WTForms Version 3.1.0 introduced a breaking change for Flask-Admin forms

[chrisdellisantirn]

It seems that WTForms now returns four elements in iter_choices() tuples instead of the two or three that Flask-Admin expects. As a result, whenever I try to render a form that uses a SelectField or a similar field that relies on iter_choices(), I get:

ValueError: not enough values to unpack (expected 4, got 3)

Downgrading WTForms to 3.0.0 resolved the issue. I checked out their change logs and they show:

⚠️breaking change⚠️: iter_choices now returns a tuple of 4 items

Environment:

• Python version: 3.10
• Flask version: 3.1.0
• Flask-Admin version: 1.6.1

[samuelhwilliams]

This is fixed in the (currently alpha) versions of Flask v2.0.0a0 onwards. We're loosely planning to do a full v2 release once mongoengine support (#2541) and azure-blob-storage (#2566) updates have been merged.

You may wish to try those alpha releases for now, based on your use-case, though. I will close this as the only thing outstanding is an official v2 release - there are no further specific code changes needed for this.