Re: [Interest] DelegateModel: Dynamic Delegate Model groups

[Jason H]

I have confirmed with Qt Support that there is an issue with QQmlListProperty. The suggested work-around is to use QFilterSortProxyModel. I've done models in the past (~10y.a.). What do I need to know about translating this to be used in QML with DelegateModelGroup? I found some articles at ImaginativeThinking.ca, but they didn't get into how to use a QFilterSortProxyModel with DelegateModelGroups. 

 

Can anyone tell me what I need to know (or point me to a resource) about specifically using QFilterSortProxyModel with DelegateModelGroups? 

Sent: Wednesday, July 27, 2016 at 12:02 PM
From: "Jason H" <jh...@gmx.com>
To: "Jérôme Godbout" <jer...@bodycad.com>
Cc: "Interests Qt" <interest@qt-project.org>
Subject: Re: [Interest] DelegateModel: Dynamic Delegate Model groups

Thanks Jerome! I'm making progress, but not quite there.

 

I've got it creating the list with the correct types now, but when I set the groups property of DelegateModel, it complains.

DelegateModel {

groups: instantiator.delegateModelGroups // property list<DelegateModelGroup> delegateModelGroups // Error: Unable to assign QQmlListReference to QQmlListProperty<QQmlDelegateModelGroup>

}

 

Also, I do not know what happens with the peristedItems and items groups of Delegate model when I assign it this way.

 

Sent: Wednesday, July 27, 2016 at 9:34 AM
From: "Jérôme Godbout" <jer...@bodycad.com>
To: "Jason H" <jh...@gmx.com>
Cc: "André Somers" <an...@familiesomers.nl>, "Interests Qt" <interest@qt-project.org>
Subject: Re: [Interest] DelegateModel: Dynamic Delegate Model groups

The way you create the object seem to be all fine. It's the container of multiple obj that may have a problem with it.

 

When you specify a QQmlListProperty<A> you cannot assign anything else then A object into it and sometime it may get annoying when you have a list<B> cannot assign since they are not of the specified A type (even if A is B, the invert would cause you no trouble).

 

in your case A is DelegateModelGroup

B is QObject*

 

I'm guessing you are doing a loop on Compoenent create (coudl use an instanciator) of the component and try to assign the generated list (which are QQmlListProperty<QtObject> into QQmlListProperty<DelegateModelGroup> list, am I right?

 

DelegateModelGroup instance can be assign to list<QtObject>, list<DelegateModelGroup> but not to list<Item>!

 

Item { id: component property list<Item> a property list<QtObject> b property list<DelegateModelGroup> c Instantiator { model: 2 onObjectAdded: { console.log('added', object); function append_obj(l) { console.log('before', l); try { var tempo = adaptQQLP(l); tempo.push(object); console.log('list', tempo); return tempo; } catch(e) { console.log('!!!ERROR'); console.log(e); return []; } } component.a = append_obj(component.a); component.b = append_obj(component.b); component.c = append_obj(component.c); console.log('after a', component.a); console.log('after b', component.b); console.log('after c', component.c); } onObjectRemoved: { console.log('removed', object); }

// Switch delegate to see the effect //QtObject {} //Item {} DelegateModelGroup {} } Component.onCompleted: { console.log('End', adaptQQLP(a), adaptQQLP(b), adaptQQLP(c)); } }

 

On Tue, Jul 26, 2016 at 4:07 PM, Jason H <jh...@gmx.com> wrote:

Oh, I may see the problem, I created the objects as:

Component {
	id: recipientComponent
	DelegateModelGroup {}	
}

var recipientGroup = recipientComponent.createObject(recipientComponent, {includeByDefault: false, name: number});

I don't know how I can more strongly type that. I'd expect Qt to internally try to promote it and succeed.


Sent: Tuesday, July 26, 2016 at 1:43 PM



From: "Jérôme Godbout" <jer...@bodycad.com>
To: "Jason H" <jh...@gmx.com>
Cc: "André Somers" <an...@familiesomers.nl>, "Interests Qt" <interest@qt-project.org>
Subject: Re: [Interest] DelegateModel: Dynamic Delegate Model groups







Just to make sure the concat really generate the JS array, try the following (It should not give any difference, but just to make sure):

 

function adaptQList(src)

{

var rv = [];

for(var i = 0; i < src.length; ++i)

rv.push(src[i]);

return rv;

}

 

But I suspect you have a type mismatch here, since you have a QList<QObject*> and a QQmlLisProperty<QQmlDelegateModelGroup>, try with a property of type QQmlLisProperty<QObject> and affect the value to see if this work (it should). If this work you will need to convert type of have a setter that take QQmlLisProperty<QObject> and do the C++ type check/conversion to your strongly typed QQmlDelegateModelGroup.

 

Jerome

 


 
On Tue, Jul 26, 2016 at 1:33 PM, Jason H <jh...@gmx.com> wrote:




 

Thanks for the pointer, but when I hacked it in as a p.o.c:


groups = [].concat(recipientModelGroups); //Error: Cannot assign QList<QObject*> to QQmlListProperty<QQmlDelegateModelGroup>

(groups is a DelegateModel.group property, recipentModelGroups is a js array of DelegateModelGroups). I think I'm trying to go the other way? Or the QQmlListProperty<QQmlDelegateModelGroup> is too tightly typed?

 

 



Sent: Tuesday, July 26, 2016 at 11:49 AM
From: "Jérôme Godbout" <jer...@bodycad.com>
To: "Jason H" <jh...@gmx.com>
Cc: "André Somers" <an...@familiesomers.nl>, "Interests Qt" <interest@qt-project.org>
Subject: Re: [Interest] DelegateModel: Dynamic Delegate Model groups




QQmlListProperty<> cannot be assign with another QQmlListProperty<> or a QList<>, but it does support _javascript_ Array. I myself made a simple function to convert:

 

function adaptQQLP(list_obj)

{

   return [].concat(list_obj);

}

It does iterate on it and create a _javascript_ array which is enough

 

MyQmlObj

{

   myQQmlListProperty: adaptQQLP(myOtherId_.itsOwnQQmlListProperty)

}

 

This is a workaround the QQmlListProperty madness. This and the clear and push everything back for any modification where performance goes down the toilette. Tumb rules avoid those QQmlListProperty as much as possible your software performance will thank you.

 

Jerome


 
On Tue, Jul 26, 2016 at 11:23 AM, Jason H <jh...@gmx.com> wrote:

> I'd just write my proxy model in C++ and be done with it.
>
> André
>
>
> Op 26/07/2016 om 15:46 schreef Jason H:
> > I want to have groups corresponding to the equivalent of 'SELECT DISTINCT x' query. Then I want each item assigned to a group of it's value of x. For example:
> > 'SELECT DISTINCT x' -> ['a', 'b', 'c']
> > 'SELECT x,y' -> [ ['a', '1'], ['a','2'], ['b','3'], ['c', '4'], ['c','11'] ]
> >
> > Then I have 3 groups: a has 2, b has 1, c as 2, then I want to set filerOnGroup to one of the groups. Is there a way to do this?

DelegateModel.groups is a list<DelegateModelGroup>, but there seems to be no way to add a group to it.
The DelegateModel.groups property resolves (in QtCreator) to an instance of a DelegateModelGroup (having .addGroup()) which applies to adding groups to *model items* and not groups it self.

When I console.log groups, I get:  {"0":{"objectName":"","count":8,"name":"items","includeByDefault":true},"1":{"objectName":"","count":0,"name":"persistedItems","includeByDefault":false}}

So I try:
  var recipientGroup = recipientComponent.createObject(recipientComponent, {includeByDefault: false, name: number}) // (works)
  groups[groups.length] = recipientGroup; but it doesn't take.
Of I try to assign them all at once: groups = recipientModelGroups;
I get: Error: Cannot assign QList<QObject*> to QQmlListProperty<QQmlDelegateModelGroup>

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