ExtPersist beforeRestore event

[HobieCat]

Hello there,
I've added a beforeRestore event being fired before the tree status is restored by ExtPersist.
The callback function is passed just like with the restore event, and it may return false to prevent tree state restoration.
If you find this useful, please accept the pull request and merge the code at your convenience.

This should not break any demos, you decide if a new demo is needed.
I suggest to update the wiki and the documentation, feel free to ask if I could be of any help.

Cheers!

[mar10]

Thanks, that may be useful. Is there a concrete use-case? Should we add a way to control what kind of status (select, expand, active) is / is not restored?

[HobieCat]

Let me try to explain the use-case that made me add this event.
Let's pretend I have a fancytree.php outputting the javascript that loads and displays the fancytree.
If I pass it a get parameter (fancytree.php?forceKey=123) where the value it's a node.key that node must be selected, expanded and activated.
The fancytree.php injects the get parameter in a javascript variable, let's call it forceKey and let its value be 0 if no $_GET['forceKey'] has been passed. Under this assumptions, I initialize the fancytree like:

var forceKey = <?php echo isset($_GET['forceKey']) ? intval($_GET['forceKey']) : 0 ; ?>
$('#tree').fancytree({
    ...
    init: function() {
        if ( forceKey>0 ) {
            // do a getNodeByKey and select, expand and activate the found node
        }
    },
    beforeRestore: function() {
        return forceKey==0; // ExtPersist will not restore, init will take care of selecting, expanding and activating
    }
    ...
});

This use case I very simple and does not take care of node status, it can be quite easily extended to have beforeRestore return an object/array with select, expand and active booleans as a rough idea.
Please let me know if i can be of any help on writing this piece of code and excuse me for my bad english and if I didn't make myself clear: it's almost 01:30 of a quite hot Friday night here in Rome...

Cheers!

[mar10]

Probably the same time zone (I am located near Hamburg) but definitely not the same climate zone (had some snow today...)
I think I am going to merge your PR, after I finished the current refactorings.
Thanks for contributing.

[HobieCat]

Excellent, thanks to you for your great job!