Do not assume not-nullable means required

[mx-moth]

Not-null Boolean columns fail this requirement, for example.
<input type="checkbox" required> will not allow the page to be submitted
until it is checked, despite an unchecked/falsey checkbox being valid
data at the model level.

[mlenzen]

I agree that this isn't clear or obvious. My concern with this is that it breaks backwards compatibility. I know I've used this in the past for checkboxes that have to be checked, e.g. "I accept the terms and conditions". Is there another way to express this?

[mx-moth]

It does break backwards compatibility, but I would argue that it breaks it towards being more correct. Required in wtforms is taken to mean True in the context of a checkbox, while not-nullable still means False is a valid value, so the current behaviour does not match what is expected or desired most of the time when using a boolean model field.

The current behaviour is difficult to work with, as the addition of the required/optional validator is done in a section of code that is very difficult to override and modify the behaviour. If you were interested in keeping backwards compatibility, the _nullable_required() call could also be added to the conv_Boolean() method. Developers after behaviour that makes sense could then override either conv_Boolean() to not add the validator, or override _nullable_required() to check the field type before adding the validator.

[mlenzen]

Yeah, I just had a brain fart. I used the Required validator when I wanted the checkbox to have to be checked. A non-nullable Boolean column should be allowed to be false.

[mx-moth]

Thanks!