Just released WTForms 3.1.0 break FAB widgets (including just released 4.3.8)
potiuk opened this issue · comments
The WTForms 3.1.0 introduced a change that breaks implementation of Flask App Builder choices fields based on QuerySelectField.
The problem is that the new choices widget returns now possible "render_kwargs" parameter in "iter_choices" :
See the release notes for 3.1.0
The issue in WTForms is: wtforms/wtforms#692
The PR in WTForms is: https://github.com/wtforms/wtforms/pull/739/files
the change is that "choices" widget expects now 4 values to unpack in SelectFieldBase.iter_choices (value, label, selected, render_kw) where previously there were three (value, label, selected). Unfortunately Flask App builder overrides implementation of the iter_choices in QuerySelectField
Flask-AppBuilder/flask_appbuilder/fields.py
Line 131 in 38180b0
iter_choices method still returns 3 values which means that when core WTF iterates over the field to display their value here: https://github.com/wtforms/wtforms/pull/739/files#diff-70bc7290d3bd4ce3f5436885709a6b8af1086763e4699598e578ee809027eadbR365 it fails with
> for val, label, selected, render_kw in field.iter_choices():
E ValueError: not enough values to unpack (expected 4, got 3)
Environment
Flask-Appbuilder version: Tested with 4.3.6, 4.3.7, 4.3.8 (but previous versions are also affected)
WTForms 3.1.0
pip freeze output:
pip freeze | grep -E "(Flask-App|WTForms)"
Flask-AppBuilder==4.3.8
WTForms==3.1.0
Describe the expected results
When instantiating any choice widgets in WTForms 3.1.0 and installing QuerySelectMultipleField
> for val, label, selected, render_kw in field.iter_choices():
E ValueError: not enough values to unpack (expected 4, got 3)
What should happen - it should not raise the exception.
I am not sure how to easily - minimally - reproduce it but the root cause of the problem is quite clear - It has been detected by the canary build in Apache Airflow (when WTForms got automatically upgraded to 3.1.0 which is compatible with FAB). FAB has WTForms<4, so anyone installing new FAB with latest compatible WTFOrms will have this problem.
You can see example failure here: https://github.com/apache/airflow/actions/runs/6516454013/job/17700187383#step:6:12162
However simply using and displaying QuerySelectMultipleField should trigger it.