Obtain object type string from QML

Ildar

Hello! How I can obtain type of a object from QML code?
I need this feature in Loader:

@Loader {
sourceComponent: myObj.type === "MyObject" ? delegate1 : delegate2
}@

nologinma

The correct form is the following:

@a = (b==0)?1:0;@

but in you example I see 3 '='

In any case you cannot use == for the string.

The correct code is the following (I suppose that myObj.type return a string):

@QString mystring;

mystring(myObj.type);

mystring.compare("MyObject") == 0 ? delegate1 : delegate2;@

in your case will be the following:

@Loader {
sourceComponent: myObj.type.compare("MyObject") == 0 ? delegate1 : delegate2
}
@

Ildar

Thank you for reply!
You may read about tripple equals (===) in docs: "Comparison operators":http://www.c-point.com/javascript_tutorial/jsgrpComparison.htm

Main problem is obtaining type information about a object from QML. I don't know how do it! In documentation about QObject ("QObject":http://qt-project.org/doc/qt-5/QObject.html) exists only one property - objectName, but metaObject() is not available under QML.

I use small hack:
In my objects i add new property:
@Q_PROPERTY(QString className READ className CONSTANT)

QString className()
{
return metaObject()->className();
}
@

And in QML:
@ListView {
model: myModel
delegate: Component {
property bool isObject1: className === "MyObject1"

            Text {
                text: isObject1 ? property1 : property2
            }
    }
}@

This is ugly, but it is works.

Ildar

bq. In any case you cannot use == for the string.

Why ?

nologinma

bq. You may read about tripple equals (===) in docs: Comparison operators [c-point.com]

you are right! I never stop learning.

I developed the following example:

@import QtQuick 2.2
import QtQuick.Controls 1.1

ApplicationWindow {
visible: true
width: 2560
height: 1600
color: "white"

Rectangle {
    width: 200
    height: 100
    color: "red"

    Text {
        id: mytext
        objectName: "MyTextObject"
        anchors.centerIn: parent
        text: "Hello, World!"
    }

    MouseArea {
        anchors.fill: parent
        onClicked:
            {
             parent.color = "blue"
             mytext.text = mytext.objectName == "MyTextObject" ? "YES" : "NO"
            }
    }
}

}@

I get the name of the object by objectName method:

@mytext.objectName@

in your case you can use:

@Loader {
sourceComponent: myObj.objectName === "MyObject" ? delegate1 : delegate2
}@

but you have to assign to your object objectName = "MyObject"

Ildar

So, this is also possible, but objectName is instance specific, not a type specific. It is more suitable to use objectName for other purposes, IMHO.

nologinma

Please share your code about MyObject1 object just to understand better....

Ildar

I mean that if we using objectName() method that we must set this property to all instances of class in constructor or in other places. For example:
@
MyObject1()
{
// setObjectName("MyObject1");
// or
setObjectName(metaObject()->className());
}
@

or as you wrote:
@
Text {
id: mytext
objectName: "MyTextObject"
anchors.centerIn: parent
text: "Hello, World!"
}
@

But if we using className wrapper property than we may define this methods in our class declaration. And this is allow to us to making safe inheritance from MyObject1: for subclasses className() return actual className!
@Q_PROPERTY(QString className READ className CONSTANT)

QString className()
{
return metaObject()->className();
}@

and we can using objectName for other purposes, for example:
@
MyObject1 objA = new MyObject1();
objA.setObjectName("A");

MyObject1 objB = new MyObject1();
objB.setObjectName("B");
@

This is can be useful for debugging.