Unload Dialog component through Loader

[MaxKazakov]

Hello.
I use Loader to load my component based on Dialog object.

Loader {
        id: dialogLoader
        anchors.centerIn: parent

         onLoaded: {
             item.modality = Qt.WindowModal
             item.visible = true
         }
    }

I load component using "source" property (set qml file) like:

 function showModalWindow(qmlFile) {
        dialogLoader.source = qmlFile;
        if (dialogLoader.item == null) {
            console.log("Error creating object");
        }
    }

When dialog window closed I would like unload my component. So, I need to set into Loader source property an empty string.
I decided if dialog window visible property go to false I should unload it. I implemented the Connections object and connected to onVisibleChanged signal handler:

 Connections {
        target: dialogLoader.item
         onVisibleChanged: {
            if (!dialogLoader.item.visible){
               dialogLoader.source = "";
            }
        }
    }

But when I do some action that hide my dialog window (press OK, Cancel or cross button) this handler does not work.

What is the best way to implement logic I want?
Thanks!