[Development] [QML] ListModel discards item's method

[Ben Lau]

On 4 May 2014 03:30, Nurmi J-P <jpnurmi at digia.com> wrote:

> On 03 May 2014, at 16:04, Ben Lau <xbenlau at gmail.com> wrote:
>
> > Hi,
> >
> > I have few questions about the implementation of ListModel and the
> design principle about using models with object in QML application.
> >
> > I would like to use a model class to hold a list of item (or  C++
> QObject ) with custom methods / slot functions. However, I found that after
> the item/QObject is appended to the ListModel, then access the model to get
> back the object. The associated method will become a property value and not
> able to call.
> >
> > The following code demonstrates the problem:
> >
> > import QtQuick 2.0
> > import QtTest 1.0
> >
> > TestCase {
> >
> >     Item {
> >         id : testItem
> >         property string name : "testObject"
> >         function testMethod() {
> >             return -1;
> >         }
> >     }
> >
> >     ListModel {
> >         id : listModel
> >     }
> >
> >     function test_ListModel() {
> >         listModel.append(testItem);
> >         compare(listModel.count , 1);
> >
> >         var item = listModel.get(0);
> >
> >         compare(item !== testItem, true); // They are not the same object
> >         compare(item.name , "testObject");
> >
> >         expectFail("","The testMehod() should be a function but now it
> becomes a property");
> >         compare(typeof item.testMethod , "function");
> >     }
> >
> > }
>
> Hi,
>
> Notice that ListModel::append() takes a JS dictionary, and get() returns
> it. Make it something like:
>
>    listModel.append({"item": testItem});
>    var obj = listModel.get(0);
>    compare(obj.item, testItem);
>
> --
> J-P Nurmi
>
>

Thank for your reply. The solution works! And that inspired me for another
alternative solution:

import QtQuick 2.0

import QtTest 1.0


TestCase {


    Item {

        id : testItem

        property string name : "testObject"

        property var object : this

        function testMethod() {

            return -1;

        }

    }


    ListModel {

        id : listModel

    }


    function test_ListModel() {

        listModel.append(testItem);

        compare(listModel.count , 1);


        var item = listModel.get(0);

        compare(typeof item.object.testMethod , "function");

        compare(item.object.testMethod() , -1);


    }


}






> _______________________________________________
> Development mailing list
> Development at qt-project.org
> http://lists.qt-project.org/mailman/listinfo/development
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.qt-project.org/pipermail/development/attachments/20140504/2ccc589c/attachment.html>