how to get value of Hidden object - google-apps-script

Question

I need global variable in google script, to hold page ID, like a string. Here, they suggested to use object Hidden for this purpose. I can create this object and set its value.
Code to achieve the same :
function doGet(e) {
var app = UiApp.createApplication();
//Get current indentificator
var mid = 'page-id';
app.add( app.createHidden('mid').setValue(mid).setId('mid'));
return app;
}
But how can I get this value from another function?
For example :
function maketbl(){
var app = UiApp.getActiveApplication();
app.(?!)
}
Thanks!

Answer 1

I see that your requirement is to have functionality similar to that of global variables. I suggest that you use script properties, user properties or the cache service to accomplish this feat. An example is below
ScriptProperties.setProperty('special', 'sauce'); // Use this to set the property
var specialValue = ScriptProperties.getProperty('special'); // use this to access the property

Answer 2

Try the bellow code:
function doGet(e) {
var app = UiApp.createApplication();
var mid = 'page-id';
var hidden = app.createHidden('mid').setValue(mid).setId('mid');
app.add(hidden);
//Create your handler
var handler = app.createServerHandler('maketbl');
handler.addCallbackElement(hidden)
//Create a button to trigger your function
app.add(app.createButton().setText("go forest").addClickHandler(handler));
return app;
}
function maketbl(e){
var app = UiApp.getActiveApplication();
//Retrieve the hidden field
var hidden = app.getElementById("mid");
//Show the value stored at e.parameter.mid where mid is the name of the field
var dialogBox = app.createDialogBox().setText(e.parameter.mid);
dialogBox.setPopupPosition(100, 100);
dialogBox.show();
return app;
}
Live version here.