Pass index to custom callback in controllers binding

[oskarwrobel]

Right now is:

        controllers.bind( data ).as( ( item, locale ) => {
            if ( !item.foo ) {
                return null;
            } else if ( item.foo == 'bar' ) {
                return new BarController( ..., BarView( locale ) );
            } else {
                return new DifferentController( ..., DifferentView( locale ) );
            }
        } );

and I'm thinking about something like this:

        controllers.bind( data ).as( ( item, locale, index ) => {
            if ( item.inactive ) {
                return null; // Does not increment index.
            } else if ( index < 10 ) {
                return new Controller( ..., FullView( locale );
            } else {
                return new Controller( ..., CompactView( locale );
            }
        } );

Question is what will happen when new item will be added at the top of already rendered collection?

[oleq]

To work like this, the entire ViewCollection would need to be re–rendered because current implementation assumes that once added, the View is immutable – it does not change it's class as long as it belongs to the VC.

It is possible to implement it, but the question is do we really need it? Could an additional controllers.on( 'add', ... ) listener handle a necessary transformation?

[oleq]

This issue is still valid but for ViewCollection because Controller class is gone now (#95).

[oleq]

@oskarwrobel Does https://github.com/ckeditor/ckeditor5-utils/issues/215 fix this issue?

[oskarwrobel]

Nope. But I'm not sure if this is something that we need anymore. CollaborativeComments uses something similar because collapsed comment displays only the first and the last comment but there is an additional view between those comments:

Models:                Views:
[ Comment 1 ]
[ Comment 2 ]          [ Comment 1 ]
[ Comment 3 ]  ----->  [ Additional view counter ]
[ Comment 4 ]          [ Comment 5 ]
[ Comment 5 ]

And this is handled by an additional collection that is between collection of all models and view collection:

All models:            Filtered models:       Views:
[ Comment 1 ]
[ Comment 2 ]          [ Comment 1 ]          [ Comment 1 ]
[ Comment 3 ]  ----->  [ Counter   ]  ----->  [ Counter ]
[ Comment 4 ]          [ Comment 5 ]          [ Comment 5 ]
[ Comment 5 ]

[Reinmar]

I assume this is not relevant anymore.