Strip attributes via before_save, not just before_validation

[knagode]

It is often very handy to use .save(validate: false), for example when allowing users to save drafts.

I noticed (too late) that strip_attributes only strips attributes before validation. My expectation was that it would always convert '' to NULL. Because it didn’t, I ended up with many empty string values in the database, which caused unique index exceptions ('' behaves very differently from NULL when dealing with unique indexes, and I wanted to ensure that empty strings are never persisted).

I believe strip_attributes should also work when using .save(validate: false), or at least provide a configurable setting to enable this behaviour by default across all models.

Workaround: call .valid? before .save(validate: false). This works, but it doesn’t feel intuitive.

[rmm5t]

I think I'd like to consider moving strip_attributes to use the normalizes API, which would also solve for this. See #67.

However, this will likely require Rails 8.1 (rails/rails#53887)

In the meantime, redefining strip_attributes for your app and/or performing the before_save manually like you did is a fine workaround.

If I incorporated this before_save behavior into strip_attributes to support versions prior to Rails 8.1, I'd want to make sure that the stripping normalization only occurred once per #save.

[knagode]

I added code to ensure that stripping normalization isn’t executed twice. I didn’t add a test, as I don’t think it’s necessary, but I’m happy to add one if you think it’s worth it before merging. I can confirm that this PR would prevent several issues on our side but I understand that not many people use .save(validate: false).

If we were already on Rails 8.1, I’d probably just replace the strip_attributes operation with Rails’ built-in normalize.