Re: CellTree question about varying cell composition

Is there a way to persuade people to answer questions here? Or even
to suggest possibilities? Searching allows me to find lots of
questions like this about CellTree, but I can't find any answers.
Help? Someone?

Thank you.

On Apr 2, 11:52 pm, tomInNewEngland <tsgou...@gmail.com> wrote:
> Hi All:
>
> I have a CellTree and I want to use two different cells for the leaf
> and branch nodes.  The leaf nodes are all to have a checkbox and the
> brances are not.  Leaves and branches appear on the same levels.
>
> I constructed a CompositeCell out of a CheckboxCell and a homegrown
> cell (based on AbstractCell<T>), and I put a test in the
> CompositeCell.render() method, that looked something like this:
>
> if (cell instanceof CheckboxCell) {
>   if (value.isLeaf()) {
>     cell.render(context, hasCell.getValue(value), sb);
>   }
>
> }
>
> With this code, the checkbox cell wasn't rendered at all for the
> branch nodes.  This appeared to work at first, but selecting a branch
> node would give me an error that seemed to be at the Javascript
> level.  It read: "(Typeerror) elem is null".  None of my code was
> identified in the stack trace, so I don't get what was wrong.
>
> Can someone suggest what that error might have meant, or better,
> suggest the right way to go about designing a cell that's different
> for leaf and branch nodes that might be siblings in the CellTree.
>
> Another question: when designing a cell to use, what is the right way
> to test the values that will be displayed in that cell?  Besides
> including the checkbox or not, I'd like to vary the look based on
> other parameters.
>
> Many thanks,
>
>  -Tom

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