI. You also need to change the URI to your hosts IP or domain and the databasename where the filemaker-script is created.
In your FileMaker script the values will be availible as $variables and you can set them to fields using Set Field script step.
Hope this helps