In an effort to minimize bloat, I'm going to try to just describe the problem and the suspected culprits: From a Message Handler on a Tree component, I am receiving a TypeError due to a function in my script returning None. I am feeding the Tree's items property to the function as x: x = self.prop…

BQuacken, you gotta embrace duck typing :smiley: [image] Function to convert json string or python dict into ObjectWrapper Ignition Forcing each to the expected type while traversing makes a deep copy: def sanitize_tree(element): if hasattr(element, '__iter__'): …

That makes a lot of sense! (And I'm embarrassed that I had no idea what that was, in spite of my name :sweat_smile:) Unfortunately - even though utilizing Justin's function you linked to is certainly better than just converting the top level list - the result is the same; I receive a TypeError due …

Don't check the type. Neither with type() nor with isinstance(). Duck typing means to use the methods you expect for a list (iteration, whatever), and it'll walk like a duck (list) if it is duck-like (list-like).

Hmm... Perhaps then it is time to expand on what I'm doing a little bit. The full find_first() function looks like this: def find_first(obj_to_inspect, val_to_find, listpath=()): if isinstance(obj_to_inspect, dict): for key, value in obj_to_inspect.items(): item = find_first(value, v…

Obviusly, you should probably insure that you don't send a 'NoneType' object to the function, but if for some reason you can't do that, then just add a check: def find_first(obj_to_inspect, val_to_find, listpath=()): if obj_to_inspect and not isinstance(obj_to_inspect,str): if hasAttr(o…

Oh! .... :man_facepalming: Yeah, that's probably it. Let me try that.

I check (with hasattr()) for the items method for duck-typed dictionaries. (Or just try to iterate over items() and catch the exception.) Then check for __iter__ or just attempt to iterate. If both of those fail, I would then do the string search.

The key insight is that strict subtyping is just too narrow for Ignition's Jython environment. Jython models Java and Python as (basically) two completely distinct type hierarchies. Any Java code you interact with (literally everything written by IA) can return either a "true" Python object or a Ja…

Perspective Scripting: Data Type Issue

Ignition

paul-griffith July 23, 2025, 4:28pm 2

BQuacken, you gotta embrace duck typing