Google Script - Adding dynamic parameters to href from handler - dynamic

Question

I have a Google Script published as a web app which uses UI service to display an interface with several listboxes. I can get at the values selected thru server handlers.
My problem is that I need to add these values to a url in a anchor defined in my doGet routine. (I am calling a JotForm url, and need the dynamic parameters to pre-populate the form)
I can't see how to modify the anchor from the handler function, or any other way to invoke the url I build in code.

Answer 1

When you want to modify any widget in a Ui created with UiApp, each widget must have an ID that you can use to getElementById() and manipulate the way you want just as if you were in the doGet function.
Here is a simple example to illustrate : (online here)
function doGet(){
var app = UiApp.createApplication().setTitle('test');
var serieNames = [' serie A',' serie B',' serie C'];
var panel = app.createVerticalPanel().setStyleAttribute('padding','30px');
var namesHandler = app.createServerHandler('showPilots').addCallbackElement(panel);
for(var n in serieNames){
var serieSelect = app.createRadioButton('pilotSelect',serieNames[n]).setId('s'+n).addClickHandler(namesHandler)
panel.add(serieSelect);
}
app.add(panel);
return app;
}
function showPilots(e){
Logger.log(JSON.stringify(e));// you can see the source parameter in e that returns the widgets ID of the button you clicked to call the handler
var app = UiApp.getActiveApplication();
var serie = e.parameter.source; // get the ID
app.add(app.createLabel('you clicked '+e.parameter.source));// then get this widget by its ID and modify it
app.getElementById(serie).setText('Clicked');// modify it
return app;// update Ui
}
EDIT : here is a version that manipulates anchors, it is perfectly possible to change the url from a handler.
test here
code :
function doGet(){
var app = UiApp.createApplication().setTitle('test');
var links = ['link 1',' link 2',' link 3'];
var linkshref = ['http://www.google.com','http://www.packtpub.com/google-apps-script-for-beginners/book','http://stackoverflow.com/questions/tagged/google-apps-script'];
var panel = app.createVerticalPanel().setStyleAttribute('padding','30px');
var namesHandler = app.createServerHandler('changeUrl').addCallbackElement(panel);
for(var n in links){
var linkWidget = app.createAnchor(links[n], linkshref[n]).setId('s'+n);
panel.add(linkWidget);
}
var btn = app.createButton('change links',namesHandler);
app.add(panel.add(btn));
return app;
}
function changeUrl(e){
Logger.log(JSON.stringify(e));// you can see the source parameter in e that returns the widgets ID of the button you clicked to call the handler
var app = UiApp.getActiveApplication();
var links = ['New link 1','New link 2','new link 3'];
var linkshref = ['http://www.microsoft.com','http://www.w3schools.com/js/','https://sites.google.com/site/appsscriptexperiments/'];
for(var n in links){
app.getElementById('s'+n).setHref(linkshref[n]).setHTML(links[n]);
}
return app;// update Ui
}