What is the best way to declare a global variable in QML?

NTMS

Hi,

I have a 2 (*.qml) as shown below. In my QML Application, I'd like to execute a Javascript-code before loading it. Then I need a global variable like "var result" so I can access in other qml page (Currency.qml). Component.onCompleted is not what I am looking for. I need something before loading the Main.qml.

How do I do that? Thanks.

// Startup qml
Main.qml
{
         // js function load json data
          ....
          ....
         var result = JSON.parse(request.responseText)

     // Load Currency qml
      Currency.qml {

      }
}


Currency.qml
{
        // assign a value to stg textbox in Currency.qml
         eStgSell.text = result.stg.sell
}

raven-worx

@NTMS
Either a QML singleton object/component holding the variable.

Or even easier use a context property (C++).

NTMS

@raven-worx I am getting error when I use singleton

I created a GlobalStyleMain.qml as shown below.

pragma Singleton
import VPlayApps 1.0
import QtQuick 2.0

QtObject {
    property var currencyGetJsonData: ({})
    property var weatherGetJsonData: ({})
}

In Main.qml I call getCurrencyJsonData as shown below

import "."

....
....
....

   function getCurrencyJsonData() {
       var request = new XMLHttpRequest()
       request.open('GET', 'https://****************', true);
       request.onreadystatechange = function() {
           if (request.readyState === XMLHttpRequest.DONE) {
               if (request.status && request.status === 200) {
                   
                  // Json data assign to global varible in here
                   GlobalStyleMain.currencyGetJsonData  = JSON.parse(request.responseText)
                   console.log("Success")
               }
               else {
                   console.log("LogError:", request.status, request.statusText)
               }
           }
       }
       request.send()
       console.log("Json Finished")
   }

In Currency.qml I assign the values as shown below (with error)

import "."

....
....
....

// I get error in below as:
// TypeError: Cannot read property 'stg' of undefined
 eStgSell.text = GlobalStyleMain.currencyGetJsonData.stg.sell

raven-worx

@NTMS
did you create a qmldir file as described in the docs?

NTMS

@raven-worx
I try to implement http://doc.qt.io/qt-5/qtqml-cppintegration-topic.html
and there isn't any qmldir files?

I red too many articles about qml and C++. Any every time I get more confused.
Sorry for asking but am new to qml :( do you know any easy way out?

raven-worx

@NTMS
you should follow the link i had posted...

NTMS

@raven-worx I will try, thanks