How to pass object id in a property?

spaluc

Hi,

I would like to make new QML component, let say a Button that push on the PageStack a page, I want the Page to be specified in Button property:
@
Button {
property string target
id: button1
x: 104
y: 230
text: "Button"
onClicked: {
pageStack.push(target)
}

@
The property target is supposed to be set to a target Page id in Qt Creator. The intent is to type in everything in Design mode without need to fill in onClicked. How to use id stored in a property?

thanks

sierdzio

Ids don't work as properties, they are not visible in C++. You can make the property into a var (or variant), and assign the object to it by [removed]
@
property var target: someObjectId
@

If you need access in C++, you will have to add objectName string and use QObject::findChild().

spaluc

I do not want to access it in C++, I want to access it in QML through property, I want the property to be set in Design mode and pass to push (see line 9) function so that my button is fully configurable in design mode.

sierdzio

Well, does the var property not work?

spaluc

variant property is not visible in Design mode, Qt Creator does not display properties of variant type in Property Editor.

chriadam

The id attribute is a very special attribute. It is not a property, and certain special restrictions apply to it. See the "id attribute documentation":http://doc-snapshot.qt-project.org/5.0/qtqml-syntax-objectattributes.html#the-id-attribute for more information on the topic.

Basically, whenever you use an id in a JavaScript expression in QML, it resolves to a QObject*.

So, you can create a property which can store what the id resolves to, but you cannot store the id itself.

Example:
@
Item {
id: root
property Item childItem: child

Item {
    id: child
}

}
@

Similarly, you can call functions which have a QObject* argument, and "pass" an id as the parameter (since internally, the id gets resolved to a QObject*).

I hope this answers your question, since I'm not entirely certain what you're hoping to achieve.

Cheers,
Chris.

/edit:
You can use "QtObject" as the most basic QObject* property type instead of Item, also, if the object isn't a QDeclarativeItem or QQuickItem derived type.