How to pass values from ScriptDb to Google Sites gadget - google-apps-script

Question

I have a Google Sites page with an embedded Apps Script gadget. On the page, I want to display ScriptDb data upon clicking a button.
My question is: how can I pass ScriptDb results to the JavaScript embedded in my gadget?
Here is my source:
[Sample-Code.gs]
function doGet() {
// return template page
return HtmlService
.createTemplateFromFile('Sample-HTML')
.evaluate().setSandboxMode(HtmlService.SandboxMode.NATIVE);
}
function include(filename) {
return HtmlService.createHtmlOutputFromFile(filename)
.getContent();
}
// assume db contains 10 'records'
function getData(query) {
var db = ScriptDb.getMyDb();
var data = db.query(query);
Logger.log(data.getSize()); // returns '10.0'
return data; // makes showData think this is null
}
[Sample-HTML.html]
<?!= include('Sample-JavaScript'); ?>
<input type="button" value="show data"
onclick="google.script.run
.withSuccessHandler(showData)
.getData({})" />
[Sample-JavaScript.html]
<script>
function showData(db_query_result) {
alert(db_query_result); // returns null.
}
</script>

Answer 1

The value returned by db.query() is an object as defined in the documentation that can not be used directly in your UI, you should return the value in a format that can be shown in the page : a string or an array of strings.
I didn't test but this should work :
function getData(query) {
var db = ScriptDb.getMyDb();
var result = db.query(query);
Logger.log(result.getSize()); // returns '10.0'
var results = db.query({type: 'person'});
var data = [];
while (results.hasNext()) {
data.push(results.next());
}
return data; // data is an array of results
}