Custom expressions evaluation

[nimbit-software]

To start thats a lot the the great engine.

We are looking into using for transforming/enhancing iot data. That means we use it to combine fields and create new ones (which works).

We have the problem that not all the fields come in at the same time, while i understand that the evaluation is stateless id like to have to possibly to evaluate to null/nil/undefined in case the field is not available. Because some of the fields could be there and they should be evaluated.

My idea was to create a custom node and the call the evaluate function to run the test evaluation myself and handle the errors one by one. Is that possible? And could i reuse the JDM expression panel?

One thing that might also be nice is to register custom functions that can be used in the expression nodes. If there is any interest on expanding that id be glad to help make it happen.