Exception: Cannot use the "tables" module in the designer

[chad63e]

Any chance this exception can be resolved? I understand we don’t want server calls being made in the designer, but if you want to use a class to perform a condition check, this is very obnoxious.

For example, in one of my classes, I want to do an isinstance check to confirm that the data coming in is a Row instance. However, this little exception lights my custom form up in red.

Exception: Cannot use the "tables" module in the designer

[p.colbert]

It’s not documented, but see here:

Question about Custom Components in Beta Designer

Ah, that would do it! There’s a limited set of modules available inside the designer, but we’ll add anvil.tz to it However, here’s an as-yet-undocumented but useful feature: You can write: from anvil.designer import in_designer and now you have a boolean variable called in_designer, which you can use! So for example, you could replace your import anvil.tz with: from anvil.designer import in_designer if not in_designer: import anvil.tz Then you won’t get the ImportError in the d…

for a way to avoid executing that code in the designer.

[chad63e]

For some reason, I thought that this little import had been removed, but to my delight it is still available.

from anvil.designer import in_designer

This solves the problem!