delete rows from a <grid> within a class

[pep]

working with a code like this one to fill a grid, I have can't empty the grid:


<grid>
<method event="oninit">
var tmpgroup = new LzDataset(null,{name: 'tempgroup'});
var tmp=tmpgroup.getPointer();
tmp.addNode('toto',{id: 'My groups'});
Debug.write(tmpgroup.serialize());
this.setDatapath('tempgroup:/');
</method>
<gridcolumn> ...



I tried to create a new dataset named temgroup like this:


<method name="clear">
var tmpgroup = new LzDataset(null,{name: 'tempgroup'});
var tmp=tmpgroup.getPointer();
tmp.addNode('toto',{id: 'My groups'});
Debug.write(tmpgroup.serialize());
this.setDatapath('tempgroup:/');
</method>



(it is the same code than above but it does not work)

I also tried to empty the dataset child by child with deleteNode

this.ptr=this.datapath.dupePointer();
if(ptr.selectChild()){
while(ptr!=null){ptr.deleteNode()
}


do not work also, does any one knows how this schould be done?

[pep]

ok it works , i just set tmp to the first node of the dataset and delete the node